Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Dasher on January 13, 2007, 04:41:31 pm

Title: My primes not as sharp as zooms, huh?!?
Post by: Dasher on January 13, 2007, 04:41:31 pm
Hi,

I switched to a Canon 5D about 4 months ago and just started comparing my lenses as I have a few that overlap and wanted to find out which served it's purpose best. As I also have the 17-40 zoom, I thought I could sell it off as I have the "sharp" primes as well. With my 10D I never noticed, but it doesn't use most of the edges.

What I found out is that my 20/2.8, 24/2.8 and 35/2.0 primes all performed poorly in the corners and edges in comparisson to my 17-40 and 24-105 zooms. I get the same sharpness (in corners) with the primes at f11 that I get with my zooms at f5.6. Above f16 the primes start to lose contrast and become soft, so it is no option for me to go f22 and up.

Does anyone have similar experiences? Does the 35/1.4L fare any better than it's  older siblings?

http://dasher.cc/foto/17-40_056.jpg (http://dasher.cc/foto/17-40_056.jpg)
17-40mm on 24mm at f5.6/1s

http://dasher.cc/foto/24_056.jpg (http://dasher.cc/foto/24_056.jpg)
24mm at f5.6/1s

http://dasher.cc/foto/24_110.jpg (http://dasher.cc/foto/24_110.jpg)
24mm at f11/4s


Photos taken on ISO50, MLU and remote on top of a Gitzo G1500.
Title: My primes not as sharp as zooms, huh?!?
Post by: jani on January 13, 2007, 06:09:37 pm
Quote
I switched to a Canon 5D about 4 months ago and just started comparing my lenses as I have a few that overlap and wanted to find out which served it's purpose best. As I also have the 17-40 zoom, I thought I could sell it off as I have the "sharp" primes as well. With my 10D I never noticed, but it doesn't use most of the edges.

What I found out is that my 20/2.8, 24/2.8 and 35/2.0 primes all performed poorly in the corners and edges in comparisson to my 17-40 and 24-105 zooms. I get the same sharpness (in corners) with the primes at f11 that I get with my zooms at f5.6. Above f16 the primes start to lose contrast and become soft, so it is no option for me to go f22 and up.

Does anyone have similar experiences?
In 2004, Per Inge Østmoen tested the following lenses:

EF 20mm f/2.8 USM
EF 28mm f/2.8
EF 35mm f/2.0
EF 17-40mm f/4L USM
EF-S 18-55mm f/3.5-5.6

While you probably can't read Norwegian, the images are labeled with the lens names, and you should get the gist of it:

Test of two Canon zoom and three prime lenses (http://www.akam.no/test/objektiver/test_av_to_canon-zoomer_og_tre_fastobjektiver/5417/1)

Basically, yes, the EF 17-40mm f/4L performs well compared to these specific primes.

He didn't test the EF 35mm f/1.4L under the same conditions, as far as I know.


Personally, I only have experience with the 17-40mm f/4L, which while a decent zoom lens has some very obvious vignetting when on a 5D, clearly visible through the viewfinder. But then it was launched by Canon as a "digital" lens.

Quote
http://dasher.cc/foto/24_056.jpg (http://dasher.cc/foto/24_056.jpg)
24mm at f5.6/1s
Oof, that lower left corner is really soft, almost as bad as the 35mm Per Inge tested.

Quote
Photos taken on ISO50, MLU and remote on top of a Gitzo G1500.
Unless you need the lowered sensitivity and can't compensate with shorter shutter times, ISO 100 probably yields better quality, since ISO 50 is a simulation of lower sensor gain.
Title: My primes not as sharp as zooms, huh?!?
Post by: Dasher on January 13, 2007, 06:29:10 pm
Hej Jani,

My Norwegian isn't that good (jeg snakker ikke Norsk), but I am visiting Norway in june for a few weeks so I can catch up a little   Hence my testing to see what I will take with me there.

I've heard that it may be an issue with older primes on DSLR sensors, that they are not as sharp at the edges. But I find this strange, and very dissapointing as I now have three nice primes that are not useable for me. I like to make panorama's and was using the primes for their extra sharpness on my 10D and the result when stitching. Now with the 5D I will be back with the 17-40 it seems. Not a bad thing, but I then wonder why I should keep the primes.

