Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: SeanBK on August 26, 2008, 06:47:16 am
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$1400us. New sensor - higher ISOs, Live view..not bad
Love the competion.
http://www.usa.canon.com/consumer/controll...9&modelid=17499 (http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=139&modelid=17499)
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$1400us. New sensor - higher ISOs, Live view..not bad
Love the competion.
http://www.usa.canon.com/consumer/controll...9&modelid=17499 (http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=139&modelid=17499)
[a href=\"index.php?act=findpost&pid=217272\"][{POST_SNAPBACK}][/a]
Interesting your choice of thread title: "Canon 50D @ 15MP". It suggests its the mp that matters above all. I suggest that is not the case. Having said that, are we closing in on the 20mp budget dslr before too long? Where does the high end dslr evolve to after that? Are we stuck with an unwanted megapixel race or is the dslr market sophisticated enough not to go down that path like the compact camera market has?
Quentin
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Are we stuck with an unwanted megapixel race or is the dslr market sophisticated enough not to go down that path like the compact camera market has?
It sure does look that way, doesn't it? The switch in the lower end dSLRs from CompactFlash to SD was/is a clear sign the compact market is saturated to the point the manufacturers are now trying to get them to "step up" to a dSLR.
15MP on an APS-C sensor? Isn't that overkill? Didn't Canon learn their lesson with the 1DSMK3?
My guess is as long as the manufacturers can convince the lemmings they need more megapixels, they'll continue down this silly path, while real improvements will trickle in slowly.
You bring up an interesting question regarding the high end, though.....just where does Canon (and Nikon and the others) go from here? If we're lucky, we'll start to see advances in lens design (at a price, of course) that will (hopefully) be able to resolve all that those sensors are capable of capturing.
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Where does the high end dslr evolve to after that? Are we stuck with an unwanted megapixel race or is the dslr market sophisticated enough not to go down that path like the compact camera market has?
[a href=\"index.php?act=findpost&pid=217275\"][{POST_SNAPBACK}][/a]
For me, it is all about SQRT(MP/1.000.000)*SQ(DR*10). Meaning that MP is exponentially less important than DR.
Unfortunately, I think that most DSLR manufactuers will probably listen to their marketing dpt that will most probably convey the message that the average buyer having only 3 neurones, and needing 2 to use his credit card, can only look at one figure with the remaining neurone, and that figure is going to be MP... Funny that they would expect at the same time these customers to be able to use more and more complex features at every release... go figure.
What is the power of 12 stop DR vs 11 stop DR when you can do 15 MP vs 12 MP at a fraction of the developement cost? You are "3.000.000 something" better vs only "1 something" better.
This being said, the 50D might have excellent DR as well, these comments are not directed specifically at Canon.
Cheers,
Bernard
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For me, it is all about SQRT(MP/1.000.000)*SQ(DR*10). Meaning that MP is exponentially less important than DR.
Unfortunately, I think that most DSLR manufactuers will probably listen to their marketing dpt that will most probably convey the message that the average buyer having only 3 neurones, and needing 2 to use his credit card, can only look at one figure with the remaining neurone, and that figure is going to be MP... Funny that they would expect at the same time these customers to be able to use more and more complex features at every release... go figure.
What is the power of 12 stop DR vs 11 stop DR when you can do 15 MP vs 12 MP at a fraction of the developement cost? You are "3.000.000 something" better vs only "1 something" better.
This being said, the 50D might have excellent DR as well, these comments are not directed specifically at Canon.
Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=217283\"][{POST_SNAPBACK}][/a]
Lets wait to see some testing before we say it has less DR, technology changes, my P21 has no more DR than the P45 which has smaller photosites. Technology changes, by most peoples accounts the 1ds mark 3 has the highest image quality of all the canons, with the smallest photosites. Less of the uninformed armchair technological analysis posing as real technological understanding.
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DR-enhancing sensor technology is not standing still. Take a look at the schematic of the new microlenses associated with the new sensor used on the 50D on the DPReview website.
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Lets wait to see some testing before we say it has less DR, technology changes, my P21 has no more DR than the P45 which has smaller photosites.
[a href=\"index.php?act=findpost&pid=217288\"][{POST_SNAPBACK}][/a]
Yes, but the point is that with a given technology larger photosites will basically always result in more DR. So if the DR of a 15MP is OK, you could have had an OK+ DR had they sticked to 12MP.
Cheers,
Bernard
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Yes, but the point is that with a given technology larger photosites will basically always result in more DR. So if the DR of a 15MP is OK, you could have had an OK+ DR had they sticked to 12MP.
Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=217291\"][{POST_SNAPBACK}][/a]
I would not make those generalizations. The 5D's DR is not much wider then the DR of any of the other DSLR models up and down the ladder, regardless of MP, and sensor size.
MP does in fact matter, if one is going to enlarge. I take the other view in that I do beleive MP does in fact matter. I'd rather have my frame cut into 15 million "pieces" then just 10 million. Of course going from 10 to 15mp is not a big jump in resolution however.
Although I do agree that DR is more important then MP count, and DR is perhaps the last "frontier" for all the DSLR makers.
Funny, over the the last 8+ year, DR has not widen much.
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Yes, but the point is that with a given technology larger photosites will basically always result in more DR. So if the DR of a 15MP is OK, you could have had an OK+ DR had they sticked to 12MP.
Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=217291\"][{POST_SNAPBACK}][/a]
I agree completely, Bernard. That is why I am very excited and anxious to see (and own) today's (50D?) technology spread across a FF sensor, hopefully soon in the 5D replacement.
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When you print, pixels matter. When you crop, pixels matter. When you print big, pixels matter more. I like to print really big images.
In my mind dynamic range is of similar importance. In landscape photography, blown highlights are the bane of my existence--probably yours too.
I want both specs to improve.
Canon has yet to put out a next generation camera where the image quality wasn't equal or better than the previous. Their achievements in the XSI as compared to the 40D make me optimistic that the 50D will continue the trend.
The quality where canon has consistently outclassed most of the other manufacturers has been general image quality, especially high ISO performance. I hope they will be smart enough not to do something stupid like compromise image quality (clarity/smoothness/sharpness/color/DR/whatever) for more pixels.
I guess we won't have to speculate and pontificate for much longer. We should see some real-world samples by October.
I also wouldn't mind if they scaled back the AA filter too. Maybe I will get a 50D and send my 30D off to have its AA filter removed.
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For landscape photography the increased MP will be useless. Stop down to f/11 and compare a 50D file to a 40D file; in terms of resolution there will be no difference.
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DR-enhancing sensor technology is not standing still. Take a look at the schematic of the new microlenses associated with the new sensor used on the 50D on the DPReview website.
How would microlenses contribute to the dynamic range? They do contribute to the "sensitivity" of the sensor, but not to the DR.
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How would microlenses contribute to the dynamic range? They do contribute to the "sensitivity" of the sensor, but not to the DR.
[a href=\"index.php?act=findpost&pid=217314\"][{POST_SNAPBACK}][/a]
>SNR => <amplification for a given ISO => lower noise => >usable dynamic range
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MP's are important, you can't scale a canon file up much at all before you get significant degradation. I don't need a lot, really around 15 is fine for most of my needs. DR has never been an issue to me with canon files, the big thing that upsets me is the lack of sharpness. If only they'd back off on the AA filter.
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For landscape photography the increased MP will be useless. Stop down to f/11 and compare a 50D file to a 40D file; in terms of resolution there will be no difference.
[a href=\"index.php?act=findpost&pid=217312\"][{POST_SNAPBACK}][/a]
Why, exactly?
Every increase in resolution I've been given has been visible. I shoot a lot of prairie shots. Grass is a bitch. Pixels help.
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Love the competion.
Isn't that great. For years we've (canon users) have said we welcomed competition because it would drive canon. It finally looks like that might be true.
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>SNR => <amplification for a given ISO => lower noise => >usable dynamic range
There is no connection to microlenses.
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the big thing that upsets me is the lack of sharpness. If only they'd back off on the AA filter.
[a href=\"index.php?act=findpost&pid=217316\"][{POST_SNAPBACK}][/a]
What raw processor are you using? I would not say there is a lack of sharpness with processing Canon files with Raw Developer.
Doyle
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Why, exactly?
Every increase in resolution I've been given has been visible. I shoot a lot of prairie shots. Grass is a bitch. Pixels help.
[a href=\"index.php?act=findpost&pid=217317\"][{POST_SNAPBACK}][/a]
I guess Tony is referring to the detrimental effect difraction has on actual system resolution. It is reasonable to expect that difraction will raise its head earlier than on cameras with larger pixel pitch. We will just have to wait and see if the difference will be noticeable.
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For landscape photography the increased MP will be useless. Stop down to f/11 and compare a 50D file to a 40D file; in terms of resolution there will be no difference.
[a href=\"index.php?act=findpost&pid=217312\"][{POST_SNAPBACK}][/a]
Your statement is exceedling far from the truth. For landscapes, MP matters. Lots.
Or perhaps you just print 4" x 6" prints?
What does F11 have to do with resolution and/or MP?
Nothing, unless a caca lense provides too early diffraction, yea? Usually that happens at F16 or down from there, lens depending.
For landscapes, one cannot get enough MP. Of course DR is more important, but lets not throw the MP out with the bathwater.
By the way at 16" x 20" prints, you will see a difference between 40D & 50D.
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What does F11 have to do with resolution and/or MP?
Nothing, unless a caca lense provides too early diffraction, yea? Usually that happens at F16 or down from there, lens depending
You may be an expert in caca issues, but you need to catch up a bit regarding diffraction.
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You may be an expert in caca issues, but you need to catch up a bit regarding diffraction.
[a href=\"index.php?act=findpost&pid=217335\"][{POST_SNAPBACK}][/a]
Perhaps you need to catch up on how MP, and sensor size can benefit landscapes, and how they effect enlargements ;-)
In other words, MP does in fact matter.
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What raw processor are you using? I would not say there is a lack of sharpness with processing Canon files with Raw Developer.
Doyle
[a href=\"index.php?act=findpost&pid=217327\"][{POST_SNAPBACK}][/a]
I usually use DPP though I have used Raw developer and it is really very good, though DPP is only a hair away from it. I still find sharpness to be lacking though for the look I want. You should see a phase P21 file with Raw developer.
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In other words, MP does in fact matter.
I did not mention MP at all. In fact, higher MP is making diffraction worse. Judged from the 40D, diffraction will be strongly noticable on the 50D already at f/11.
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I did not mention MP at all. In fact, higher MP is making diffraction worse. Judged from the 40D, diffraction will be strongly noticable on the 50D already at f/11.
[a href=\"index.php?act=findpost&pid=217350\"][{POST_SNAPBACK}][/a]
How about we wait for the thing to come out and we'll see some tests eh? These hypothetical pseudo-scientific discussions get a little tiresome.
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How about we wait for the thing to come out and we'll see some tests eh? These hypothetical pseudo-scientific discussions get a little tiresome.
You should simply ignore the subjects you don't understand.
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How about we wait for the thing to come out and we'll see some tests eh? These hypothetical pseudo-scientific discussions get a little tiresome.
[a href=\"index.php?act=findpost&pid=217353\"][{POST_SNAPBACK}][/a]
I couldn't agree more! It is amazing how we can take the fun and excitement out of a new product announcement by speculating about how crappy it is going to be based upon "hypothetical pseudo-scientific" criteria. (Great term woof75)
There are lots of great features that we can discuss in a more deterministic way.
I am pleased to see a higher resolution LCD. I have always thought that great displays go a long way to improving usability of a product, whether it is a phone, laptop, TV, or a camera.
The micro-focus feature looks really cool too. The ability to calibrate my lenses to my body could improve focus results, particularly for things like macro or other very shallow depth of field applications.
I am using a 30D and perhaps the most desirable feature to me is the viewfinder display of the ISO. I can't tell you how many times I have accidentally shot at too high an ISO. ( I know that was in the 40D.)
Adjustable noise reduction sounds good, especially if I am shooting jpg candids that I don't intend to post-process.
It appears that with the custom menus the user will be able to move the mirror lockup function farther up out of the bowels of the menu-system....I guess that is progress.
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The micro-focus feature looks really cool too. The ability to calibrate my lenses to my body could improve focus results, particularly for things like macro or other very shallow depth of field applications.
I'm betting its main use will be by idiots who will screw with it for days and weeks before resetting it to 0.
It appears that with the custom menus the user will be able to move the mirror lockup function farther up out of the bowels of the menu-system....I guess that is progress.
[a href=\"index.php?act=findpost&pid=217358\"][{POST_SNAPBACK}][/a]
You can do that on the 40D. But turning live view on serves much the same purpose as MLU with the added advantage that you can pick the opportune time to hit the shutter.
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You should simply ignore the subjects you don't understand.
[a href=\"index.php?act=findpost&pid=217356\"][{POST_SNAPBACK}][/a]
I do and you should too.
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I'm betting its main use will be by idiots who will screw with it for days and weeks before resetting it to 0.
....
[a href=\"index.php?act=findpost&pid=217359\"][{POST_SNAPBACK}][/a]
The optimism around here is positively infectious.
Another feature that I like the sound of is the ability to take smaller RAW images, particularly if it is part of a tradeoff with very high ISOs. If I am taking indoor, nighttime, available-light photos, I am very willing to lower the resolution to have an image with lower noise. Sounds like a trade I would take any day. I can see using this for family gatherings or events with my 50 f/1.4 when I am using my camera in a completely different modality than when I hike in the wilderness with a long lens and a tripod. This gives the camera a split-personality that I think increases flexibility.
Highlight tone priority is another one that has me curious. I can see looking at a snow-scene or a waterfall and thinking that I want to get the whites perfect and let everything else fall where it will. That might produce some decent results.
I will assume that this new camera will build upon the success of the 40D quality until we have image samples that prove it is inferior. Otherwise, all we have is a case of preemptive, premature pixel-peeping.
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*clip*
I will assume that this new camera will build upon the success of the 40D quality until we have image samples that prove it is inferior. Otherwise, all we have is a case of preemptive, premature pixel-peeping.
[a href=\"index.php?act=findpost&pid=217361\"][{POST_SNAPBACK}][/a]
I'm not going to assume anything about it. I need to see reviews of this one.
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Your statement is exceedling far from the truth. For landscapes, MP matters. Lots.
Or perhaps you just print 4" x 6" prints?
What does F11 have to do with resolution and/or MP?
Nothing, unless a caca lense provides too early diffraction, yea? Usually that happens at F16 or down from there, lens depending.
For landscapes, one cannot get enough MP. Of course DR is more important, but lets not throw the MP out with the bathwater.
By the way at 16" x 20" prints, you will see a difference between 40D & 50D.
[a href=\"index.php?act=findpost&pid=217331\"][{POST_SNAPBACK}][/a]
While the 50D looks like a VERY nice camera, I can assure you that you'll be treading into diffraction limited waters once near or past F/8 and purely from a resolution standpoint, if you shot the 40D and 50D at F/11, you'd quite likely end up with about the same overall resolution simply because of the pixel pitch of the higher MP sensor in the same APS-C space. Has nothing to do with the lens at this point.
I shoot on the other side (Nikon) with the D2X and can absolutely tell you that F/11 is the limit (probably more like F/10 if you're really critical) before diffraction robs you of sharpness - and that's with some of the very best glass Nikon makes (200/2 VR, etc), so it's not the glass - it's the pixel pitch of the sensor. This is commonly known - I'm not just talking out of my head or making something up to slam a competing brand. If Nikon comes out with a 15mp DX framed camera I'd be saying the exact same thing - in the cropped sensor, 12mp is about the sweet spot for a landscape shooter IMO.
So that's the big problem - not just with Canon, but with anyone (Nikon, Pentax, whomever) who is trying to move beyond about 12mp on a DX/APS-C cropped sensor - the pixel pitch is getting too bloody small and diffraction rears it's ugly head.
And we won't get into the higher demands on the lenses (you think the less-than-spectacular Canon wide zooms are going to shine on a 50D?) and also focus accuracy and problems with subject/camera movement. High pixel density is nice *when* you get everything right, but it requires far more technical discipline out of the photographer and requires that everything in the "chain", from support system to aperture (that isn't in diffraction city) to focus to technique is optimized or you'll never realize the full megapixel capability fo the camera. And that's with any brand - again, I'm not just picking on Canon here.
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Ultimately what I do hope is that Canon takes the sensor *technology* from the 50D and applies it in the 5D replacement. The thought of a FF camera that's affordable (relative to the 1ds-III) and maybe 18-20mp with a very nicely done sensor is somewhat of a holy grail amongst landscape folks, I think. Such a beast won't be so problematic in terms of pixel density/diffraction problems, yet it still will have decent resolution, and hopefully have nice DR. That's preferable (getting the combination correct) versus just playing marketing megapixels...
YMMV of course.
-m
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Highlight tone priority is another one that has me curious. I can see looking at a snow-scene or a waterfall and thinking that I want to get the whites perfect and let everything else fall where it will. That might produce some decent results
You don't need to wait for any camera to achieve the same. Simply reduce the exposure by one stop, that is namely what HTP does.
Or better, you can reduce the expoxure by 1/3 or 2/3 stop and lose less of the dynamic range.
Even better, you can change to a setting, which makes the in-camera histograms resembling the raw histograms; thus you can expose "perfectly" (the technic does not guarantee a correct exposure, it only guarantees, that you can *see if* the exposure was correct).
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You don't need to wait for any camera to achieve the same. Simply reduce the exposure by one stop, that is namely what HTP does.
Or better, you can reduce the expoxure by 1/3 or 2/3 stop and lose less of the dynamic range.