I will read the article, should pick up on some things (I'm dutch myself).
Title: My primes not as sharp as zooms, huh?!?
Post by: Shaula on January 13, 2007, 06:30:47 pm
I don't know that it would make any difference, but my understanding is that ISO 50 is a specialty setting only for use when 100 won't give you the available settings required to get the shot (like 3200), but does not in fact offer better performance.  Did you try the test at ISO 100?  I have not heard that the 17-40 outperforms the primes in sharpness in general usage (quite the opposite), but if that is your experience it raises an interesting some interesting questions.
Title: My primes not as sharp as zooms, huh?!?
Post by: Dasher on January 13, 2007, 06:37:17 pm
I tried the 50 this time as it sometimes gives more detail than the 100 setting. But even at 100 or 200, I get the same results.

I bought a 35/f2 last month for a dedicated pano lens. When I got it I thouht it may be nice to compare with the two L-zooms that I had (both share the 35mm setting). To my surprise the 35 was VERY fuzy in the corners, even at 8.0 when I had never seen this on my zooms. Kind of rendering the 35mm quite useless to me (I traded it in twice and finaly gave up and got a fisheye to play with).

This led me to test the other zooms, only to find out they all had the same thing: fuzy corners.


PS: My 50mm f1.8 II, yeah that $80 piece of plastic, does not have this problem. It's sharp from corner to corner. Same with the 100/2.8 and 200/2.8. So it does seem to be a wide-angle issue.
Title: My primes not as sharp as zooms, huh?!?
Post by: Craig Arnold on January 14, 2007, 03:23:09 am
It is an article of faith that primes are always and everywhere sharper, have better CA, etc. than zooms, in fact with many of the older prime designs compared to the new zooms designed with considerable computing power it is simply not the case.

To be fair it is more a case of new v old lens design. I doubt that you will find the same when comparing the 24-105 L against the new 50mm f1.2 L for example.

But it certainly doesn't surprise me that a new L zoom can outperform an old prime, it conforms with my expectations, experience and the MTF charts I have seen.

The reason I buy primes is for the wide apertures, not the sharpness, lack of CA, etc.
Title: My primes not as sharp as zooms, huh?!?
Post by: gochugogi on January 14, 2007, 02:41:06 pm
When I first bought the EF 24-105 4L IS USM I took test shots with my 5D and compared it against my EF 50 1.4 USM and 50 1.8 (MK I). AT 50 F4 I was shocked to find the zoom was both sharper but more contrasty than both primes (at infinity). True the primes have no light fall-off at F4, but the zoom was much better otherwise. I also compared it against my EF 50 2.5 CM. Now the 50 2.5 was about the same as the zoom, perhaps slightly better and, of course, suffered no light fall-off at F4. I sold both my 50 1.4 and 50 1.8, keeping the 50 2.5. The 50 2.5 is excellent even wide open, something I couldn't say for the other 2 50s.
Title: My primes not as sharp as zooms, huh?!?
Post by: Dasher on January 14, 2007, 04:34:16 pm
I just hung up a newspaper and made some testshots (wiped out the original pictures I posted in the progress). The primes are sharper than the zoom here, compared to in the field. I think Ik have a serious focusing problem with my 5D and wide-angle primes.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 14, 2007, 06:43:33 pm
You have to bear in mind that all lenses (with few exceptions) suffer resolution fall-off at the edges. All lenses (with few exceptions) are not as sharp at full aperture as they are when stopped down. Wide angle lenses in general suffer more from these factors than standard and telephoto lenses.

Resolution fall-off at the edges is much more apparent when using full frame 35mm. I got a shock when I first used the shift on my TS-E 24mm with the 5D. Resolution is unacceptable at the corners and edges. However, I did not have such problems using this lens with the 20D. I now have to ask myself if there's any advantage to using the TS-E 24mm with my 5D, for stitching purposes, if I have to crop out the fuzzy parts. I'll perhaps get a sharper image using this lens with my 20D.

You should also bear in mind that few fast lenses are sharp at full aperture, even in the centre. The 50/1.2, 50/1.4, 50/1.8 and 85/1.2 are all pretty poor at full aperture.
Title: My primes not as sharp as zooms, huh?!?
Post by: ErikKaffehr on January 16, 2007, 01:24:05 am
Hi!