Even better, you can change to a setting, which makes the in-camera histograms resembling the raw histograms; thus you can expose "perfectly" (the technic does not guarantee a correct exposure, it only guarantees, that you can *see if* the exposure was correct).
[a href=\"index.php?act=findpost&pid=217374\"][{POST_SNAPBACK}][/a]
Obviously I can manually manipulate the exposure to get a perfect histogram. I do that already. This feature may make it a bit quicker and easier.
If I understand the idea, this is like looking at your photo and picking out a pure white location and metering that instead of finding something 17% gray and metering on that. By using the white reference instead of the 17% gray, you guarantee a well exposed image that generally follows the expose to the right rule.
You don't need to wait for any camera to achieve the same. Simply reduce the exposure by one stop, that is namely what HTP does.[a href=\"index.php?act=findpost&pid=217374\"][{POST_SNAPBACK}][/a]
I think you are over-simplifying. In some cases it might reduce the exposure, in others, it might increase the exposure.
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I think you are over-simplifying. In some cases it might reduce the exposure, in others, it might increase the exposure.
I was one of the first analyzing the effect of HTP with the 40D on the unadultered raw data. There is nothing special about that: it simply reduces the effective ISO by one stop (that's the reason it does not work with ISO 100). As the exposure remains unchanged, this is equivalent to underexposing the shot by one stop. Of course the intention is not underexposure but prevention of overexposure.
HTP is for JPEG, not for raw.
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Wow. This camera is really getting noticed. Right on the front page of google news from cnet:
http://news.cnet.com/8301-13580_3-10025886-39.html (http://news.cnet.com/8301-13580_3-10025886-39.html)
I thought my 40D was killer deal... especially at f/8, on tripod, MLU and timer, bracket exposure, pan and stitch up to 6 shots together to create a monster 40" print of some 50-60 MP.
I guess with 12500 ISO I can tape shut the flash door.
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15MP on an APS-C sensor? Isn't that overkill? Didn't Canon learn their lesson with the 1DSMK3?
My guess is as long as the manufacturers can convince the lemmings they need more megapixels, they'll continue down this silly path, while real improvements will trickle in slowly.
I'm one of the Lemmings, the 1DsmkIII is a cracking camera and yes I'd have more pixels if they were available. The 1DsmkIII 21mp work really well.
Kevin.
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I guess with 12500 ISO I can tape shut the flash door.
The highest real ISO of the 40D is 1600. The 50D may get 3200, but 6400 and 12800 will be faked, i.e. almost the same as to boosting the "exposure" in post processing (but the fake ISOs are reducing the DR). The Nikon D3 with much larger pixels goes up to 6400.
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Your statement is exceedling far from the truth. For landscapes, MP matters.[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=217331\")
[a href=\"http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm]http://www.cambridgeincolour.com/tutorials...photography.htm[/url]
Read and learn, and then you can do what Thom Hogan and others (including myself) have done, and do comparisons between various pixel pitch DSLRs at various apertures and see for yourself.
(http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/websize/DSC_4605_1%20copy.jpg)
As you can see, a 12 MP DSLR was reduced to no better than a 6 MP DSLR at f/16; I'm not sure why the 12 MP DSLR pulls ahead at f/22 (probably a smoother shutter), but since they both look like crap I hardly care.
As recently as today, Thom Hogan has posted at DPR on this very topic: http://forums.dpreview.com/forums/read.asp...essage=29080207 (http://forums.dpreview.com/forums/read.asp?forum=1000&message=29080207)
By the way at 16" x 20" prints, you will see a difference between 40D & 50D.
You must have done direct comparisons to make such a bold statement. Why do I think you are blowing smoke?
The issue will be at f/11, and I will bet you that at f/8 you will see an improvement but at f/11 the 40D will pull even with the 50D because the 50D will have become diffraction limited at f/8.
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There is no connection to microlenses.
[a href=\"index.php?act=findpost&pid=217320\"][{POST_SNAPBACK}][/a]
Tell Canon.
(From PDN interview with Chuck Westfall...)
Westfall said one of the keys about the 50D is its enhanced noise reduction which is "a stop to a stop and half better than the 40D."
"Despite the fact that the pixels are smaller and one camera has a 10.1MP sensor and the other has a 15.1MP sensor, you'd think you'd have more noise but you have less," he said. "The end result is better image quality all around which allows us to extend the ISO range to 12800.
The 50D is able to achieve this because of new "gapless microlenses" on the image sensor which capture more light and generate less noise.
"It's the further evolution of a concept we've already explored. It's gotten to the point where the microlenses are totally gapless and larger which produces the best efficency on a per pixel basis. Consequently the light senstiviy portion of the pixel has increased while the non-light sensitive protion of the pixel has been shrunk down," he said. "Another part of the reason you have a cleaner signal coming out is DIGIC 4 is considerable more powerful than the DIGIC 3 and offers better noise reduction."
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"Despite the fact that the pixels are smaller and one camera has a 10.1MP sensor and the other has a 15.1MP sensor, you'd think you'd have more noise but you have less," he said. "The end result is better image quality all around which allows us to extend the ISO range to 12800.
The 50D is able to achieve this because of new "gapless microlenses" on the image sensor which capture more light and generate less noise
This is all right, but it does not translate in higher dynamic range. Capturing more light in the same time causes a shift on the ISO scale: the number of photons required can be collected in shorter time - BUT the wells will become full sooner as well. In other words, not only the lower but the higher end of the dynamic range moves as well.
In order to increase the dynamic range, either the well capacity has to be increased or the required number of photons decreased; none of these has to do with microlenses. It is like with the aperture: a larger aperture allows capturing the required number of photons in shorter time, while at the same time saturation too will occur in shorter time.
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In order to increase the dynamic range, either the well capacity has to be increased or the required number of photons decreased; none of these has to do with microlenses.[a href=\"index.php?act=findpost&pid=217428\"][{POST_SNAPBACK}][/a]
Since there is more absolute DR than there is useful DR (in all the DSLRs I'm aware of), noise is a more limiting factor than well capacity.
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While the 50D looks like a VERY nice camera, I can assure you that you'll be treading into diffraction limited waters once near or past F/8 and purely from a resolution standpoint, if you shot the 40D and 50D at F/11, you'd quite likely end up with about the same overall resolution simply because of the pixel pitch of the higher MP sensor in the same APS-C space. Has nothing to do with the lens at this point.
[a href=\"index.php?act=findpost&pid=217370\"][{POST_SNAPBACK}][/a]
All true, but we will be close to that soon with FX too.
The fact is that we are at levels of resolution on "small sensors" that is such that it now clearly impossible to get both a lot of DoF and very good sharpness.
The only 2 options are:
1. T/S lenses
2. Digital DoF stacking.
I have been using 2. for years and it works a treat for landscape work.
As far as the 50D goes, I personnally welcome Canon's willingness to keep pushing the DX enveloppe further. The need to use f8 to shoot at optimal sharpness is not a problem in itself. You will still always have a better sharpness/DoF compromise with DX than with FX.
As mentioned above though, my personnal feeling is that it would have been better to push the DX enveloppe towards more DR at same pixel count, but this opinion is not derived from the fact that more pixels mean more diffraction.
Cheers,
Bernard
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Since there is more absolute DR than there is useful DR (in all the DSLRs I'm aware of), noise is a more limiting factor than well capacity.
The dynamic range, as its name suggests, has to "ends". Neither end is more limiting than the oder, for the range is the distance between these ends.
Anyway, if Canon in fact could enhance the noise characteristics of the sensor, that increases the dynamic range. However, that has nothing to do with the microlenses.
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Since there is more absolute DR than there is useful DR (in all the DSLRs I'm aware of), noise is a more limiting factor than well capacity.
[a href=\"index.php?act=findpost&pid=217432\"][{POST_SNAPBACK}][/a]
There should be no such things as "DR" and "useful DR". If DR is not useful then the definition of DR in terms of the level of noise in the shadows from which there is no detail is wrong.
DR is often confused with highlight rollout.
The recent sensors, at least from Nikon that I know better, are doing a much better job at having a smooth transition to blown out areas. This is not the result of more DR, but is the result of a better sensor design coupled with more bits to handle the very bright parts of the image.
DR shows mostly in the shadows of most DSLRs (the onlyt exception being the Fuji S5) in terms of how much you can lighten up the shadows without getting un-acceptable noise.
Cheers,
Bernard
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The recent sensors, at least from Nikon that I know better, are doing a much better job at having a smooth transition to blown out areas. This is not the result of more DR, but is the result of a better sensor design coupled with more bits to handle the very bright parts of the image
There is no "smooth transition" to pixel saturation. The sensors of the Nikon cameras do not behave differently from any other: the recorded pixel values are linear (if one adjusts for a floating start), up to the saturation.
However, the camera's software or the raw conversion can cause such an effect; see HTP with Canons, and I think Active Daylight is doing something similar (though it does not seem to reduce the ISO as HTP does).
DR shows mostly in the shadows of most DSLRs (the onlyt exception being the Fuji S5) in terms of how much you can lighten up the shadows without getting un-acceptable noise
When I am stating, that I am not interested for the highlights when measuring the DR, only for the very deep shadows, some people think I am joking. I need only a very dark shot (with suitable subjects) to measure the DR.
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There is no "smooth transition" to pixel saturation. The sensors of the Nikon cameras do not behave differently from any other: the recorded pixel values are linear (if one adjusts for a floating start), up to the saturation.
[a href=\"index.php?act=findpost&pid=217447\"][{POST_SNAPBACK}][/a]
I'll have to disagree with you on this one.
The sensor technology does clearly influence the way subtely different very bright illuminations level are translated into RGB values.
Cheers,
Bernard
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This is all right, [span style=\'font-size:14pt;line-height:100%\']but it does not translate in higher dynamic range.[/span] Capturing more light in the same time causes a shift on the ISO scale: the number of photons required can be collected in shorter time - BUT the wells will become full sooner as well. In other words, not only the lower but the higher end of the dynamic range moves as well.
In order to increase the dynamic range, either the well capacity has to be increased or the required number of photons decreased; none of these has to do with microlenses. It is like with the aperture: a larger aperture allows capturing the required number of photons in shorter time, while at the same time saturation too will occur in shorter time.
[a href=\"index.php?act=findpost&pid=217428\"][{POST_SNAPBACK}][/a]
[span style=\'font-size:11pt;line-height:100%\']Let's take it one more time, from the top, with the important portions of the Canon statement highlighed for emphasis:[/span]
Westfall said one of the keys about the 50D is its [span style=\'font-size:14pt;line-height:100%\']enhanced noise reduction [/span]which is "a stop to a stop and half better than the 40D."
"Despite the fact that the pixels are smaller and one camera has a 10.1MP sensor and the other has a 15.1MP sensor, you'd think you'd have more noise but you have less," he said. "The end result is better image quality all around which allows us to extend the ISO range to 12800.
The 50D is able to achieve this because of new [span style=\'font-size:14pt;line-height:100%\']"gapless microlenses" on the image sensor which capture more light and generate less noise[/i].[/span]
"It's the further evolution of a concept we've already explored. It's gotten to the point where the microlenses are totally gapless and larger which produces the best efficency on a per pixel basis. [span style=\'font-size:14pt;line-height:100%\']Consequently [span style=\'font-size:21pt;line-height:100%\']the light sensitive portion of the pixel has increased [/span]while the non-light sensitive portion of the pixel has been shrunk down,"[/b][/span] he said.
[span style=\'font-size:11pt;line-height:100%\']Gapless microlense => larger pixel possible => bigger well + higher SNR;
Bigger well + higher SNR => greater dynamic range;
=> Canon's new "gapless microlense" sensor (presumably) has greater dynamic range.
(Let's play "connect the dots.")[/span]
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There should be no such things as "DR" and "useful DR". If DR is not useful then the definition of DR in terms of the level of noise in the shadows from which there is no detail is wrong.[a href=\"index.php?act=findpost&pid=217445\"][{POST_SNAPBACK}][/a]
Well, different photographers define the DR they are willing to use coming from the same camera differently. Ironically, they also define useful ISO differently -- that's because ISO and DR are essentially the same issue, which is how much noise is acceptable to you and that cannot be quantified whereas absolute DR can be quantified.
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The sensor technology does clearly influence the way subtely different very bright illuminations level are translated into RGB values
There is no such thing. The sensors' output is strictly linear (disturbed somewhat by the noise).
See the attached captures from a D3 shot of a Stouffer wedge. The strips are roughly 1/3 stop apart, this is visible on the histogram as well. The next captures show the average pixel values on a selected spot of adjacent strips. You only need to divide the pixel values to see the scheme.
Sidenote: the raw pixel values are not RGB. They could be characterized as Rgb, Grb, Brg.
I don't know why the captures do not appear in the sequence I uploaded them. The sequence of the numbered strips are 4, 5, 6, 7, starting from the brightest one.
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Let's take it one more time, from the top, with the important portions of the Canon statement highlighed for emphasis
I'm afraid you are reading too much into a propaganda communiqué. Canon and Mr. Westfall are extremely selective with any technical information. (Example: they were not prepared to reveal the way HTP is working - like it would be some information worthy for keeping secret.)
I suggest to use some reasoning. For example: by mounting a large ancilliary lens on the camera's lens' front, one could increase the amount of captured light. This would lead to an increase of the nominal ISO. Would this increase the DR as well?
Of course, the larger/more effective microlenses increase the amount of captured light. This leads to less noise compared to a shot with teh same exposure but less effective microlenses. However, again, this leads to earlier saturation as well.
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I did not mention MP at all. In fact, higher MP is making diffraction worse. Judged from the 40D, diffraction will be strongly noticable on the 50D already at f/11.
[a href=\"index.php?act=findpost&pid=217350\"][{POST_SNAPBACK}][/a]
Gabor,
If I may say so without causing offense, I get the impression that all this pixel-peeping has resulted sometimes in your not being able to see the wood for the trees.
System resolution is generally a combination of lens resolution and film or sensor resolution. If the resolution of either one is increased, whilst keeping the other the same, the result will likely (but not necessarily) still be a modest increase in system resolution, depending on other factors such as the strength of the AA filter.
An example of this principle in its most basic form would be as follows.
If a lens at a particular aperture delivers a resolution of 50 lp/mm at 50% MTF, and the sensor also can record 50 lp/mm with a loss of 50% contrast, then the system resolution would be 1/(1/50 +1/50) = 25lp/mm at 50% MTF.
However, if we increase sensor resolution by increasing pixel count, so that the sensor is capable of recording 100 lp/mm at 50% MTF, then the system resolution using the same lens at the same aperture is given by 1/(1/100+1/50) = 33 lp/mm.
However, I believe such formulas are very rough approximations because of the role of the AA filters and demosaicing algorithms.
Nevertheless, my own tests have indicated that a 20D with with the 100-400 IS zoom at 400mm and F22 can produce marginally more detailed results than the same lens at the same aperture on the 5D (shooting the same scene from the same position). I would therefore expect that a 50D with the same lens at the same aperture of F22 would also produce marginally more detailed results than the 20D to a degree which might be significant on large prints.
However, the difference between the 50D and 450D in this respect will likely be inconsequential. BJL mentioned in another thread, resolution will never be worse as a consequence of greater pixel count, whatever the aperture, but this might not be true if one is comparing different systems, such as the Olympus E-3 with the Canon 40D.
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System resolution is generally a combination of lens resolution and film or sensor resolution. If the resolution of either one is increased, whilst keeping the other the same, the result will likely (but not necessarily) still be a modest increase in system resolution, depending on other factors such as the strength of the AA filter
Great. Now, we have a case, where the sensor resolution is increased, while the lens resolution decreases due to diffraction.
This is apart from the fact, that the formula you used in your calculation is though widely circulated, but useless, i.e. not applicable. Nothing, but really nothing can make up for the loss caused by the lens.
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Of course, the larger/more effective microlenses increase the amount of captured light. This leads to less noise compared to a shot with teh same exposure but less effective microlenses. However, again, this leads to earlier saturation as well.
[a href=\"index.php?act=findpost&pid=217467\"][{POST_SNAPBACK}][/a]
Gabor,
I think this is another example of your not seeing the woods for the trees. You seem to be too concerned with the performance of the individual pixel or sentel at the expense of the over all image. What's important with regard to the final result, is the performance per unit area of sensor.
At the pixel level, each one of 4 small sentels, taken individually, are almost certainly going to be noisier and have less DR than one big pixel covering the same area as the 4 smaller pixels. However, from the perspective of the image as a whole, we're interested in how the 4 smaller pixels (as a group) compare with the one larger pixel covering the same area.
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At the pixel level, each one of 4 small sentels, taken individually, are almost certainly going to be noisier and have less DR than one big pixel covering the same area as the 4 smaller pixels. However, from the perspective of the image as a whole, we're interested in how the 4 smaller pixels (as a group) compare with the one larger pixel covering the same area.
Ray,
I am not participating in your attempts to convert a camera into another one. If I buy a 15 Mpix camera, then I don't compare that with a 2 Mpix, because I don't want to downres the images. If I wanted to, then I would buy another camera instead of the 15 mpix.
In other words: four pixels are not one pixel.
(I do not intent to buy the 50D; I am with Bernard: I need more DR, not more pixels. And no, I am not interested in converting the DR into something else.)
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Great. Now, we have a case, where the sensor resolution is increased, while the lens resolution decreases due to diffraction.
This is apart from the fact, that the formula you used in your calculation is though widely circulated, but useless, i.e. not applicable. Nothing, but really nothing can make up for the loss caused by the lens.
[a href=\"index.php?act=findpost&pid=217473\"][{POST_SNAPBACK}][/a]
Any decrease in lens resolution has nothing to do with pixel count. Lens resolution is dependent on lens quality and aperture selected.
If we are comparing same size sensors, then choice of aperture will be very closely the same for same DoF whatever the pixel count, but not exactly the same.
If we are comparing different size sensors, then choice of aperture will be different for same DoF in accordance with the crop factor.
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...resolution will never be worse as a consequence of greater pixel count, whatever the aperture[a href=\"index.php?act=findpost&pid=217469\"][{POST_SNAPBACK}][/a]
No, but resolution won't be any better when you hit the diffraction wall. Lots of consumers are going to be scratching their heads when they don't see any improvement going from a 40D to a 50D shooting at f/11.
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Ray,
I am not participating in your attempts to convert a camera into another one. If I buy a 15 Mpix camera, then I don't compare that with a 2 Mpix, because I don't want to downres the images. If I wanted to, then I would buy another camera instead of the 15 mpix.
In other words: four pixels are not one pixel.
(I do not intent to buy the 50D; I am with Bernard: I need more DR, not more pixels. And no, I am not interested in converting the DR into something else.)
[a href=\"index.php?act=findpost&pid=217477\"][{POST_SNAPBACK}][/a]
Gabor,
You seem to have misunderstood my analogies. I'm comparing a large pixel with 4 small pixels (or a 3mp sensor with a 12mp sensor) for the sake of simplicity and in order to highlight an underlying principle.
In practice, these incremental increases in pixel count from Canon are like comparing one small pixel with a previous one just 1.2x the size. But the principle is the same. If you apply a bit of new technology, such as reducing the gap between microlenses, reducing the effect of extraneous noise within the system, reducing the size of on-chip processing devices (whatever they may be), then you can end up with a camera capable of producing improved image quality.
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Any decrease in lens resolution has nothing to do with pixel count. Lens resolution is dependent on lens quality and aperture selected
Lens resolution has to do a lot with pixel resolution (not with pixel count), namely if the lens does not resolve enough, then the high pixel resolution is useless.
I'm comparing a large pixel with 4 small pixels (or a 3mp sensor with a 12mp sensor) for the sake of simplicity and in order to highlight an underlying principle
I find these comparisons irrelevant and your underlying principles misguided, just like your mixing up the circle of confusion with sensor size.
However, I do not intend to convince you from the correctness of my viewpoint.
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There is no such thing. The sensors' output is strictly linear (disturbed somewhat by the noise).
[a href=\"index.php?act=findpost&pid=217465\"][{POST_SNAPBACK}][/a]
My experience with previous DSLR (starting with the D2x) clear shows that the sensor is not linear in the .1 brighest stop where it matter most. This wouldn't show in your test that does not focus on very bright illuminations like those found at the edge of the sun for instance.
The D3 does improve a lot on this.
Cheers,
Bernard
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I'm afraid you are reading too much into a propaganda communiqué. Canon and Mr. Westfall are extremely selective with any technical information. (Example: they were not prepared to reveal the way HTP is working - like it would be some information worthy for keeping secret.)
I suggest to use some reasoning. For example: by mounting a large ancilliary lens on the camera's lens' front, one could increase the amount of captured light. This would lead to an increase of the nominal ISO. Would this increase the DR as well?
Of course, the larger/more effective microlenses increase the amount of captured light. This leads to less noise compared to a shot with teh same exposure but less effective microlenses. However, again, this leads to earlier saturation as well.
[a href=\"index.php?act=findpost&pid=217467\"][{POST_SNAPBACK}][/a]
I give up.
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Lens resolution has to do a lot with pixel resolution (not with pixel count), namely if the lens does not resolve enough, then the high pixel resolution is useless.
Lens resolution cannot be measured by recording images on a digital sensor or film, hence the limitation of the sort of test results one finds at Photozone where one is correctly advised that one should not compare different systems in order to understand the quality of the lens.
Traditionally, lens resolution used to be measured by projecting an image of a line chart onto a very fine screen and then employing someone to count the visible lines using a microscope. As soon as you attempt to record the image (whether the image is of a line chart or any real-world scene) the image is degraded by the recording medium, whether that's film or sensor.
Recorded images provide you with 'system' resolution. It is of course possible to make certain deductions about the lens, from such recorded images, if you know the qualities of the recording medium.
I find these comparisons irrelevant and your underlying principles misguided, just like your mixing up the circle of confusion with sensor size.
The underlying principle is not misguided. It's simply an underlying principle. It's application may be misguided. However, as I've already mentioned, I have observed in my own shooting a marginal increase in detail with the 20D at F22 compared with the same scene taken with the 5D with the same lens at the same aperture (cropped to the 20D FoV).
However, I do not intend to convince you from the correctness of my viewpoint.
Tony Beach has already provided some photographic examples demonstrating that your hypothesis is not correct.
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No, but resolution won't be any better when you hit the diffraction wall. Lots of consumers are going to be scratching their heads when they don't see any improvement going from a 40D to a 50D shooting at f/11.
[a href=\"index.php?act=findpost&pid=217479\"][{POST_SNAPBACK}][/a]
Tony,
There's no diffraction wall. It's more like a forest that gets denser and thicker the further you penetrate (the more you stop down).
There's a progression from apertures at which non-diffraction aberrations predominate, to apertures at which diffraction effects predominate.
In order to very precisely realise the full resolution potential of any lens at any aperture, you would ideally need the perfect sensor with infinite resolution at 100% MTF. Of course, we don't need (and can never get) anywhere near such precision as photographers, but any improvement in either lens or sensor is welcome.
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My experience with previous DSLR (starting with the D2x) clear shows that the sensor is not linear in the .1 brighest stop where it matter most.
I wonder how you came to this result. I have (and have analyzed) D2X images as well, with much clipping, and never seen anything like that.
There exists a special kind of non-linearity: many sensors of Nikon, Canon as well, exhibit a strange behaviour, and this depends not only on the model but on the individual copies as well: different pixels have different saturation points. I demonstrated this in the Rawnalyze handbook, see http://www.cryptobola.com/PhotoBola/RawnalyzeGuideAll.htm (http://www.cryptobola.com/PhotoBola/RawnalyzeGuideAll.htm), Exposure Display; the example is from a D200.
This range, in the example from 3995 to 4025 is practically useless. Nevertheless, the individual pixels still yield linear values.
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Check out emil's explanation in the second post of this thread (http://www.naturescapes.net/phpBB3/viewtopic.php?f=2&t=137683) I found it helpful
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http://www.cambridgeincolour.com/tutorials...photography.htm (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm)
Read and learn, and then you can do what Thom Hogan and others (including myself) have done, and do comparisons between various pixel pitch DSLRs at various apertures and see for yourself.
(http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/websize/DSC_4605_1%20copy.jpg)
As you can see, a 12 MP DSLR was reduced to no better than a 6 MP DSLR at f/16; I'm not sure why the 12 MP DSLR pulls ahead at f/22 (probably a smoother shutter), but since they both look like crap I hardly care.
As recently as today, Thom Hogan has posted at DPR on this very topic: http://forums.dpreview.com/forums/read.asp...essage=29080207 (http://forums.dpreview.com/forums/read.asp?forum=1000&message=29080207)
You must have done direct comparisons to make such a bold statement. Why do I think you are blowing smoke?
The issue will be at f/11, and I will bet you that at f/8 you will see an improvement but at f/11 the 40D will pull even with the 50D because the 50D will have become diffraction limited at f/8.
[a href=\"index.php?act=findpost&pid=217405\"][{POST_SNAPBACK}][/a]
Tony, the point where diffraction effect is noticeable is a function of both the lens and the pixel pitch. A lens 'causes' diffraction, the sensor, depending on its pixel pitch, is able to record this or not. Diffraction limits the resolution of any lens AT THE POINT where other optical aberrations do not limit resolution much more than diffraction does.
What this all amounts to is that, yes, a smaller pitched sensor will show the effects of diffraction earlier BUT the diffraction effect itself will depend on the lens used. So at what point diffraction effects will equalize the system resolution between the 40D and the 50D will depend on the lens.
In practice though and with average lenses that are not diffraction limited until they reach quite a small aperture, the effect will be as you describe. That will not be true though with very high quality lenses which are diffraction limited at very large apertures. Which, I guess, is a very convoluted way of saying that the higher the pixel pitch the better lenses must be used to show off the MP advantage.
All this is well known to us Nikon users who have had the chance of using the D2x.
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Tony,
There's no diffraction wall.[a href=\"index.php?act=findpost&pid=217489\"][{POST_SNAPBACK}][/a]
I wonder if you read the links provided in post #39. Anyway, whether you did or not, I don't really care because I know what I have seen with my own eyes and I provided visual proof in that post that confirms the theory and the observations of Thom Hogan and others.
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I wonder if you read the links provided in post #39. Anyway, whether you did or not, I don't really care because I know what I have seen with my own eyes and I provided visual proof in that post that confirms the theory and the observations of Thom Hogan and others.
[a href=\"index.php?act=findpost&pid=217501\"][{POST_SNAPBACK}][/a]
I think what Ray meant is that the effect is not some absolute limit like a cliff but more of a slope. Your post with the text image clearly shows a worsening of the sharpness just as the theory predicts, but not a 'wall' past which everything is immediately dreadful.
I'm pretty sure Ray was merely pointing this out rather than disputing the results, which, in the case of your post, show up quite clearly.
The term 'diffraction limit' does imply some sort of end point whereas in reality it is merely a gradual appearance of the effect to the point where it is subjectively unacceptable. 'Diffraction effect threshold' might be a clearer term.
In my view it's like DoF; it's not a clear cut range, just a gradual lessening of absolute sharpness to the point where it becomes visible.
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In practice though and with average lenses that are not diffraction limited until they reach quite a small aperture, the effect will be as you describe. That will not be true though with very high quality lenses which are diffraction limited at very large apertures. Which, I guess, is a very convoluted way of saying that the higher the pixel pitch the better lenses must be used to show off the MP advantage.
All this is well known to us Nikon users who have had the chance of using the D2x.
[a href=\"index.php?act=findpost&pid=217499\"][{POST_SNAPBACK}][/a]
What lens would you recommend I use?
Here's 100% crops from my Nikkor 14-24/2.8 at 19mm taken under rigorously controlled conditions (studio lights, solid tripod, MLU, shot in RAW and processed identically):
(http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/Aperture%20comparison.jpg)
I bet you can tell which side was f/11 and which side was f/16.
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In my view it's like DoF; it's not a clear cut range, just a gradual lessening of absolute sharpness to the point where it becomes visible.
[a href=\"index.php?act=findpost&pid=217504\"][{POST_SNAPBACK}][/a]
It is my contention that by the time you reach f/11, there will be no difference between a 40D file and a 50D file. I could be wrong primarily due to AA filter strength, but I'm convinced that the 50D is going to start being diffraction impaired at about f/8. Losing a third or even half your resolution over a stop will be significant, whether you would call that a "wall" or "gradual" is a matter of semantics. Anyway, I like your term "Diffraction effect threshold".
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What lens would you recommend I use?
Here's 100% crops from my Nikkor 14-24/2.8 at 19mm taken under rigorously controlled conditions (studio lights, solid tripod, MLU, shot in RAW and processed identically):
(http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/Aperture%20comparison.jpg)
I bet you can tell which side was f/11 and which side was f/16.
[a href=\"index.php?act=findpost&pid=217508\"][{POST_SNAPBACK}][/a]
This has no relevance to what I was talking about. Nobody is contesting the fact that diffraction effects are noticeable at very small apertures. The issue is when this has an equalizing effect between different pitched sensors.
BTW A top quality long lens like the 300 2.8 is the one to use for such tests as these tend to be difraction limited at wide apertures i.e. no significant resolution improvement is evident by closing down.
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DR is often confused with highlight rollout.
The recent sensors, at least from Nikon that I know better, are doing a much better job at having a smooth transition to blown out areas. This is not the result of more DR, but is the result of a better sensor design coupled with more bits to handle the very bright parts of the image.
Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=217445\"][{POST_SNAPBACK}][/a]
According to my tests with the Nikon D3, the tone curve remains linear up to clipping and clipping occurs abrubtly. Rolloff in the highlights and shadows is due to the tone curve applied by the raw converter. The top curves are from an ACR rendering with the tone curve set to linear (all settings on main panel = 0, point curve = linear). The second plot is from Capture NX using the Standard Picture Control.
[attachment=8092:attachment]
[attachment=8091:attachment]
Bill
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I think what Ray meant is that the effect is not some absolute limit like a cliff but more of a slope. Your post with the text image clearly shows a worsening of the sharpness just as the theory predicts, but not a 'wall' past which everything is immediately dreadful.
[a href=\"index.php?act=findpost&pid=217504\"][{POST_SNAPBACK}][/a]
Thanks for the clarification, Nick. That is exacly what I meant .
We should not forget the Rayleigh's derived formula which describes the resolution limits of a lens at a particular F stop, a limit which is of great interest to astronomers.
As I understand, in it's simplest form for those who are not mathematicians, as I am not, the resolution limit of a lens at a particular F stop, in terms of line pairs per mm, is given by the formula 1600/F stop.
For example, at F16 a lens can deliver as much (and actually more, I believe) as 1600/16 lp/mm, or 100 lp/mm.
On the basis of approximately 3 pixels per line, the new 50D is capable of only 73 or so lp/mm.
Now I know, even if the the 50D were a foveon sensor without AA filter and were capable of recording over 100 lp/mm, it still wouldn't be able to record those faint lines at F16 because the MTF of those lines is only about 9 or 10%. They've lost about 90% of their original contrast as a result of diffraction. Camera system noise, read noise and insufficient quantum efficiency would all conspire to bury such faint signals.
But what about detail at 70 lp/mm at F16 and say 25% MTF? If such detail is of sufficiently high contrast, glittering black specs in the sunshine, I wouldn't be surprised if the 50D were able to record them in circumstances where the 40D would not be able to, simply because the 40D does not have sufficient pixels and resolving power.
Below is what Norman Koren has to say on the subject. The bold italics are mine.
Lenses are sharpest between about two stops down from maximum aperture and the aperture where diffraction, an unavoidable consequence of physics, starts to dominate. For 35mm lenses, this is typically between f/5.6 (f/8 for slow zooms) and f/11. At large apertures, resolution is limited by aberrations (astigmatism, coma, etc.), which lens designers work valiantly to overcome. MTF wide open is almost always poorer than MTF at f/8.
Diffraction worsens as the lens is stopped down (the f-stop is increased). The equation for the Rayleigh diffraction limit, adapted from R. N. Clark's scanner detail page, is,
Rayleigh limit (line pairs per mm) = 1/(1.22 Nω)
N is the f-stop setting and ω = the wavelength of light in mm = 0.0005 mm for a typical daylight spectrum. (0.00055 mm is the wavelength of green light, where the eye is most sensitive, but 0.0005 mm may be more representative of daylight situations.) I've seen a simple rule of thumb, Rayleigh limit = 1600/N, which corresponds to ω = 0.000512 mm. The light circle formed by diffraction, known as the Airy disk, has a radius equal to1/(Rayleigh limit).
The MTF at the Rayleigh limit is about 9%. Significant Rayleigh limits are 149 lp/mm @ f/11, 102 lp/mm @ f/16, 74 lp/mm @ f/22, and 51 lp/mm @ f/32. Larry, an experienced lens designer, finds these numbers to be somewhat conservative because the Rayleigh limit is based on a spot, which has lower resolution than a band. His numbers of 125 lp/mm @ f/16 and 64 lp/mm @ f/32 are derived from a Kodak chart he contributed to Robert Monaghan's Lens Resolution Testing page.
Most lenses are aberration-limited (relatively unaffected by diffraction) at f/8 and below. The OTF (optical transfer function) curve in David Jacobson's Lens Tutorial shows how MTF (the magnitude of OTF) varies with spatial frequency for a purely diffraction-limited lens at f/22.
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It is my contention that by the time you reach f/11, there will be no difference between a 40D file and a 50D file. I could be wrong primarily due to AA filter strength, but I'm convinced that the 50D is going to start being diffraction impaired at about f/8. Losing a third or even half your resolution over a stop will be significant, whether you would call that a "wall" or "gradual" is a matter of semantics. Anyway, I like your term "Diffraction effect threshold".
[a href=\"index.php?act=findpost&pid=217510\"][{POST_SNAPBACK}][/a]
The emphasis on the "diffraction limitation threshold" is misleading, and results in the common misperception of diffraction limitation as a problem. I would turn it around and say that the key issue is instead "pixel pitch limitation" -- larger pixel size results in a wider range of apertures where the limiting factor in system resolution is the pixel size rather than the optics. The smaller the pixels, the smaller the range of apertures where the sensor is the limiting factor in resolution. Why is that a problem? The photographer should choose the aperture for the DOF needed in the image they envision, and if the sensor is not getting in the way of resolution so much the better.
One begins to see where Canon is headed with the 50D. Eventually, it seems likely they are going to offer APS-C or larger sensors with digicam-size pixels, and one doesn't want to record all the pixel values when the Airy disk is several pixels across, as it will be for the narrow apertures one needs for some applications such as macro or landscapes. Canon seem to be offering a more flexible sRAW format (a choice of 1/2 or 1/4 the number of pixels) so that one can dump the superfluous resolution at those apertures and at the same time mitigate some of the shortcomings of the Bayer array sensor. And when the optics justifies it, the extra resolution is there if one wants it.