I'd suggest that when we are striving for optimal sharpness we would put the lens on tripod and use with optimum aperture, for which 8.0 is a good guess. That would also compensate somewhat for focusing errors.

When shooting in low light a high aperture may come handy. Focusing will be highly critical, and the area within correct focus probably small. Some of the softness may be acceptable.

There are primes that are very sharp at full aperture, mostly L-designed telephotos and lenses of similar ilk.

That said I had a 50 mm lens once upon the time. It was probably a good one, but I actually never used it in the field. A 28-70 zoom was just much more comfortable and I could not seethe sharpness advantage of the prime in real pictures. This was in the time I used slide film.

Best regards

Erik

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You have to bear in mind that all lenses (with few exceptions) suffer resolution fall-off at the edges. All lenses (with few exceptions) are not as sharp at full aperture as they are when stopped down. Wide angle lenses in general suffer more from these factors than standard and telephoto lenses.

Resolution fall-off at the edges is much more apparent when using full frame 35mm. I got a shock when I first used the shift on my TS-E 24mm with the 5D. Resolution is unacceptable at the corners and edges. However, I did not have such problems using this lens with the 20D. I now have to ask myself if there's any advantage to using the TS-E 24mm with my 5D, for stitching purposes, if I have to crop out the fuzzy parts. I'll perhaps get a sharper image using this lens with my 20D.

You should also bear in mind that few fast lenses are sharp at full aperture, even in the centre. The 50/1.2, 50/1.4, 50/1.8 and 85/1.2 are all pretty poor at full aperture.
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Title: My primes not as sharp as zooms, huh?!?
Post by: Paul Kay on January 16, 2007, 06:03:34 am
"The 50/1.2, 50/1.4, 50/1.8 and 85/1.2 are all pretty poor at full aperture."

I read this a lot BUT they are fast and can be used where other lenses cannot - no zoom offer similar apertures. I use 24/1.4, 35/1.4 , 50/1.2 (just!) and 85/1.2 and wouldn't waste my money on them unless I needed to use them full open. Sure their performance may not be as good as at f/5.6~8 but then I can't shoot at f/5.6~8 ion the same conditions.

Secondly, zooms suffer from distortion - I've tried several but find that curved horizons (sea) are of no use to me and I don't want to always have to adjust during post processing. Sharpness is a useful and somewhat essential attribute but beyond an acceptable level is not the be all nor end all of lenses.

Lenses are a tool and the right one for the job depends on many factors - a bit like pixel count really. To get back to the original post, the real advantage of the 24/2.8 and 35/2 is weight - both are small and light (not so with the 20) but if you need sharper, heavier lenses then the zooms are potentially a better choice. Paradoxically I liked neither the 17~40 nor 24~105 as I found them to be adequate but not stellar performers and they were simply too slow!
Title: My primes not as sharp as zooms, huh?!?
Post by: Kirk Gittings on January 16, 2007, 11:36:37 am
Lenses should be judged against how well they do for their intended purpose. A 1.2 lens should perform well hand held at maximum aperture. Why buy it otherwise? Likewise a 24TS is a substitute for a view camera. It is designed to be used methodically on a tripod at its best aperture much like a VC. Mine performs exceptionally well at f/11 as does my 45TS. I would not consider using or testing these lenses wide open or using them hand held.
Title: My primes not as sharp as zooms, huh?!?
Post by: Paul Kay on January 16, 2007, 12:11:49 pm
Absolutely Kirk!

And for the record my fast lenses all produce saleable image wide open. I find them 'fit for purpose' and certainly not poor at full aperture. However as stated it is about what they are used for.