(http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/Aperture%20comparison.jpg)
I bet you can tell which side was f/11 and which side was f/16.
[a href=\"index.php?act=findpost&pid=217508\"][{POST_SNAPBACK}][/a]
OK, I'll bite. It looks to me like the image on the right has lower microcontrast (lower MTF) and so should be the f16 image.
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There is no such thing. The sensors' output is strictly linear (disturbed somewhat by the noise).
Bernard is actually correct. The sensor does exhibit non linearities, especially at the extremes of its response curve, though in practice the output is clipped so that only the most linear part of the sensors response curve is used. This allows uniformity and linearity to be managed and is why when analysing the RAW output data you are seeing a linear response. Typically the non-linearity is less than 2%, but it is still non linear.
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Bernard is actually correct. The sensor does exhibit non linearities, especially at the extremes of its response curve, though in practice the output is clipped so that only the most linear part of the sensors response curve is used
If this were so, then Bernard could not have observed what he thinks he had observed, could he?
However, I doubt that this is correct in the current context. Here I have to admit, that my doubting is based exclusively on observation, not on the knowledge of the technical aspects of sensors.
The issue is, I think, that we are talking about two kinds of linearities.
One is the response of any given sensel. This is IMO linear, excluding the effect of noise. Of course, if the response is non-linear but it is clipped back to the linear segment, then my observation is worthless.
The other issue is the response of the entire sensor. As I explained above, this can be seen as non-linear in the sense, that different pixels (usually grouped in rows or columns) have different saturation points. This can in fact make 0.5%-1% of the entire range.
I can not explain why, but the greens usually have a lower saturation point than the reds and blues, and often there is a gap between the saturation points of pixels in the two green positions; again, it is demonstrated in the documentation I linked above.
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For landscape photography the increased MP will be useless.
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=217312\")
If the increase from 10MP to 15MP in EF-S were useless for landscape photography, then 15MP or more would be equally useless in larger formats too: try telling that to landscape photographers who are happily using the 1DSMkII or 1DsMkIII or even higher pixel counts in medium format.
The possible trade-offs bertween out-of-focus (OOF) effects and diffraction effects is the same in any format: it is just that with the same field of view (FOV), the same combination of OOF effects and diffraction blurring comes at a different f-stop. In fact, the "equivalent" f-stop is different in proportion to the format size and focal length used, so the same [a href=\"http://en.wikipedia.org/wiki/F-number]effective aperture diameter[/url] or entrance pupil diameter (http://en.wikipedia.org/wiki/Entrance_pupil) (focal length divided by aperture ratio.)
So what you say about f/11 in EF-S is about equally true for f/18 in 35mm in a comparison between the 11MP 1Ds and the 16MP 1DsMkII.
Note that f/11 in EF-S gives as much DOF as about f/18 in 35mm (comparing with focal lengths giving the same field of view), so in each case one can often reduce diffraction effects by going to lower f-stops while still get adequate DOF for many landscapes.
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One begins to see where Canon is headed with the 50D. Eventually, it seems likely they are going to offer APS-C or larger sensors with digicam-size pixels, and one doesn't want to record all the pixel values when the Airy disk is several pixels across ... Canon seem to be offering a more flexible sRAW format (a choice of 1/2 or 1/4 the number of pixels) ...
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Maybe so, and with the evidence you have shown us that most of the noise in CMOS sensors arises "downstream" of the photosites, and so hopefully after the "binning" to sRAW modes, such binned output could indeed have noise levels, dynamic range and resolution very close to what is possible from a sensor with fewer, bigger photosites. If so, a win-win for choices between higher resolution and lower noise.
A possible hint of this intention is the prototype sensor that Canon has described in a published paper, with 50 million pixels of 3.5 micron width in a "1D" sized sensor. (It also has ISO gain applied very early, at read-out from photosites to sense capacitors on each column, enhancing options for reducing the effect of downstream noise sources.)
The choice of 1D size is probably because this is the biggest that Canon (or anyone?) can make without stitching, allowing Canon to claim in that paper a record for maximum pixel count on a sensor made without stitching. I doubt that we will ever see that particular sensor in a product, but it is slightly more likely that Canon could offer roughly 3.5 micron pixels in an EF-S sensor, giving about 28MP, with higher ISO lower res. sRAW options like 14MP and 7MP. (And perhaps with no AA filter and very little moiré!)
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http://www.cambridgeincolour.com/tutorials...photography.htm (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm)
Read and learn, and then you can do what Thom Hogan and others (including myself) have done, and do comparisons between various pixel pitch DSLRs at various apertures and see for yourself.
(http://photos.imageevent.com/tonybeach/mypicturesfolder/sharing/websize/DSC_4605_1%20copy.jpg)
As you can see, a 12 MP DSLR was reduced to no better than a 6 MP DSLR at f/16; I'm not sure why the 12 MP DSLR pulls ahead at f/22 (probably a smoother shutter), but since they both look like crap I hardly care.
As recently as today, Thom Hogan has posted at DPR on this very topic: http://forums.dpreview.com/forums/read.asp...essage=29080207 (http://forums.dpreview.com/forums/read.asp?forum=1000&message=29080207)
You must have done direct comparisons to make such a bold statement. Why do I think you are blowing smoke?
The issue will be at f/11, and I will bet you that at f/8 you will see an improvement but at f/11 the 40D will pull even with the 50D because the 50D will have become diffraction limited at f/8.
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Nope nope, diffraction is not effected by MP...it's about the pitch of the micro lenses.
And you're wrong about MP not mattering for landscape and maybe if I put it a different way, you'll get it:
I'd rather cut my frame into 15 million pieces then 10 million pieces.
See what I mean?
Better yet, I'd rather cut my frame into 21 million pieces.
Better enlargements, better crops...diffraction is about micro lens pitch, and not MP per se.
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Nope nope, diffraction is not effected by MP...it's about the pitch of the micro lenses.
And you're wrong about MP not mattering for landscape...[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=217697\")
Micro lenses can tighten or widen the gaps between the photosites, but ironically tightening those gaps will increase (very slightly) the effect of diffraction.
I didn't say more resolution (megapixels) doesn't improve landscape photography. However, if more resolution comes at the cost of lowering the "diffraction effect threshold", then you will have to find a way around that limitation, and probably the best solution will be tilt lenses (and shift for good measure).
Now I'm fully aware of BJL's point about the same issue effecting different formats equally -- indeed, I would go so far as to say that the diffraction limits relative to DOF happen at very nearly the same MPs, so 12 MP is 12 MP regardless of format (just go back to [a href=\"http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm]here[/url] and compare the 5D at f/16 to the D2x at f/11 and you will see what I mean). For me this leads to a simple conclusion, I will get more from purchasing tilt/shift lenses and would gain not much more than larger file sizes by purchasing a higher MP DSLR absent those tilt shift lenses -- YMMV depending on how you approach a scene (if there is nothing close that pushes the DOF, then you are golden).
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These threads are always so hilarious - new camera comes out, pontification begins, hot air is exhaled, and then the same friggen arguments ensue about image quality again and again and again.
I look forward with a smile to see these because I always get a laugh, so thank you all for arguing about absolutely meaningless nonsense
*steve
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thank you all for arguing about absolutely meaningless nonsense [a href=\"index.php?act=findpost&pid=217718\"][{POST_SNAPBACK}][/a]
You're welcome. Thank you for your equally meaningless contribution.
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I look forward with a smile to see these because I always get a laugh, so thank you all for arguing about absolutely meaningless nonsense
I look forward with a laugh to see the digitally challanged to whine about posts they don't understand a word of.
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coming from a 12 mp Nikon d2x and now using the Nikon 12mp Nikon D3 the quality of my photographs have been much improved. It had a lot to do with lens quality more than with the body.
I work a lot with extreme wide angle.
The improvement is that now I have good lenses at last that are sharp corner to corner at d8 ( 14-24mm nikkor 2,8)
In the Dx format there was nothing to buy in this class. The Nikkor 12-24mm d4 was just as bad as the sigma & other offerings- Carl zeiss only came up with a very good 25mm lens. ( Only now they have the 18mm)
I don't know how the Canpn wide angles are but to address the 15mp i guess you need the 2200$ 14mm 2,8 lens
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I agree with Semillarimages. Post 81.
There is a lot of good technical information in this thread, but the bashing is tiresome.
I want to get excited for new cameras, not argue interpretations, physics, semantics, and egos.
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I have a 30D I've been using for three years now. I'm planning on upgrading to the 5d mk II and hoping that it's a great camera.
If it has the same pixel pitch as the 50D, how many megapixels would it be?
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I also grow weary of endless speculation about a camera that we haven't yet seen. I don't consider myself a pixel-peeper, but I have been known to test my lenses at multiple apertures and focal lengths to find the sweet spot. I have read this discussion from beginning to end. I have learned more about diffraction than I knew before. BUT...
There are a three main areas that I think this discussion cavalierly misses.
One: All of these discussions are predicated on extrapolating theoretical limits based upon the previous generations of technology. We should not assume that this sensor and the camera that goes around it will be limited by all the same factors that the previous generation was. Unless you can independently test a lens without a sensor, or film, then we must wait to see how it performs on the new sensor. This is a classic mistake of scientists....changing too many variables and then trying to make conclusions based upon assumptions and theories.
This leads me to the second area.
Two: Unknown properties of sensor. This new sensor can easily have different thermal or electrical properties that would decrease the effect of noise. When silicon technology advances to a new process node (I don't even know if they have moved to a new node) typically, the gates and circuits become smaller. This means that it takes less voltage to power the device (unless they have increased the processor speed too, as is general the case with CPUs). With a decrease in voltage and power, there is a proportional decrease in temperature and noise. I am not saying this is the case with the 50D. What I am saying is that there is a great deal that can be done on chip to change the game--change the performance of the sensor.
This leads me to my final point.
Three: In-camera digital processing. With improved DIGIC processors (more processing power) the images can have more substantial filters and can be processed more quickly. I know I am not alone when I relate my first experience of digital image enhancement, when I moved that levels slider bar and suddenly saw details in the shadows that I never knew were there. Detail that was not originally visible suddenly appeared--as if by magic. Similarly, In-camera digital processing could squeeze out a bit more resolution than we previously thought possible. In camera sharpening algorithms that could account for predictable diffraction effects could easily be imagined. Further, Canon, with their detailed knowledge of the sensor's attributes, should be able to create highly effective processing algorithms.
So, this is why I will wait for the camera before I declare it a non-starter that is diffraction limited beyond f/8 (I love f/8, it is my favorite aperture). When the camera comes out, I will closely study the sample photos, and I might even look at some MTF charts.
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So, this is why I will wait for the camera before I declare it a non-starter that is diffraction limited beyond f/8 (I love f/8, it is my favorite aperture). When the camera comes out, I will closely study the sample photos, and I might even look at some MTF charts.
[a href=\"index.php?act=findpost&pid=217869\"][{POST_SNAPBACK}][/a]
I think my point is repeatedly missed. It's not that the 50D becomes worse than the 40d or 30D beyond f/8, my point is that its resolution advantages quickly diminish to indistinguishable and all you have are bigger files. It is not my intention to rain on anyone's parade and it was merely a point I raised in passing that has been repeatedly challenged and now is condemned as "bashing". If someone thinks they can buy this new camera and by virtue of its 15 MP resolution set their lens to f/16 and get better images than they were getting from their 30D, well they will be disappointed.
Frankly, I'm unimpressed with discussions about the putative image quality (both pro and con) of a camera no one here has yet handled -- and I find most sample photos dubious (especially those claiming to demonstrate a camera's weaknesses), there are a lot of photographers who are too quick to blame their gear rather than their technical shortcomings.
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Tony, Canon may have pushed the envelope by making smaller photosites and the gapless microlens, and all we can do is wait for real results. If having more mega pixels on the same size sensor alone only produces more defraction, then such results will prove to be a nonsense marketing gimmick, and make me a happier 40D owner.
I can tell you in the studio when I'm pushing my 40D to the limit, that I have run into the defraction wall at F18 (where it gets noticed), that was easily fixed by placing the same lens onto my old 1Ds (mark 1), with full frame sensor and larger sites.
So, I think a 5d mk ii (if and when it's announced) would still of interest to me over a 50d, and this speculation is just too hard to avoid in months ahead that we have to wait.
This site, if not mentioned before, might be of interest:
http://diglloyd.com/diglloyd/free/Diffraction/index.html (http://diglloyd.com/diglloyd/free/Diffraction/index.html)
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15MP on an APS-C sensor? Isn't that overkill? Didn't Canon learn their lesson with the 1DSMK3?
My guess is as long as the manufacturers can convince the lemmings they need more megapixels, they'll continue down this silly path, while real improvements will trickle in slowly.
Don't forget about us landscape photographers. We always need as many mp as we can get. Not that I'm implying the 50D is the ultimate landscape lens. However others in the line have and will have more mp and this is not unwelcome for landscape shooting. It's also good for wildlife shooting when one has to crop a tiny subject out of a large picture and we want to maintain enough resolution to make a decent print.
I am not one who wants to invest in a MF system to get those high-end results due to the size and weight of those systems and the cost. The closer 35mm gets to those resolutions the happier I am. I'm sure portrait and wedding photographers don't care because they have the resolution they need already. Just remember that there are plenty of segments of photography where higher resolution is welcome.
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For landscape photography the increased MP will be useless. Stop down to f/11 and compare a 50D file to a 40D file; in terms of resolution there will be no difference.
[a href=\"index.php?act=findpost&pid=217312\"][{POST_SNAPBACK}][/a]
Oh, you have a 50D then? C'mon, the f/stop only increases the DOF, it's not going to put more pixels in the image. The 50D file will be bigger and have finer detail.
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Oh, you have a 50D then? C'mon, the f/stop only increases the DOF, it's not going to put more pixels in the image. The 50D file will be bigger and have finer detail.
[a href=\"index.php?act=findpost&pid=217919\"][{POST_SNAPBACK}][/a]
You should go back and read the long thread. Tony's point is well explained and possibly accurate for the 50D.
What is left to be determined is whether canon's 50D has made some innovation that compensates for diffraction.
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I think my point is repeatedly missed. It's not that the 50D becomes worse than the 40d or 30D beyond f/8, my point is that its resolution advantages quickly diminish to indistinguishable and all you have are bigger files.
[a href=\"index.php?act=findpost&pid=217880\"][{POST_SNAPBACK}][/a]
Perhaps the end game with a 50Mpixel sensor with lenses/apertures that cannot resolve more than a 12Mpixel sensor is to increase the range of pixel colours that are used to detect the image to increase colour gamut. So, instead of RGB we could get CMYK or RGB plus Yellow and Magenta pixels. There is no rule that the sensor should remain a Beyer RGB pattern with 2 Green 1 Red 1 Blue in a square grid. There may be other reasons to move from traditional layouts, e.g. variable size pixels (large/ small) to provide greater dynamic range or specific layouts to facilitate pixel binning.
Even if the spatial resolution is limited by the lens there may be good reason to use the new techniques in innovative ways to drive other enhancements in overall performance.
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You should go back and read the long thread. Tony's point is well explained and possibly accurate for the 50D.
What is left to be determined is whether canon's 50D has made some innovation that compensates for diffraction.
[a href=\"index.php?act=findpost&pid=217921\"][{POST_SNAPBACK}][/a]
I did and I'm not fully convinced that diffraction is going to be as big a issue as postulated. The fact is that the camera isn't out yet and no one really knows how those gapless microlenses are going to affect diffraction one way or the other - well, the Canon engineers almost certainly know, but they aren't talking about it. We are all also aware that different lenses have different diffraction characteristics. If Tony turns out to be right then T/S lenses are always there of course to save us from diffraction on product shots and landscape shots, as an aside we could use some more those T/S lenses. I confess that I'm not going to buy the 50D for landscape work myself because I am aware that diffraction does come quicker on APS-C. I'll be getting the new FF for those shots.
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I did and I'm not fully convinced that diffraction is going to be as big a issue as postulated. The fact is that the camera isn't out yet and no one really knows how those gapless microlenses are going to affect diffraction one way or the other - well, the Canon engineers almost certainly know, but they aren't talking about it.
[a href=\"index.php?act=findpost&pid=217928\"][{POST_SNAPBACK}][/a]
Gaples microlenses will help improve light collecting ability of the pixels, but diffraction is determined mainly by the pixel spacing, which is not affected by the gapless lenses.
We are all also aware that different lenses have different diffraction characteristics. If Tony turns out to be right then T/S lenses are always there of course to save us from diffraction on product shots and landscape shots, as an aside we could use some more those T/S lenses.
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Theoretically, diffraction is determined solely by the aperture (f/stop). The type of lens should have little to do with diffraction as long as the f/stop is the same. We often read in lens reviews that a particular lens performs well down to a certain aperture, but beyond that diffraction sets in quickly and performance falls off. That should be true for any lens, but perhaps there are some differences that I am not aware of.
I confess that I'm not going to buy the 50D for landscape work myself because I am aware that diffraction does come quicker on APS-C. I'll be getting the new FF for those shots.
[a href=\"index.php?act=findpost&pid=217928\"][{POST_SNAPBACK}][/a]
Diffraction does come quicker on APS-C, but this is partially offset by less need to stop down for equivalent depth of field. Even though the 50D becomes diffraction limited at a larger aperture than a 10 MP APS camera, the image quality at f/16 will be no worse with the 50D than the 40D. If you have a good lens and can use a larger aperture, you have the option of getting better IQ with the 50D. Lenses with tilts and shifts can help with depth of field as you point out, and you can also use image stacking to improve depth of field.
If you want to use panorama techniques for landscape work, say combining three or four shots in portrait mode to make a final picture in landscape format, you can get very high resolution pictures. Some photographers prefer APS cameras for this purpose since you are using the central portion of the image with the best quality. If you need 4 by 5 quality, you can use multirow techniques.
I have the Nikon D3, which trades resolution for light gathering ability (the opposite approach to the 50D), but there trade offs and which approach is best depends on your needs. Digital workflow is very flexible, and one can often work around many of the limitations of one's camera. The D3 is good for sports and photojournalism, but the 1Ds3 would be better for landscape.
Bill
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Discussions like these serve the purpose of raising awareness of the issues involved. I'm surprised that anyone should object to them.
On the other hand, perhaps I can understand why, when one poster (whom I shall not name), after objecting to the discussion, goes on to ask how many pixels would a full frame sensor have if its pixel pitch were that of the 50D, thus demonstrating that he is either mathematically challenged, or is unaware of the size difference between the Canon cropped format and FF 35mm.
I get the impression from some of the posts in this thread that some posters believe there is a connection between pixel pitch and diffraction and that high density sensors are somehow causing diffraction.
Perhaps it's just the way they are expressing themselves, so let's be clear about this. Diffraction is a property of the lens, not of the sensor. Don't blame the sensor for the limitations of the laws of physics with regard to optics.
The P45 has approximately the same pixel pitch as a 20D. Because the sensor is double the size of 35mm, one needs to stop down about one stop more than one would with a 35mm system to get the same DoF as FF 35mm, and 2 1/2 stops more to get the same DoF as the 50D. You don't hear P45 owners whingeing about their small pixel pitch, do you?
Be grateful for what's being offered. There is already a lot of research taking place in nanotechnology with regard to the production of artificial materials with a negative refractive index. If it ever becomes possible to use such materials in camera lenses, you might be able to record sharp images at F32 with a future 50mp APS-C sensor .
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The P45 has approximately the same pixel pitch as a 20D. Because the sensor is double the size of 35mm, one needs to stop down about one stop more than one would with a 35mm system to get the same DoF as FF 35mm, and 2 1/2 stops more to get the same DoF as the 50D
It is still a nonsense.
The depth of field has NOTHING to do with the sensor size. It's a simple thing (how did you express this? except for the mathematically challenged?).
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It is still a nonsense.
The depth of field has NOTHING to do with the sensor size. It's a simple thing (how did you express this? except for the mathematically challenged?).
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Once again, Gabor, you have forgotten that my concern is with the woods. Your concern appears to be only with the trees within the woods.
Without regard to such factors as composition and FoV, you are perfectly correct that DoF has nothing to do with sensor size. But my compositions and images have a lot to do with sensor size. The sensor size influences my choice of focal length and the perspective from which I take the shot, and that in turn influences DoF.
I'm surprised you find such ideas nonsense. It's pretty basic to me. I'm dealing with such issues all the time.
Edit: For the sake of clarity, I should elaborate on what is probably a source of much confusion. I have assumed in my comments that most users of DSLRs wish to maximise the real estate of their sensors. The people contributing to this thread are obviously concerned about resolution. If you are concerned about resolution, you don't use a 50mm lens and then crop the resulting image to the same field-of-view you would have got using an 80mm lens from the same position. You try to use an 80mm lens, even if it's a zoom of lower quality than the 50mm prime.
If two photographers are standing next to each other, one with a 20D and 50mm lens, and the other with a 1Ds3 and 50mm lens, and they shoot the same scene using the same F stop, then the parts that both images have in common, will, of course, be very similar in terms of both resolution and DoF, but the compositions will be very different.
Most photographers carry a range of lenses or a zoom with a range of focal lengths. People who claim that DoF has nothing to do with sensor size are being very disingenuous.
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I get the impression from some of the posts in this thread that some posters believe there is a connection between pixel pitch and diffraction and that high density sensors are somehow causing diffraction.
Perhaps it's just the way they are expressing themselves, so let's be clear about this. Diffraction is a property of the lens, not of the sensor. Don't blame the sensor for the limitations of the laws of physics with regard to optics.[a href=\"index.php?act=findpost&pid=217977\"][{POST_SNAPBACK}][/a]
I resemble that remark. I know I'm beating a dead horse here, but feel compelled to keep it up because some think the horse is merely sleeping. The point isn't that the photosites are "causing" the diffraction, it's that that the close proximity of the photosites to one another is recording the diffraction; and the closer together they are the sooner they record that diffraction.
Did you read and fully comprehend the article I have already twice linked to in this thread? Have you performed any tests to prove or disprove what I'm asserting? I'm shocked, shocked that no one here doesn't have a couple of cameras (say a D300 and a D700), a good lens, a resolution target, a solid tripod and remote shutter release, and the patience and curiosity to test this theory for themselves and then present their results.
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Diffraction is a property of the lens, not of the sensor
That's right. However, the diffraction effect is a function of the diffraction and of the circle of confusion, which depends on the pixel size.
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I resemble that remark. I know I'm beating a dead horse here, but feel compelled to keep it up because some think the horse is merely sleeping. The point isn't that the photosites are "causing" the diffraction, it's that that the close proximity of the photosites to one another is recording the diffraction; and the closer together they are the sooner they record that diffraction.
Did you read and fully comprehend the article I have already twice linked to in this thread? Have you performed any tests to prove or disprove what I'm asserting? I'm shocked, shocked that no one here doesn't have a couple of cameras (say a D300 and a D700), a good lens, a resolution target, a solid tripod and remote shutter release, and the patience and curiosity to test this theory for themselves and then present their results.
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=218007\")
First, why is a problem if the sensor is recording diffraction? When the sensor is not recording diffraction, then the limiting factor in resolution is the pixel pitch of the sensor, and that means that resolution offered by the lens is being left on the table by the shortcomings of the sensor. At least one can be assured that if the sensor is showing diffractions effects, that it is not a source of lost detail in the image. A coarser pixel pitch never provides more resolution, it simply throws away resolution in a wider variety of circumstances where a finer pixel pitch could deliver it.
Second, while I myself have not performed tests, I have analyzed those performed by DPReview, which has tested the Nikon and Canon 70-200/2.8 on both FF (D3 and 5D respectively) as well as APS-C (D300 and 40D respectively). I reported on that analysis in a variety of fora:
[a href=\"http://forums.dpreview.com/forums/read.asp?forum=1021&message=28590555]http://forums.dpreview.com/forums/read.asp...essage=28590555[/url]
http://www.naturescapes.net/phpBB3/viewtop...397195#p1397195 (http://www.naturescapes.net/phpBB3/viewtopic.php?f=2&t=137683&p=1397195#p1397195)
The bottom line is that smaller pixels provide more resolution in both of these examples, even when the optics is diffraction limited. Now granted, this resolution is based on slanted edge tests and may not always be realized in practice as actual line pair resolution in the diffraction limited regime; but certainly the finer pixel pitch sensor will never do worse than the coarser one under any circumstance.
The obsession with diffraction effects at small apertures ignores the substantial resolution benefit to be gained when shooting at wider apertures with a finer pixel pitch. A finer pixel pitch does no worse at small apertures, and substantially better at wide apertures. And so all the moaning about "diffraction limitation" of finer pixel pitch seems to me misplaced.
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I will tend to agree with ejmartin. This is how I understand it.
1. Diffraction is a property of the lens aperture
2. The point where a lens becomes diffraction limited is the point where other optical aberrations do not mask the diffraction effect. Thus a perfect lens is diffraction limited at its widest aperture. No amount of closing down will increase its resolution.
3. Diffraction being a property of the lens (and independent of the kind of lens) will interact with pixel pitch according to the circle of confusion theory.
4. Because of 3. at some point while closing the aperture (thus increasing diffraction) the effect is going to be recorded by the sensor (depending on the pixel pitch). The smaller the pitch the earlier will diffraction effects be recorded (be noticable). From this and 1. above we can deduce that given a recording medium with infinite resolution, total system resolution will start to drop as soon as the perfect lens will be stopped down even a little.
5. 4 above does not mean that system resolution of the a lens x a smaller pitch sensor vs the same lens x a larger pitch sensor will be equalized when diffraction starts being noticeable for the smaller pitch sensor. Nothing in 4. leads us to believe this.
Saying that diffraction is higher with smaller pitched sensors is not only theoretically incorrect it is also misleading. It is just that diffraction starts being noticeable earlier limiting a HIGHER system resolution to start with. Diffraction at that point is not noticeable with the larger pitch sensor because the system resolution is LOWER anyways thus it is not limited by diffraction at that point.
If one uses a lens diffraction limited at its widest aperture and a theoretical sensor with pixel pitch small enough to record diffraction effects at that aperture, it is reasonable to expect that ANY amount of closing down the lens will lower the system resolution. This does not mean in any way that this lower system resolution will not be higher than using the same lens with a smaller resolution sensor at that aperture.
So, for me, increased sensor resolution is ALWAYS a good thing from a system resolution point of view. It is just that to get the max out of it one will need better and better lenses. There is no such thing as too small a pixel pitch until we reach the limits of lens design where more will provide no advantage. Of course ignoring other issues like noise etc.
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On the other hand, perhaps I can understand why, when one poster (whom I shall not name), after objecting to the discussion, goes on to ask how many pixels would a full frame sensor have if its pixel pitch were that of the 50D, thus demonstrating that he is either mathematically challenged, or is unaware of the size difference between the Canon cropped format and FF 35mm.
[a href=\"index.php?act=findpost&pid=217977\"][{POST_SNAPBACK}][/a]
Thanks Ray, I know who I am. I am mathematically challenged, I did not feel like taking the time to perform the calculations only to pull my hair out. I wondered if someone had already done them before me. Of the 1.6x crop factor I've been using the last three years I am most certainly aware.
I does look like I was on the wrong path though.
30D - 6.4 micron pixel pitch
50D - 4.7
5D - 8.2
1ds Mk III - 6.4 (Same as the 30D...this I didn't know)
So if, as I pondered, the 5D Mk II had the same 4.7 micron pixel pitch of the 50D, it would have a fair bit more resolution than the 1Ds 3, something that is certainly not going to happen.
What are people's estimates for 5D Mk II megapixels? It has to be higher, at least in my opinion, than the 50D's 15.1 and lower than the 1Ds Mk 3's 21.1.
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Thanks Ray, I know who I am. I am mathematically challenged, I did not feel like taking the time to perform the calculations only to pull my hair out. I wondered if someone had already done them before me. Of the 1.6x crop factor I've been using the last three years I am most certainly aware.
I does look like I was on the wrong path though.
30D - 6.4 micron pixel pitch
50D - 4.7
5D - 8.2
1ds Mk III - 6.4 (Same as the 30D...this I didn't know)
So if, as I pondered, the 5D Mk II had the same 4.7 micron pixel pitch of the 50D, it would have a fair bit more resolution than the 1Ds 3, something that is certainly not going to happen.
What are people's estimates for 5D Mk II megapixels? It has to be higher, at least in my opinion, than the 50D's 15.1 and lower than the 1Ds Mk 3's 21.1.
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Well, I'm glad you have not taken offense . A full frame sensor is approximately 2.6x the area of the Canon cropped format, so a full frame sensor comprised of 50D pixels would have 15.4 x 2.6 = 40mp.
Considering that at least one company will be announcing a 24mp FF DSLR within the next month or so, 40mp does not seem too far away. A year or two maybe?
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All this information is making me defraction limited.
Very good stuff here, makes me want to test the 50D even more.
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The depth of field has NOTHING to do with the sensor size
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DOF and OOF effects are however deeply related to the size of the image that you form on the sensor.
If you photograph the same subject from the same distance and want an image on the sensor of twice the (linear) size in order to make full use of a larger sensor, then you need to use twice the focal length, and then with the same aperture ratio, the circles of confusion at each point of the image will have _four_ times the diameter.
Thus when you present the same sized image of the subject on the print or on-screen, so using half the degree of enlargement, the COC at each OOF point on the print will have twice the diameter. That is half the DOF and stronger OOF blurring by any measure.
Alternatively, if you use the same effective aperture diameter (entrance pupil diameter) and thus twice the aperture ratio with that doubled focal length and image size, each COC has twice the diameter, and by the way each diffraction spot has twice the Airy disc diameter.
Thus when you display at equal image size, all COC's and diffraction spots on the displayed image are of equal size: exactly the same DOF, OOF blurring and diffraction blurring.
Thus 15MP in any format is equally useful for landscape photography so long as diffraction control does not force you to use f-stops so low that lens aberrations impair image quality. You just have to choose a different f-stop (same effective aperture diameter) to get a given combination of OOF and diffraction effects when filling a different frame size with the desired image.
With good SLR lenses giving best resolution at f/5.6 or even f/4 or below, diffraction/aberration trade-offs still allow resolution well beyond what any curent DLSR pixel size offers. Three micron pixel spacing might start pushing the limits of the highest resolving SLR lenses, but that would be 25MP in 4/3, 37MP in EF-S, etc.
P. S. NikonsR summarizes my point very nicely in a different way, particularly in his final paragraph.
Diffraction like lens aberrations lead only to a case of the law of diminishing returns for the increases in overall resolution given by increasing sensor resolution; never a loss, and so far we are not at the point beyond which there is no significant improvement with further sensor resolution increase, so long as good lenses are used.
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I will tend to agree with ejmartin. This is how I understand it.
So, for me, increased sensor resolution is ALWAYS a good thing from a system resolution point of view. It is just that to get the max out of it one will need better and better lenses. There is no such thing as too small a pixel pitch until we reach the limits of lens design where more will provide no advantage. Of course ignoring other issues like noise etc.
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The posts by ejmartin and NikosR clear up much of the confusion about small pixel pitch. Nikos is ignoring noise, but in the real world noise is a major limiting factor and there is much confusion concerning pixel size noise and signal to noise. On a per pixel basis if other factors are held constant, the large pixel will have a better S:N expressed as a standard deviation. However, we look at the entire image, not individual pixels. If the sensor size is held constant along with other factors and the pixel count is increased, the standard deviation of the noise will increase but the noise will be finer grained and less obvious. If one downsizes the higher resolution image to the same size as the lower resolution image, the noise will be reduced by pixel [a href=\"http://www.photomet.com/pm_solutions/library_encyclopedia/index.php]binning[/url].
EJ Martin (http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/index.html) gives an excellent analysis. He concludes that the sensor size, not the pixel size, is the critical factor here.
If you resample your D50 image in Photoshop to a smaller file size, the effects of shot noise will be reduced, but the effects on read noise will not be as good as if the binning were done in hardware as the above link points out. For example in 2x2 hardware binning, the superpixel is read with the same read noise as the individual pixels. In the case of the D50 image downsized by half, there are four read noises that add in quadrature, and the read noise would be decreased by 50% and not by 75% as with hardware binning.
Of course, with the d50, other things are not held constant and Canon has presumably improved the sensor over that of the D40. It will be interesting to examine actual photos taken with both cameras, and I would imagine that the noise for photos printed at the same lateral dimension (e.g. 16 by 20 inch) will not be that different between the two cameras.
However, one main reason for increased megapixels to print at a larger size, and the larger print would bring out the noise. A 15 MP full frame sensor would have an advantage here.
Bill
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If you photograph the same subject from the same distance and want an image on the sensor of twice the (linear) size in order to make full use of a larger sensor, then you need to use twice the focal length, and then with the same aperture ratio, the circles of confusion at each point of the image will have _four_ times the diameter
1. The effect of diffraction is the airy disk; the circle of confusion is the limitation of the airy disk to avoid visible effect of the diffraction. Thus one has to calculate the airy disk diameter.
2. The diameter of the airy disk is directly proportional to the focal length, and inversely proportional to the aperture diameter. Thus it is a linear function of the quotient of focal length and aperture diameter, in other words it is a linear function of the aperture number.
When the aperture number is kept unchanged, the diffraction too (the airy disk diameter) remains unchanged, independently of the focal length.
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The diameter of the airy disk is directly proportional to the focal length, and inversely proportional to the aperture diameter. Thus it is a linear function of the quotient of focal length and aperture diameter, in other words it is a linear function of the aperture number.
When the aperture number is kept unchanged, the diffraction too (the airy disk diameter) remains unchanged, independently of the focal length.
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No disagreement there, Gabor. What surprises me is that you seem to have ignored the relationship between the size of the Airy disc and the size of the composition or image. The effect of the absolute size of the Airy disc is pretty meaningless outside the context of a specific size of image.
The Airy disc produced by a 50mm lens at F11 is the same whether that lens is attached to a 35mm camera or a P&S camera, but you would never use F11 with a P&S camera if you wanted a sharp image. In fact, I suspect that most P&S cameras do not offer the option of F11, just as most 35mm lenses do not offer the option of F45.
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No disagreement there, Gabor. What surprises me is that you seem to have ignored the relationship between the size of the Airy disc and the size of the composition or image. The effect of the absolute size of the Airy disc is pretty meaningless outside the context of a specific size of image.
The Airy disc produced by a 50mm lens at F11 is the same whether that lens is attached to a 35mm camera or a P&S camera, but you would never use F11 with a P&S camera if you wanted a sharp image. In fact, I suspect that most P&S cameras do not offer the option of F11, just as most 35mm lenses do not offer the option of F45.
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True. But you can't use a 50mm on a P&S either....
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I will tend to agree with ejmartin. This is how I understand it.
1. Diffraction is a property of the lens aperture
2. The point where a lens becomes diffraction limited is the point where other optical aberrations do not mask the diffraction effect. Thus a perfect lens is diffraction limited at its widest aperture. No amount of closing down will increase its resolution.