Perhaps I should also have commented that I do own a 35/2 Canon as well as a 1.4 and not its not as good in my experience but then it didn't cost 20% of the 1.4 either! And I don't think its as sharp as either the 17~40 or 24~105 but it is a lightweight little thing and for the use I put it to it works well enough. (If you are interested it shoots seaweeds well behind a flat port underwater, and its edge detail is further degraded by being stick behind a thick, flat piece of glass and viewing into relatively murky (British) water)! Lenses are tools.
Title: My primes not as sharp as zooms, huh?!?
Post by: Dasher on January 16, 2007, 01:15:25 pm
My purpose is to use them for panorama's. Off of a good tripod. Stiching sometimes gives little errors because the corners are a bit soft sometimes. I already had the 20mm before I got the 17-40, and I found the 24mm for a good price. It wasn't until I got the 35mm for dedicated panorama work, that I started to test the primes vs zooms.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 16, 2007, 09:43:34 pm
Quote
Lenses should be judged against how well they do for their intended purpose. A 1.2 lens should perform well hand held at maximum aperture. Why buy it otherwise? Likewise a 24TS is a substitute for a view camera. It is designed to be used methodically on a tripod at its best aperture much like a VC. Mine performs exceptionally well at f/11 as does my 45TS. I would not consider using or testing these lenses wide open or using them hand held.
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Yes, of course. We should not lose sight of the fact that lenses are tools. I also use my 24TS on a tripod and mostly at f11. However, since I discovered the poor edge performance when I started using this lens with my 5D, I'm beginning to find that my Sigma 15-30 is a more useful tool. After perspective correction in PS, I still get a wider shot than I could ever take with the 24TS.

Consider the follow architectural shot with uncorrected perspective; Sigma 15mm at f11.

[attachment=1564:attachment]

I wasn't sure if I could fix this in PS and still get a presentable (and improved) image. I think it's worked out okay, but I'm a bit concerned with the excessive degree of distortion in upper left corner.

[attachment=1565:attachment]

You're lucky your 24TS is sharp to the edges. I recall Jack Flesher mentioning that Canon had improved this lens since it first came out. Perhaps I should do a bit of in-store comparisons, if I can find a store that carries the lens in stock.  
Title: My primes not as sharp as zooms, huh?!?
Post by: Kirk Gittings on January 16, 2007, 11:42:46 pm
Ray that very well may be the case. Mine was just purchased in October from B&H which presumably has a rapid turnover. Also, at the urging of a very knowledgeable friend, I bought some Olympus PC lenses to use on the Canon. Reportedly these are some of the best performing PC lenses out there. The Canons were better by a long shot so I resold the Olympus lenses. I don't know what to say. Mine Canons are good.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 17, 2007, 03:34:46 am
Quote
Ray that very well may be the case. Mine was just purchased in October from B&H which presumably has a rapid turnover. Also, at the urging of a very knowledgeable friend, I bought some Olympus PC lenses to use on the Canon. Reportedly these are some of the best performing PC lenses out there. The Canons were better by a long shot so I resold the Olympus lenses. I don't know what to say. Mine Canons are good.
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Of course, Kirk, you have never specified whether you are using a full frame sensor or a cropped format, as I recall.

Looking through the images from my latest trip, I see that stitched 24TS images with the camera positioned vertically, fare much better. With camera vertical, the stitched aspect ratio is almost square. Most of all four sides are well away from the image circle circumference. It's only the corners that are then rather blurred.

With camera vertical, the resulting stitch is virtually double the file size of a single shot. One might be led to the opinion that such an image (with the 5D) has the over all resolution of a 25MB digital MF back.

The following example looks rather detailed to me. Perhaps as detailed (or more detailed) than any single shot from the sharpest 35mm (format) wide angle lens that money can buy.

Here's a jpeg of the full 70MB (8 bit) image, downsized of course.

[attachment=1568:attachment]

Here's a 100% crop of the centre (not downsized). It looks quite sharp to me, and of course this small crop is representative of a huge print size.

[attachment=1569:attachment]

The corners are quite blurred (believe me   ) but that disappears quite rapidly as one moves towards the centre of the edges, which are reasonably sharp.

I don't think I'll chuck this lens away just yet   .
Title: My primes not as sharp as zooms, huh?!?
Post by: Eric Myrvaagnes on January 17, 2007, 12:25:16 pm
Very impressive, Ray. I'd love to see the actual print. Bring one by if you are ever in the Boston area. I'll even take you to dinner to get a chance to see it.    

Eric
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 17, 2007, 07:13:11 pm
Thanks, Eric. You seem to be amongst the few who appreciate my attempts at photography   .