3. Diffraction being a property of the lens (and independent of the kind of lens) will interact with pixel pitch according to the circle of confusion theory.
4. Because of 3. at some point while closing the aperture (thus increasing diffraction) the effect is going to be recorded by the sensor (depending on the pixel pitch). The smaller the pitch the earlier will diffraction effects be recorded (be noticable). From this and 1. above we can deduce that given a recording medium with infinite resolution, total system resolution will start to drop as soon as the perfect lens will be stopped down even a little.
5. 4 above does not mean that system resolution of the a lens x a smaller pitch sensor vs the same lens x a larger pitch sensor will be equalized when diffraction starts being noticeable for the smaller pitch sensor. Nothing in 4. leads us to believe this.
Saying that diffraction is higher with smaller pitched sensors is not only theoretically incorrect it is also misleading. It is just that diffraction starts being noticeable earlier limiting a HIGHER system resolution to start with. Diffraction at that point is not noticeable with the larger pitch sensor because the system resolution is LOWER anyways thus it is not limited by diffraction at that point.
If one uses a lens diffraction limited at its widest aperture and a theoretical sensor with pixel pitch small enough to record diffraction effects at that aperture, it is reasonable to expect that ANY amount of closing down the lens will lower the system resolution. This does not mean in any way that this lower system resolution will not be higher than using the same lens with a smaller resolution sensor at that aperture.
So, for me, increased sensor resolution is ALWAYS a good thing from a system resolution point of view. It is just that to get the max out of it one will need better and better lenses. There is no such thing as too small a pixel pitch until we reach the limits of lens design where more will provide no advantage. Of course ignoring other issues like noise etc.
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A minor quibble - diffraction is a property of light, not the lens. A good lens handles it well.
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A minor quibble - diffraction is a property of light, not the lens. A good lens handles it well.
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Well, it's a property of light interacting with the aperture Not sure that lens quality makes a difference though.
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A minor quibble - diffraction is a property of light, not the lens. A good lens handles it well.
Diffraction is the property of light, occuring when it passes the edge of an object. I wonder if there are photographic lenses without any edge; even at fully open aperture, if nothing else then the barrel causes diffraction. Perhaps fisheyes?
Is there any lens, which can "handle" this?
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Diffraction is the property of light, occuring when it passes the edge of an object. I wonder if there are photographic lenses without any edge; even at fully open aperture, if nothing else then the barrel causes diffraction.
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Diffraction is not simply sourced by light passing near the edge of an obstruction (eg aperture blades); rather it arises from interference effects of light passing through the entire aperture. All portions of the aperture opening contribute equally, and so one cannot localize its source any more finely than to say it comes from the aperture (and not just the edge of the aperture opening).
And so, any lens has a finite aperture and thus exhibits diffraction, more and more the smaller the aperture is closed down. Ultimately, the effects of diffraction are dependent only on the f-number and not any particular design of the aperture, lens barrel, etc.
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1. The effect of diffraction is the airy disk; the circle of confusion is the limitation of the airy disk to avoid visible effect of the diffraction. Thus one has to calculate the airy disk diameter.
2. The diameter of the airy disk is directly proportional to the focal length, and inversely proportional to the aperture diameter. Thus it is a linear function of the quotient of focal length and aperture diameter, in other words it is a linear function of the aperture number.
When the aperture number is kept unchanged, the diffraction too (the airy disk diameter) remains unchanged, independently of the focal length.
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You have misunderstood what I wrote; I was talking about two factors affecting resolution, diffraction and out of focus effects:
1. out of focus effects, as measured by the diameter of the circle of confusion in the focal plane, which is proportional to the square of the focal length and inversely proportional to aperture ratio,
and
2. diffraction effects, measured by the diameter of the Airy disc, which is independent of the focal length and proportional [added word] to the aperture ratio.
Together these mean that if the focal length and aperture ratio are increased by the same factor, the size of the image, teh Airy discs and eh circles of confusion all increase in proportio to the focal length. Thus when enlargement is chosen to give equal iamge size it als gives equal iszed Airy discs and circles of confusion.
If you insist on looking only on what happens at equal aperture ratio, doubling focal length will give equal sized Airy discs (so half the diffraction blurring on equal sized prints) but four times the circle of confusion at each OOF points, so half the DOF on equal sized prints. Since the main reason for having to stop down to "diffraction challenged" apertures is to get adequate DOF, the larger format and focal length will not be able to use the same aperture ratio; it will have to use double the f-stop to get that same desired DOF.
It amazes me that so many people keep making comparisons between formats under the assumption that a smaller format must use an equally high aperture ratio (and/or equally high ISO speed) as a larger format even when discussing situations when there is the option of changing to a lower aperture ratio (allowing a correspondingly less high ISO speed).
P.S. Before anyone says it: in the unusual situation that a high f-stop is chosen to get a long enough exposure at minimum ISO speed rather than for sufficient DOF, neutral density filters will allow a lower f-stop and thus reduced diffraction effects.
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The amount of diffraction relates the size of the opening the light passes through. F/ stops are a variable correlating to the ratio of the focal length of a lens to its (or its diaphragm's) diameter. In other words, a 50mm lens at f/8 has the same amount of diffraction applied to the light as a 100mm lens does at f/11.
drgary
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True. But you can't use a 50mm on a P&S either....
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Well, I,m glad you agree with my point. However, it's not correct that you can't use a 50mm lens on a P&S. There are a number of P&S cameras with 10x or 12x zooms which reach and exceed 50mm in focal length.
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Diffraction is the property of light, occuring when it passes the edge of an object. I wonder if there are photographic lenses without any edge; even at fully open aperture, if nothing else then the barrel causes diffraction. Perhaps fisheyes?
Is there any lens, which can "handle" this?
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Thats true. By handle it well, I mean a lens that yields high resolution close to the full aperture. A basic kit lens may be sharpest at over f9 on a f4.5-5.6 and even then its not very sharp. A good lens might be sharpest at 5.6 and still very sharp at f2.8 on a 2.8
A black hole would be a lens without an edge in the normal sense.
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Thats true. By handle it well, I mean a lens that yields high resolution close to the full aperture. A basic kit lens may be sharpest at over f9 on a f4.5-5.6 and even then its not very sharp. A good lens might be sharpest at 5.6 and still very sharp at f2.8 on a 2.8
A black hole would be a lens without an edge in the normal sense.
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Yes. But as I said above this is not 'handling diffraction well'. It is just that other aberrations are handled well so diffraction is the limiting factor. BTW Diffraction is not caused by the 'edge'. It is caused by the hole.
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The amount of diffraction relates the size of the opening the light passes through. F/ stops are a variable correlating to the ratio of the focal length of a lens to its (or its diaphragm's) diameter. In other words, a 50mm lens at f/8 has the same amount of diffraction applied to the light as a 100mm lens does at f/11.
drgary
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The first part is right but the last bit seems incorrect to me, but I'm no physicist. The physical aperture diameter of a 50mm lens at F8 is given by the simple formula: Focal length/F stop.
50mm/8 = 6.25mm. However, 100mm/11 = 9mm. Diffraction should be less with the 100mm lens at F11.
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The amount of diffraction relates the size of the opening the light passes through. F/ stops are a variable correlating to the ratio of the focal length of a lens to its (or its diaphragm's) diameter. In other words, a 50mm lens at f/8 has the same amount of diffraction applied to the light as a 100mm lens does at f/11.
drgary
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That depends on what you mean by "the same amount of diffraction". The range of angles over which the direction of the light spreads after passing through the aperture depends only on the physical size of the aperture; since aperture is (focal length/f-number), then indeed the range of angles will be the same for 50mm @ f8 and for 100mm @ f11.
However, the relevant quantity for photography is the amount of blur (the Airy disk diameter) at the focal plane; for that, one should multiply the spread in angles by the distance from the aperture to the focal plane. The spread in angles is proportional to 1/aperture, that times the distance gives the spot size at the focal plane proportional to (focal length/aperture)=f-number.
So the relevant quantity for photography (the diffraction spot size) depends only on the f-number and not the aperture or focal length separately. And so that 50mm @f8 will have sqrt[2]~1.4 times less diffraction in the image than the 100mm @ f11.
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sorry, double post.
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That depends on what you mean by "the same amount of diffraction". The range of angles over which the direction of the light spreads after passing through the aperture depends only on the physical size of the aperture; since aperture is (focal length/f-number), then indeed the range of angles will be the same for 50mm @ f8 and for 100mm @ f11.
However, the relevant quantity for photography is the amount of blur (the Airy disk diameter) at the focal plane; for that, one should multiply the spread in angles by the distance from the aperture to the focal plane. The spread in angles is proportional to 1/aperture, that times the distance gives the spot size at the focal plane proportional to (focal length/aperture)=f-number.
So the relevant quantity for photography (the diffraction spot size) depends only on the f-number and not the aperture or focal length separately. And so that 50mm @f8 will have sqrt[2]~1.4 times less diffraction in the image than the 100mm @ f11.
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This is getting a bit confusing, Emil . If we are talking about the same scene, the same composition, the same field of view from the same perspective, then the 100mm lens at F11 will produce less diffraction than the 50mm lens at F8, but of course the sensor with the 100mm lens would have to be bigger.
If we are talking about a fixed size sensor, then the diffraction spot size will vary only with F stop, but the FoV will vary in inversely with the focal length. Is this correct?
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Yes. But as I said above this is not 'handling diffraction well'. It is just that other aberrations are handled well so diffraction is the limiting factor. BTW Diffraction is not caused by the 'edge'. It is caused by the hole.
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Diffraction is the limiting factor in lens design. Making it irrelevant is handling it well.
What about the hole causes it if not the edge? Diffraction happens when light hits an object. Any object. Its very small unless the amount of light getting through is small relative to the amount of diffraction. A small hole has a small area relative the the edges (circumference) where diffraction happens. Thats a result not a cause.
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This is getting a bit confusing, Emil . If we are talking about the same scene, the same composition, the same field of view from the same perspective, then the 100mm lens at F11 will produce less diffraction than the 50mm lens at F8, but of course the sensor with the 100mm lens would have to be bigger.
If we are talking about a fixed size sensor, then the diffraction spot size will vary only with F stop, but the FoV will vary in inversely with the focal length. Is this correct?
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Sorry, I was referring to the physical size of the diffraction spot (Airy disk) on the sensor, at a fixed distance from the subject. The size of that physical spot depends only on the f-number. So for instance, one could "zoom with the feet" and move twice as close with the 50mm compared to the 100mm to get a comparable field of view (ignoring perspective effects), then the diffraction spot size depends only on the f-number.
Alternatively, one can stay in the same place and use two different cameras. For f11 to have the same diffraction spot size relative to frame size as f8 on another camera, the ratio of the sensor sizes would have to be sqrt[2] in linear dimension (f11 would need a larger sensor). For comparable field of view, a 100mm lens must be on a sensor twice larger in linear dimension than a 50mm lens; so 100mm at f11 on FF is equivalent to 50mm @ f5.6 on a half-size sensor (eg 4/3 system) in terms of diffraction effects, or a bit under f8 @ ~66mm on APS-C.
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Diffraction is the limiting factor in lens design. Making it irrelevant is handling it well.
What about the hole causes it if not the edge? Diffraction happens when light hits an object. Any object. Its very small unless the amount of light getting through is small relative to the amount of diffraction. A small hole has a small area relative the the edges (circumference) where diffraction happens. Thats a result not a cause.
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I would have said that optical aberrations are the limiting factor in lens design. Diffraction is a function of f-number, and no change in the lens design is going to alter that.
From your choice of wording, I suspect that the mental construct you have in mind is that light is getting bent by some sort of collision or scattering of light as it bounces off an object. That is not diffraction. Diffraction is a purely wave phenomenon that results from the mutual interference of different parts of the light wave as it passes through the aperture. It comes from no particular part of the aperture, rather it comes from all over the aperture since it is the interference of all the wave components that results in the diffraction pattern.
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Diffraction is the limiting factor in lens design. Making it irrelevant is handling it well.
You cannot make the diffraction irrelevant. You can minimise other optical aberrations so diffraction becomes the main limiting factor. Thus, in a good optical design you make diffraction highly relevant.
Diffraction is not an edge phenomenon. As it is a kind of interference it is a wave phenomenon that occurs all over the wavefront passing through the aperture. In that sense it is caused by the hole and not the edges. The other way of approaching it is probabilistically (quantum mechanics). Again it is the hole that is relevant. You cannot explain diffraction by a geometric (light ray) approach.
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Seems the point of this thread got lost in a technical discussion about diffraction, S/N ratios, etc.
Canon has released some sample images here: http://web.canon.jp/imaging/eosd/eos50d/eos50d_sample-e.html (http://web.canon.jp/imaging/eosd/eos50d/eos50d_sample-e.html)
Make of them what you will, I still expect little or no difference at f/11 between 50D and a 40D. Inerestingly, Canon has chosen a somewhat stand-offish scene shot at f/8 to illustrate the camera's landscape capabilities, which does nothing to put the DOF and Airy disc debate to rest.
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It comes from no particular part of the aperture, rather it comes from all over the aperture since it is the interference of all the wave components that results in the diffraction pattern
I don't feel comfortable to dispute a physicist's statement regarding physics, but I looked it up in the McGraw Enciylopedia of Science, which cites from "Fundamentals of Optics" by White, "Introduction to Classical and Model Optics" by Meyer-Arendt and "Lectures on Theoretical Physics" by Sommerfeld. I don't know from which source following paragraph comes:
The bending of light, or other waves, into the region of the geometrical shadow of an obstacle. More exactly, diffraction refers to any redistribution in space of the intensity of waves that results from the presence of an object that causes variation of either the amplitude or phase of the waves.
Specifically related to the Fraunhofer diffraction, it says
... At the instant that the incident plane wave occupies the plane of diffracting screen, it may be regarded as sending out, from each element of its surface, a multitude of secondary waves, the joint effect of which is to be evaluated in the focal plane of the lens.
My questions are: if I accept, that not the edge of the opening causes the diffraction but the light waves cause it on their own, then
a. how does this depend on the size of opening?
b. why does the opening exactly at the location of the aperture count, not for example the diameter of the first lens element?
c. this is expanding on b: at which point of the lens (at which point of the travel of the light rays) does the diffraction start?
I do understand, that this is far away from everyday's photography, but perhaps I am not the only one intrigued by the notion, that the presence and shape of the aperture is not the cause of diffraction.
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For comparable field of view, a 100mm lens must be on a sensor twice smaller in linear dimension than a 50mm lens; so 100mm at f11 on FF is equivalent to 50mm @ f5.6 on a half-size sensor (eg 4/3 system) in terms of diffraction effects, or a bit under f8 @ ~66mm on APS-C.
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Emil,
I think you meant to write twice bigger, didn't you?
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Canon has released some sample images here: http://web.canon.jp/imaging/eosd/eos50d/eos50d_sample-e.html (http://web.canon.jp/imaging/eosd/eos50d/eos50d_sample-e.html)
Make of them what you will, I still expect little or no difference at f/11 between 50D and a 40D.
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Using the 50D in place of the 40D at F11 (in the F8 landscape shot), just might make the difference between being able to tell the time on that tower clock and not being able to discern the position of the hands.
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I would have said that optical aberrations are the limiting factor in lens design. Diffraction is a function of f-number, and no change in the lens design is going to alter that.
From your choice of wording, I suspect that the mental construct you have in mind is that light is getting bent by some sort of collision or scattering of light as it bounces off an object. That is not diffraction. Diffraction is a purely wave phenomenon that results from the mutual interference of different parts of the light wave as it passes through the aperture. It comes from no particular part of the aperture, rather it comes from all over the aperture since it is the interference of all the wave components that results in the diffraction pattern.
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I was thinking of the 2 slit experiment that shows the waves as they propagate from small points. I understand light doesnt operate like particles. You are correct in that I was thinking the wave pattern was mainly influenced my the object (edge) that it forms around.
Your statement that its from all components sounds better that what I said which I see is wrong after thinking about your statement.
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Emil,
I think you meant to write twice bigger, didn't you?
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Yep, my bad.
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I don't feel comfortable to dispute a physicist's statement regarding physics, but I looked it up in the McGraw Enciylopedia of Science, which cites from "Fundamentals of Optics" by White, "Introduction to Classical and Model Optics" by Meyer-Arendt and "Lectures on Theoretical Physics" by Sommerfeld. I don't know from which source following paragraph comes:
The bending of light, or other waves, into the region of the geometrical shadow of an obstacle. More exactly, diffraction refers to any redistribution in space of the intensity of waves that results from the presence of an object that causes variation of either the amplitude or phase of the waves.
Specifically related to the Fraunhofer diffraction, it says
... At the instant that the incident plane wave occupies the plane of diffracting screen, it may be regarded as sending out, from each element of its surface, a multitude of secondary waves, the joint effect of which is to be evaluated in the focal plane of the lens.
This last statement is to me the important intuition, known as Huyghens' principle -- the idea that each point along a wave's oscillation is a source for the further propagation of the wave. Consider dropping a stone into a pond. The stone oscillates the surface of the water up and down at the point of impact, resulting in a spherical wave travelling out on the surface of the water. Consider as well a point on the surface away from the point of impact; as the wave passes by, it oscillates the surface of the water up and down -- so each point along the wave is itself a source for further propagation of the wave, as each point oscillates up and down it sends out spherical waves of its own which combine to make the wave which is seen a little later.
In diffraction, what happens is that only the wave at the aperture are present, all the other points along the wavefront having been blocked by the obstacle/aperture. Each point along the opening sends out its little spherical wave, and so in particular sends light into the region which one might naively think is in the shadow of the obstacle. The wider the opening, the more of the incident wavefront is present, and the more these little spherical waves from all along the wavefront cohere to make a forward propagating wave (with a slight spread from the diffraction). The narrower the opening, the more the further propagation comes from almost a single point, and so the more the further propagation emanates out spherically like the pebble in the pond rather than in the forward direction which one would naively think is the direction the light should be going.
Note that, according to Huyghens, the further wave pattern comes from the pattern created by propagation from all along the wavefront, not just at the edges of the obstacle.
There are different levels of approximation in the calculation of diffraction effects. The leading order approximation is called Fraunhofer diffraction, and is the sort that goes on when light passes through a small aperture. The next order is known as Fresnel diffraction, and is more relevant to diffraction effects in the shadow of an obstacle. The next order beyond that is relevant to the formation of supernumerary rainbows, a rare occurance but beautiful to see when it happens.
My questions are: if I accept, that not the edge of the opening causes the diffraction but the light waves cause it on their own, then
a. how does this depend on the size of opening?
b. why does the opening exactly at the location of the aperture count, not for example the diameter of the first lens element?
c. this is expanding on b: at which point of the lens (at which point of the travel of the light rays) does the diffraction start?
I do understand, that this is far away from everyday's photography, but perhaps I am not the only one intrigued by the notion, that the presence and shape of the aperture is not the cause of diffraction.
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a. The angle over which the beam spreads is inversely proportional to the diameter of the aperture.
b. All elements in the optical path will generate some diffraction, however given the relation of the spreading angle to the aperture size, it is the smallest constriction in the light path which has the dominant effect.
c. I suppose you could say that it starts at the lens hood, but really the amount of diffraction there is negligible; it is the smallest opening, the aperture itself, which has the most important effect.
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Emil,
thanks for the detailed explanation. I will chew on that later; however, now I have a question of practical relevance.
The claim, that the diffraction depends only on the f-number is based on a woodoo calculation: it starts out with a thin lens and puts the aperture directly to the lens, ignoring the distance between the aperture and the center plane of the lens (from where the focal length is measured in case of the thin lens). There is no such design in today's photography.
If the location of the aperture is the main "starting point" of the diffraction, then the aperture-focal plane distance should be used in the calculation, which is usually far from the focal length. This is true re both short and long focal lengths; the location of the aperture is at the second nodal plane only in particular retrofocal configurations.
Thus the statement, that the diffraction depends on the f-number is not correct. In fact, it does not depend on the focal length at all.
Another issue is, that the light does not travel in a straight line between the aperture and the focal plane. It changes the direction several times, there is even a convergence point in-between.
I have the feeling that the drawing (and associated calculation) illustrating the correlation between aperture, focal length and focal plane is meant for the kindergarten. It stank already, when I saw sin(x) substituted by x (for example in Sidney Ray's Applied Photographic Optics); x must be several orders smaller for this substitution than it is in the cases we are talking about. This has nothing to do with the dependance/independance of the diffraction on/from the focal length, but it does have to do with the diameter of the airy disk.
What do you think of that?
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Using the 50D in place of the 40D at F11 (in the F8 landscape shot), just might make the difference between being able to tell the time on that tower clock and not being able to discern the position of the hands.
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You just don't get it, or choose not to believe what I'm asserting. f/11 is going to be more blurry than f/8, and you will probably no longer be able to make out the hands on the clock, and that will be the same as what 40D resolves.
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I understand light doesnt operate like particles.
[a href=\"index.php?act=findpost&pid=218583\"][{POST_SNAPBACK}][/a]
You can approach this phenomena from the particle point of view (quantum mechanics, quantum interference). But then you have to think in terms of probabilities not what happens to a single particle.
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f/11 is going to be more blurry than f/8, and you will probably no longer be able to make out the hands on the clock, and that will be the same as what 40D resolves.
[a href=\"index.php?act=findpost&pid=218626\"][{POST_SNAPBACK}][/a]
The first phrase in your sentence is probably correct (with most of today's lenses). But how do you infer the correctness of the third phrase?
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You just don't get it, or choose not to believe what I'm asserting. f/11 is going to be more blurry than f/8, and you will probably no longer be able to make out the hands on the clock, and that will be the same as what 40D resolves.
[a href=\"index.php?act=findpost&pid=218626\"][{POST_SNAPBACK}][/a]
No. You haven't interpreted correctly what I wrote. I'll try again. In circumstances where at F11 the time on that tower clock (the tower clock as identified in the F8 shot) is just legible in a 50D shot, it probably wouldn't be legible in a 40D shot at the same aperture of F11.
Of course I know that all good 35mm lenses will be marginally sharper at F8 than at F11. Why on earth would you think I wasn't aware of that?
However, some budget priced zooms are sharpest at F16, at certain focal lengths, which is another issue.
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Emil,
thanks for the detailed explanation. I will chew on that later; however, now I have a question of practical relevance.
The claim, that the diffraction depends only on the f-number is based on a woodoo calculation: it starts out with a thin lens and puts the aperture directly to the lens, ignoring the distance between the aperture and the center plane of the lens (from where the focal length is measured in case of the thin lens). There is no such design in today's photography.
If the location of the aperture is the main "starting point" of the diffraction, then the aperture-focal plane distance should be used in the calculation, which is usually far from the focal length. This is true re both short and long focal lengths; the location of the aperture is at the second nodal plane only in particular retrofocal configurations.
Thus the statement, that the diffraction depends on the f-number is not correct. In fact, it does not depend on the focal length at all.
Another issue is, that the light does not travel in a straight line between the aperture and the focal plane. It changes the direction several times, there is even a convergence point in-between.
I have the feeling that the drawing (and associated calculation) illustrating the correlation between aperture, focal length and focal plane is meant for the kindergarten. It stank already, when I saw sin(x) substituted by x (for example in Sidney Ray's Applied Photographic Optics); x must be several orders smaller for this substitution than it is in the cases we are talking about. This has nothing to do with the dependance/independance of the diffraction on/from the focal length, but it does have to do with the diameter of the airy disk.
What do you think of that?
[a href=\"index.php?act=findpost&pid=218610\"][{POST_SNAPBACK}][/a]
I wouldn't characterize it as a voodoo calculation, rather it is the sort of reasonable simplifying approximation that is made in physical models. It is however important to understand what those simplifying assumptions are and how they affect the result.
For instance, in the oft-quoted formula for the location of the first minimum of the diffraction pattern (the size of the Airy disk), at 1.22*wavelength/f-number, the assumption is not only that the aperture is located at the focal length from the focal plane, also the 1.22 comes from assuming that the aperture is circular rather than hexagonal or octagonal (as for a real lens aperture); and as you are pointing out, there is a sequence of obstructions along the light path through the lens, each of which will contribute to diffraction effects.
All that a more refined calculation, using the actual configuration of a specific camera lens, will accomplish is to refine that numerical factor 1.22 into something slightly different.
How different is the aperture-to-focal plane distance from the focal length in a typical lens? Does the ratio of these two quantities vary substantially from lens to lens? I'm not knowledgeable about the details of current lens designs.
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I wouldn't characterize it as a voodoo calculation, rather it is the sort of reasonable simplifying approximation that is made in physical models
I characterize it that way, for I don't find anything reasonable on it. There is nothing there related to real photographic lenses; though you may use that method when calculating the diffraction of a loupe.
How different is the aperture-to-focal plane distance from the focal length in a typical lens? Does the ratio of these two quantities vary substantially from lens to lens? I'm not knowledgeable about the details of current lens designs.
The block diagrams of almost all Canon lenses are shown in Canon's Camera Museum; one can roughly estimate the position of aperture from the flange.
The flange-focal plane distance is about 36mm (rough measurement, for I was careful with the vernier caliper inside the chamber). I made a search for it and found 44mm; no way (anyway, this is relevant only for the calculation with specific lenses, not in general).
My estimation is, that the aperture/focal plane distance is close to the focal length in case of the 50mm lenses: about 55mm with the 50mm f/1.4. In case of the ultrawides, like the 14mm f/2.8L the aperture may be more than four times the focal length away. The proportion turns around with the long lenses; for example the 200mm f/2.8L: the aperture appears to be around 90mm away from the focal plane, with the 300mm f/2.8L IS this appears to be 120mm, with the 400mm it is about 130mm, roughly 1/3 of the focal length.
Thus there is a factor of at least twelve between the lenses, even more between extreme short and extreme long ones.
Good by airy disk calculation based on the f-number.
(And we have no idea yet, how the multiple bending of the rays affects the outcome.)
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No. You haven't interpreted correctly what I wrote. I'll try again. In circumstances where at F11 the time on that tower clock (the tower clock as identified in the F8 shot) is just legible in a 50D shot, it probably wouldn't be legible in a 40D shot at the same aperture of F11.[a href=\"index.php?act=findpost&pid=218633\"][{POST_SNAPBACK}][/a]
You wrongly assume that the 50D will not lose acuity at f/11 and will still show the hands on the clock. If the hands can no longer be seen at f/11 on the 50D, then you have gained nothing over the 40D.
Of course I know that all good 35mm lenses will be marginally sharper at F8 than at F11. Why on earth would you think I wasn't aware of that?
Regardless of lens, the denser photosites will become the limiting factor even with the best lens. Is the Airy disk eliminated with a higher quality lens? Canon shot this landscape scene at f/8 and I believe that wasn't a random choice that they made. Probably with the lens they used f/5.6 would have had softer corners, and I bet they saw that the f/8 shot was sharper than the f/11 shot (and maybe even the f/9 shot). Does this mean that the 40D is just as good at f/11 as the 50D? Hard to say: AA filters, microlenses, and the lenses used will all play a part in the final outcome; but I still think at f/11 diffraction (as recorded by the photosites) will limit the files to about equal.
I have two excellent landscape lenses: the Nikkor 14-24/2.8 and the Nikkor 17-35/2.8 -- that's because I bought the latter when money was tighter and it has been banged around (so it only cost me about $500), and now my son uses it on his D200. I had noticed using the 17-35 that it was always a little soft in the corners at infinity using the hyperfocal distance, but sharp focused at infinity. The 14-24 on the other hand is actually sharper at infinity using hyperfocal distance than it is focused at infinity, but only at around f/11. Here's the rub, when I set the lens to a wider aperture and use the hyperfocal distance then my edges (but not the center) at infinity start softening up. So if I were offered a Nikon DX DSLR that had 15 MP I would gain nothing whatsoever over my D300 because I need to shoot at f/11 to get the most out of my lens and the edges of my landscape photographs would be less sharp at f/8.
I have some excellent lenses, but I will not upgrade to a 24 MP FX DSLR until I have spent over $5000 on 3 more lenses that I consider essential for attaining optimum image quality (24mm and 45mm PCE, and the Nikkor 24-70/2.8). Also, I will be upgrading my computer because as it is now my system bogs down when I start assembling and editing 20+ MP images, and that's probably another $4000. I think chasing megapixels without giving careful consideration to what you will do with them is foolhardy -- YMMV.
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You wrongly assume that the 50D will not lose acuity at f/11 and will still show the hands on the clock. If the hands can no longer be seen at f/11 on the 50D, then you have gained nothing over the 40D.
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Tony,
It's not a wrong assumption that the 50D will not lose acuity at F11 or F22 or any aperture you wish to nominate. The acuity of the 50D sensor is fixed. Only the lens will lose acuity as it is stopped down beyond F8.
It's been mentioned several times in this thread that there is some evidence that the higher-pixel-density sensor can continue to provided marginally (perhaps very marginally) greater detail all the way to F32, despite the fact that the theoretical calculation of the size of the Airy disc at such apertures suggests there is nothing to be gained.
My own experience suggests that the contrast of the target will also affect any test results significantly. This is another source of confusion which (for example) prompts many questions about the effectiveness of 1.4x and 2x extenders with a particular lens.
Such questions can never be answered definitively, because it always depends... depends on the contrast and detail of the target as well as the quality of the lens.
After acquiring my Canon 100-400 zoom and 1.4x converter, I took many test shots of distant subjects, with and without converter at 400mm. Even at 200% magnification on the monitor, often I could not see any improvement in detail or sharpness.
However, when shooting closer subjects of high detatail and contrast in bright sunlight, there was always a noticeable improvement using the 1.4x extender.
I imagine the same principle applies when using small apertures with high-pixel-density cameras. There is no brick wall, just a gradual loss of contrast as one stops down. At some point, with a low contrast subject, one will be unable to perceive any improvement in detail or sharpness from the higher-pixel-density sensor. Change the subject (or target) to one of very high contrast, then detail that previously was indiscernible at the same F stop (say F11 or F16) becomes discernible.
I can to some extent sympathaise with your point of view. I was also of the opinion that there's nothing to be gained at diffraction limited apertures with the higher-pixel-count cameras. This is of some concern to me since I have my eye on one of the next 24mp FF cameras which have approximately the same pixel density as my 40D. I was curious if any purpose would be served at F16 and F22, apertures which I can use with my 5D but would hesitate to use with the 40D.
Some of my test results can be found at [a href=\"http://luminous-landscape.com/forum/index.php?showtopic=26420]http://luminous-landscape.com/forum/index....showtopic=26420[/url] , a thread started by dwdallam who was apparently concerned about the performance of his 1Ds3 at such apertures.
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It is my contention that by the time you reach f/11, there will be no difference between a 40D file and a 50D file.
[a href=\"index.php?act=findpost&pid=217510\"][{POST_SNAPBACK}][/a]
Assuming you're correct, that still leaves an awful lot of subjects shot at f8 or wider where, I think you would agree, the 50D would show an advantage. I would hazard a guess that well over half of my photos are shot at f8 or greater.
Time will tell how the camera stands up to Canon's claims, but I believe it appears to be a significant advance over the prior xxD bodies. Would applying the new microlens technology to a 12 mp sensor have been a better alternative? Perhaps for some, but maybe not for all.
As long as image quality at f11 and smaller is not WORSE than the 40D, I'll take the improved resolution at larger apertures, along with improved live view, lens microfocus adjust, the higher res LCD, etc. In fact, if this camera lives up to the hype, it's the first xxD body that offers enough of an advance to make me replace my 20D. I'll give it to my wife, keep the 1DII for situations where AF performance is the highest priority, and use the 50D for everything else. IF the camera lives up to Canon's hype.
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Assuming you're correct, that still leaves an awful lot of subjects shot at f8 or wider where, I think you would agree, the 50D would show an advantage. [a href=\"index.php?act=findpost&pid=218810\"][{POST_SNAPBACK}][/a]
Absolutely! We should bear in mind that F8 on the Canon cropped format is equivalent to F13 on full frame 35mm, regarding DoF. Even if the lens used is sharpest at F5.6, that's still equivalent to a 35mm F9.
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The MP seems pointless and counterproductive to me. Very very few lenses are good enough to use 15MP. And I'm not talking just resolution on axis, but corner resolution, and CA. And even then, they can only use that 15MP when at about F8. So, how many shots do you take with the finest lens, on a solid tripod, with perfect technique, at low ISO (so as not to lose IQ) and F8? Very few is my guess. And yet you need to store 15MP files. Oh, and how big do you need to print to see the advantage over 12MP?
Nice camera though in terms of the other specs i.e. build, FPS, AF etc. Looks like Canon have finally caught up with Nikon by selling an APS camera with a high price. I always though the 40D was more than enough though.
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So, how many shots do you take with the finest lens, on a solid tripod, with perfect technique, at low ISO (so as not to lose IQ) and F8? Very few is my guess
Most of my shots. The exception is, when I can shoot it hand-held, but ISO 200, f/8 or f/11.
And yet you need to store 15MP files
I don't see any problem there.
I always though the 40D was more than enough though.
More than enough of what? Pixels? Already the 20D was enough for me. Dynamic range? The 40D is far from what I would like to have.
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Most of my shots. The exception is, when I can shoot it hand-held, but ISO 200, f/8 or f/11.
I don't see any problem there.
More than enough of what? Pixels? Already the 20D was enough for me. Dynamic range? The 40D is far from what I would like to have.
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I think you are the exception in terms of technique. Okay, so you seem to agree that the extra MP is not of interest to you. Dynamic range? Yes, we can all hope! Though for me the extra DR over slide film, and the ease of getting white balance without CC filters makes digital a winner.
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I think you are the exception in terms of technique
Are you never shooting landscapes?
Though for me the extra DR over slide film, and the ease of getting white balance without CC filters makes digital a winner
Well, Morse was a winner over letters carried by couriers, so why are we having phone, fax, email, mobile phone?
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I think you are the exception in terms of technique. Okay, so you seem to agree that the extra MP is not of interest to you. Dynamic range? Yes, we can all hope! Though for me the extra DR over slide film, and the ease of getting white balance without CC filters makes digital a winner.
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At the risk of intruding on the thread, whilst Panopeepers technique is unusual it is also the reason he doesn't need more pixels. Since I suspect that he specialises in panoramas he can get as many pixels as he needs by chooisng the most appropriate lens.
On the 50D, I looked at the landscape sample as was a bit disappointed actualy. That may just be the subject, but I'de expected better given the hype.
Mike - a happy canon user!
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At the risk of intruding on the thread, whilst Panopeepers technique is unusual it is also the reason he doesn't need more pixels. Since I suspect that he specialises in panoramas he can get as many pixels as he needs by chooisng the most appropriate lens.
On the 50D, I looked at the landscape sample as was a bit disappointed actualy. That may just be the subject, but I'de expected better given the hype.
Mike - a happy canon user!
[a href=\"index.php?act=findpost&pid=219025\"][{POST_SNAPBACK}][/a]
I also shoot a lot of panos....actually most of my serious photo work is panoramic. Right now, with an 8MP camera I can make a single row pano up to about 14" tall by any dimension wide. My largest work was 7 rows of 9 images.
To get up to 17" or even 24" I need to shoot mosaics of multiple rows. This requires a more complex tripod head (spherical versus cylindrical) which adds more weight to my gear. I am hoping that the 50D resolution is enough to allow me to get something like a 20" tall panoramic print with only a single row of images. At 240 DPI, if the 50D images benefit from all of its available resolution, I could print up to 19.8" tall. If I am limited to F/8 or F/11, that would be acceptable to me.
Pano people are obsessed with large detailed images...I guess that is why he is so concerned with resolution that goes beyond useful resolving power of the sensor/lens combo.
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Pixel count is often less a concern in panomaking than in "normal" landscaping, although if I can I avoid shooting two rows instead of a single row only for the sake of a few hundred extra pixels.
Dynamic range is a bigger issue in panomaking. The dynamic range of a wide (or tall, for that matter) scenery may exceed by a lot that of a single frame. Although I often shoot the frames with variable exposure, this involves quite much preparatory work for the stitching; it is much simpler to shoot all frames with the same exposure - but then one needs sometimes three stops extra DR.
However, shooting from tripod with low ISO, aperture as small as diffraction allows and still ideal exposure is IMO nothing special in landscape shooting. For me the biggest issue (beside the DR) is in most cases the compromise between DoF and diffraction.
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Perhaps someone could provide some test shots comparing image sharpness of the same scene at various ISOs. I get a sense there's a slight drop in resolution at ISO 800 and 1600 with the 5D, but do not hesitate to use ISO 400 when needed for the required shutter speed.
The 'sunny 16' rule indicates that correct exposure for an open landscape on a sunny day is 1/ISO. At ISO 100 that's 1/100th of a second at F16 and 1/400th at F8. I see no problem there.
Choosing a sufficiently fast shutter speed for a sharp image is a basic photographic technique. Unfortunately, circumstances are such that it's sometimes not possible, due to poor lighting. Using a tripod doesn't necessarily help if the subject is moving.
One feature which I'd find very useful, which I believe only certain Nikon cameras offer, is automatic ISO in relation to a chosen shutter speed and aperture. I can't understand why Canon do not offer this feature now that DSLRs produce such excellent image quality at high ISO. Even with an IS lens, I'd rather use 1/100th at ISO 800 than 1/13th at ISO 100, hand-held. With a telephoto lens, say 400mm with image stabilisation, I'd rather use 1/400th at ISO 1600 than 1/200th at ISO 800.
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The 'sunny 16' rule indicates that correct exposure for an open landscape on a sunny day is 1/ISO
What is the role of in-camera RGB histogram in the "sunny 16" rule?
Even with an IS lens, I'd rather use 1/100th at ISO 800 than 1/13th at ISO 100, hand-held. With a telephoto lens, say 400mm with image stabilisation, I'd rather use 1/400th at ISO 1600 than 1/200th at ISO 800.
You mentioned a "sunny day" just above. What about the dynamic range?
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I have a question for you all:
5D or 50D if you had to choose one or the other?
And just for giggles---Digic 4 processor and the Digic 3 has been out less than a year. I feel ripped off with my 1DS3. Can you image the 1DS3 with the Digic 4? I can, but I just bought the 1DS3. I knew I should have waited a year to upgrade.
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What is the role of in-camera RGB histogram in the "sunny 16" rule?
To make sure those fluffy white clouds are not clipped.
You mentioned a "sunny day" just above. What about the dynamic range?
I don't believe even an MFDB will capture dense, undergrowth shadows cleanly with unclipped, fluffy white clouds in the same scene.
I would not expect the 50D, considering the image as a whole at a specific size on monitor or print, to have less dynamic range than the 40D, although the individual pixels might have very slightly less.
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And just for giggles---Digic 4 processor and the Digic 3 has been out less than a year. I feel ripped off with my 1DS3. Can you image the 1DS3 with the Digic 4? I can, but I just bought the 1DS3. I knew I should have waited a year to upgrade.
[a href=\"index.php?act=findpost&pid=219117\"][{POST_SNAPBACK}][/a]
Isn't the Digic processor only relevant for jpeg shooters?
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I believe it is what peels everything off the sensor. So if it is slow you're RAW frame rates will suffer.
I should think that it would also matter for live view.
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To make sure those fluffy white clouds are not clipped
LOL, that's what I meant. I don't need Noah's rule when I have a built-in metering and histogram.
I don't believe even an MFDB will capture dense, undergrowth shadows cleanly with unclipped, fluffy white clouds in the same scene
Such general statements are not of much help. Anyway, irrespectively of the total dynamic range of the scenery, two stops more or less make a huge difference for me (that is the difference between ISO 200 and 1600 of the 40D's DR).
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I have a question for you all:
5D or 50D if you had to choose one or the other?
Is this not too early? Based on what would one make a decision?
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Isn't the Digic processor only relevant for jpeg shooters?
[a href=\"index.php?act=findpost&pid=219170\"][{POST_SNAPBACK}][/a]
While I know that RAW is considered...well...the raw data, I seriously doubt that the data is taken without any processing at all....just encapsulating the data into a file format, applying metadata and saving the file to compact flash would be some minimal processing task for the DIGIC...that doesn't include the exposure curve and white balance that is applied to the RAW file so that it doesn't look like cr@p when we view it.
It wouldn't be surprising if some very conservative, baseline sharpening and noise reduction was happening too.
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Have you seen the 50D samples at DPreview? If that is the level of jpeg sharpening I feel pretty confident that the RAW files will have none applied.
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While I know that RAW is considered...well...the raw data, I seriously doubt that the data is taken without any processing at all....just encapsulating the data into a file format, applying metadata and saving the file to compact flash would be some minimal processing task for the DIGIC...that doesn't include the exposure curve and white balance that is applied to the RAW file so that it doesn't look like cr@p when we view it.
It wouldn't be surprising if some very conservative, baseline sharpening and noise reduction was happening too.
[a href=\"index.php?act=findpost&pid=219193\"][{POST_SNAPBACK}][/a]
There is no exposure curve or white balance applied to the raw data; that is the purpose of the metadata -- to specify the chosen picture style (tone curve) and the white balance determined by the camera's metering, for the raw converter to make use of (or not). There is also no sharpening or NR applied to Canon raw data unless one turns on long exposure NR.
This is not to say that there isn't processing of the pixel data before a RAW is written; it's just that the processing is at the level of individual pixels (for instance, the correlated double sampling that removes pixel reset fluctuations from the pixel values) rather than the sorts of manipulations one typically does in post-processing.
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LOL, that's what I meant. I don't need Noah's rule when I have a built-in metering and histogram.
I wasn't suggesting you do. I was addressing the negative attitude that a higher pixel count might be disadvantageous because to realise the potentialy higher resolution one would need to use faster shutter speeds. My sunny 16 rule was an example of how fast shutter speeds can be when the light is good.
Such general statements are not of much help. Anyway, irrespectively of the total dynamic range of the scenery, two stops more or less make a huge difference for me (that is the difference between ISO 200 and 1600 of the 40D's DR).
The dynamic range of subject brightness in the real world can be huge; far greater than any current camera can capture in a single shot. I imagine that the DR of the 40D at ISO 1600 is at least as good as that of slide film in the days of yore.
I think we might have to wait for a shift in paradigm and/or some new breakthrough technology before we see a substantial improvement in the DR of digital cameras.
One rather dismaying fact about the Bayer type sensor is that it necessarily has to block out about half the light it receives, perhaps as much as 2/3rds depending on scene content. There's at least a whole stop of DR thrown away as a result of the need for color filters.
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I wasn't suggesting you do. I was addressing the negative attitude that a higher pixel count might be disadvantageous because to realise the potentialy higher resolution one would need to use faster shutter speeds. My sunny 16 rule was an example of how fast shutter speeds can be when the light is good
You have a sure way to turn anything into an umitigated rubbish.
The dynamic range of subject brightness in the real world can be huge; far greater than any current camera can capture in a single shot. I imagine that the DR of the 40D at ISO 1600 is at least as good as that of slide film in the days of yore
See above.
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You have a sure way to turn anything into an umitigated rubbish.
See above.
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You sure have a strange definition of rubbish.
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I have just spent the last few minutes reading this entire thread. Some excellent content and information from both sides of the argument.
I do wonder though, if people go into such depths about pixel count, diffraction etc and so on, does it take over from the ultimate goal which is taking photographs - it's almost like having the ultimate high performance car, but constantly taking the engine out instead of driving it.
Still a good thread though
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After we get the DPreview of the technical capabilities of the 50D, I was thinking about selling my 5D and getting the 50D. The problem is, if it produces images as good as the 5D in tonality and noise, who would buy a 5D?
On the upside, the body is only 1400.00US so that's good news.
I also wonder if it's weather sealing is the same as the 1D series cameras, or if it's a lesser sort?
Other than being a crop frame camera, if the sealing, shutter release time to failure, and image reproduction are as good as the 5D, plus you get 15MP--what a great camera for the price.
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http://forums.dpreview.com/forums/read.asp...essage=29193081 (http://forums.dpreview.com/forums/read.asp?forum=1019&message=29193081)
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After we get the DPreview of the technical capabilities of the 50D, I was thinking about selling my 5D and getting the 50D. The problem is, if it produces images as good as the 5D in tonality and noise, who would buy a 5D?
[a href=\"index.php?act=findpost&pid=219371\"][{POST_SNAPBACK}][/a]
The best sensor in photon collecting efficiency per unit area is currently the D3; it beats the current Canons (1D3, 1Ds3, and 40D) by about 15%, probably due to its gapless microlenses, and it beats the 5D by a factor 1.5. So, if the 50D with its gapless microlenses achieves the sensitivity of the D3, it still loses by a factor 1.75 in light-collecting ability relative to the 5D because the APS-C format is so much smaller than full frame (less than 40% of the area). So unless the new sensor is 2/3 stop more efficient than the 5D (a true technological breakthrough), it will not be even close in image quality to the 5D.
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You have a sure way to turn anything into an umitigated rubbish.
See above.
[a href=\"index.php?act=findpost&pid=219311\"][{POST_SNAPBACK}][/a]
Amen.
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You have a sure way to turn anything into an umitigated rubbish.
See above.
Amen.
[a href=\"index.php?act=findpost&pid=219477\"][{POST_SNAPBACK}][/a]
In my experience, I have found when people resort to such abusive language it is usually because they either have not been able to understand the argument, have been able to understand the argument but don't like it even though the argument is sound, or are simply not man enough to admit they might be wrong.
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I haven't been able to read any comments as to any improvements in the weather sealing of the 50D.
I think one of the main failings of the 40D compared to the D300 was quality of craftsmanship. If two cameras are relatively equivalent in output, the better-built camera becomes the more attractive buy.
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I haven't been able to read any comments as to any improvements in the weather sealing of the 50D.
I think one of the main failings of the 40D compared to the D300 was quality of craftsmanship. If two cameras are relatively equivalent in output, the better-built camera becomes the more attractive buy.
[a href=\"index.php?act=findpost&pid=220357\"][{POST_SNAPBACK}][/a]
I'd argue that the cheaper one becomes the more attractive buy.
It is my understanding that there are weather sealing improvements. Check the dpreview preview.
Phil Askey: "Apparently (we've been told verbally) the 50D's body offers better environmental sealing than the EOS 40D thanks to a slightly different construction and tighter seals. We'll get more information on this as soon as we can."
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http://forums.dpreview.com/forums/read.asp...essage=29327398 (http://forums.dpreview.com/forums/read.asp?forum=1019&message=29327398)
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http://forums.dpreview.com/forums/read.asp...essage=29327398 (http://forums.dpreview.com/forums/read.asp?forum=1019&message=29327398)
[a href=\"index.php?act=findpost&pid=221562\"][{POST_SNAPBACK}][/a]
Those look very good! The picture of the billboard shows really good transitions into pure black shadows. There isn't too much detail in the shadows, but that shot was taken at 1/125 at f/4.5, so it isn't like they could have pulled much more detail out of the shadows by changing the aperture or shutter speed--at least while remaining at handheld speeds.
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Those look very good! The picture of the billboard shows really good transitions into pure black shadows. There isn't too much detail in the shadows, but that shot was taken at 1/125 at f/4.5, so it isn't like they could have pulled much more detail out of the shadows by changing the aperture or shutter speed--at least while remaining at handheld speeds.
[a href=\"index.php?act=findpost&pid=221583\"][{POST_SNAPBACK}][/a]
I still want to see raw files. But all in all it is looking pretty good.
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It is amazing. I don't mean the sample shots, but how people interpret images, which are totally meaningless regarding the camera's capability. Nothing but absolutely nothing can be judged based on these shots.
I analyzed a few raw files, which were shot in a photoshop; the shots suck, the photog did not have any comparison in mind. However, some are suitable for measuring the noise. It is on par with the 40D.
In other words: the technology is better than that of the 40D, Canon could have increased the DR, but they decided to go for the pixels. Sux.
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It is amazing. I don't mean the sample shots, but how people interpret images, which are totally meaningless regarding the camera's capability. Nothing but absolutely nothing can be judged based on these shots.
I analyzed a few raw files, which were shot in a photoshop; the shots suck, the photog did not have any comparison in mind. However, some are suitable for measuring the noise. It is on par with the 40D.
In other words: the technology is better than that of the 40D, Canon could have increased the DR, but they decided to go for the pixels. Sux.
[a href=\"index.php?act=findpost&pid=221604\"][{POST_SNAPBACK}][/a]
You are right, in the balance of tradeoffs, they chose the easy way to market the camera--with simplistic megapixels. The general public likes a simple story. Perhaps they could have further improved DR or high-ISO noise levels, but what they did achieve is that they didn't backslide towards worse noise-levels or lower DR--in fact it will probably be slightly better. I can agree with you that perhaps I would choose 14MP or 12MP with better DR and noise characteristics, but they didn't do that and that is that. I think you are beating a dead horse. The new camera seems to be better than the old--maybe not in the way that gabor would like--but better.
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It is amazing. I don't mean the sample shots, but how people interpret images, which are totally meaningless regarding the camera's capability. Nothing but absolutely nothing can be judged based on these shots.
I analyzed a few raw files, which were shot in a photoshop; the shots suck, the photog did not have any comparison in mind. However, some are suitable for measuring the noise. It is on par with the 40D.
In other words: the technology is better than that of the 40D, Canon could have increased the DR, but they decided to go for the pixels. Sux.
[a href=\"index.php?act=findpost&pid=221604\"][{POST_SNAPBACK}][/a]
Just out of curiousity, Panokeeper, how did you examine these files??? Everyone has their own interpretation of things. I downloaded the Canon images, especially the landscape one, as that is what I shoot mainly. Resized it in CS3 and printed out 36" crops. To my eyes, [20-20] looking at 12+" this file looks great. Not quite the smoothness of my 5D images but on printed image, not bad at all. Certainly a good step over the 40D images I had. ....
Everyone has their own standards, but I find actual print the most fair and accurate to go by in deciding my own needs....fwiw, if the aps-c chip and processor is this good, I think this bodes well for the new FF with digic 4.....ymmv...jmho
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how did you examine these files???
I am measuring the noise (as standard deviation) on smooth, unicolor, evenly lit areas, on the non-demosaiced raw data. Any image is good, which contains such spots in the very dark shadows.
The images I received are not very suitable for this purpose, but I did find a few spots good enough to measure.
I am working on a collection of such measurements with different cameras; I will post it when it is so far. Perhaps more suitable raw files from the 50D will appear in the meantime.
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After we get the DPreview of the technical capabilities of the 50D, I was thinking about selling my 5D and getting the 50D. The problem is, if it produces images as good as the 5D in tonality and noise, who would buy a 5D?
On the upside, the body is only 1400.00US so that's good news.
I also wonder if it's weather sealing is the same as the 1D series cameras, or if it's a lesser sort?
Other than being a crop frame camera, if the sealing, shutter release time to failure, and image reproduction are as good as the 5D, plus you get 15MP--what a great camera for the price.
[a href=\"index.php?act=findpost&pid=219371\"][{POST_SNAPBACK}][/a]
Nobody will buy a (new) 5D very soon, because it is about to be discontinued in favor of its replacement. Let us remember the aging within the product cycle when we make these comparisons.
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Nobody will buy a (new) 5D very soon, because it is about to be discontinued in favor of its replacement. Let us remember the aging within the product cycle when we make these comparisons.
[a href=\"index.php?act=findpost&pid=221646\"][{POST_SNAPBACK}][/a]
I'm thinking about buying the old 5D---as soon as the new one comes out, the 50D comes out, and the 5D drops below 2Gs in price
Regardless of all the "new innovations," the old 5D is a wonderful camera, and it will still take stellar shots, and very soon at about half the price
Heh-heh ...
Jack
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I'm thinking about buying the old 5D---as soon as the new one comes out, the 50D comes out, and the 5D drops below 2Gs in price
Regardless of all the "new innovations," the old 5D is a wonderful camera, and it will still take stellar shots, and very soon at about half the price
Heh-heh ...
Jack
.
[a href=\"index.php?act=findpost&pid=221661\"][{POST_SNAPBACK}][/a]
Geeze I thought it was already down past 2K. It has held it's price well. And I agree with others. It is a very nice camera and its noise levels are low, especially considering when it came out. It was surely a slam dunk for Canon.