Not sure if I'll ever visit the USA. I've seen so much of America in Hollywood movies since the time I was a small boy, I don't feel the need to go there. If I do, I'll catch up with you of course   .
Title: My primes not as sharp as zooms, huh?!?
Post by: spotmeter on January 20, 2007, 07:04:37 pm
It is well known that Canon wide angle primes are not very good.  This is why so many Canon shooters buy Zeiss, Contax, Nikon and Olympus manual focus wide angle lenses and an adapter to use with their Canon body.

The worst of the Canon wide angles is my 24mm TS-E, which is soft at all apertures.  I sent it back to Canon, they replaced the focussing mechanism (which was not the problem) and pronounced it 'within specs'.  I use it now as a papeweight to keep papers from blowing off my desk.

I test all my manual focus lenses against my 17-40, which is exceptionally sharp, even in the corners, at f8 and f11.  The new Zeiss ZF are the sharpest wide angle lenses I have tested (I have the 50 and 35), and the Contax 21mm (designed by Zeiss) is also an exceptionally sharp lens throughout the field, as is the Contax 28mm.  I am looking forward to the new Zeiss 25mm.

I don't know why Canon can produce a zoom lens that is so much better than its primes.  Perhaps it is a later design.  If that is the case, we can hope that Canon comes out with some new, better-designed wide angle primes to take full advantage of their full frame sensors.
Title: My primes not as sharp as zooms, huh?!?
Post by: Paul Kay on January 21, 2007, 08:30:50 am
"It is well known that Canon wide angle primes are not very good."

Sorry to disagree but I think that this ought to say that is is "an internet promoted assertion that Canon wide-angle primes are not very good".

Some certainly are - I have a couple. Its true enough to say that some of their lenses are probably not that good - the 20/2.8 certainly has soft corners but others, such as my 24/1.4, are very usable indeed. My suspicion is that it is all too easy to find fault and broadcast it, and all too easy to forget that lenses are tools and are as good as they job they are being used for demands. In my experience it is rare for an image to be unacceptable due to the lens being used - far more are unacceptable due to the photographer making unwise choices which may or may not include the choice of lens. Having sold many thousands of images I have NEVER lost an image sale due to the image quality provided by the lens I was using - and this includes Canon wides.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 21, 2007, 10:37:03 pm
Quote
Sorry to disagree but I think that this ought to say that is is "an internet promoted assertion that Canon wide-angle primes are not very good".

Paul,
There's no smoke without fire. I think I've demonstrated that the 24TS with camera vertical can produce remarkably detailed images using shift for stitching purposes, way beyond what could be achieved with a single shot.

However, now that I've seen the results at the extreme edges, with camera horizontal (on the 5D), there's no way I'm going to bother using this lens in this way. If I need a stitched image with camera horizontal, I'll use my 20D with the 24TS.

I notice that Kirk Gittings has been very quiet on the issue of which camera he's using with his TS-E 24mm.

What I'd like to see is a comparison between a P25 with Digitar 24mm ultra wide, and 2 stitched 24TS images with the 5D, camera vertical. The image size and aspect ratio should be almost identical in both cases, but I suspect the Digitar is a much sharper lens than the 24TS, and of course it's a much more expensive lens.

Another issue that concerns me is the benefits of a centre filter. I notice that Schneider Optics offer a centre filter for their 24mm, that provides 2 stops variation between centre and edges. It seems to me that this is what's required for the Canon 24TS.

However, I don't think one can assume that raising the exposure at the edges will solve the resolution fall-off. It seems to me that some lenses have a vignetting problem at the edges as well as resolution fall-off. Other lenses, like the Digitar 24mm, might suffer from peripheral light fall-off but not peripheral resolution fall-off.

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In my experience it is rare for an image to be unacceptable due to the lens being used - far more are unacceptable due to the photographer making unwise choices which may or may not include the choice of lens. Having sold many thousands of images I have NEVER lost an image sale due to the image quality provided by the lens I was using - and this includes Canon wides.

Well, of course, this gets us back to the very old issue, that's been debated many times on this forum, of whether it's the equipment or the photographer that 'makes' the picture.

The answer is quite clear. It's both. I've never yet come across an instance of a photographer who has been able to take a photo without using any equipment (good or bad), but I have come across instances of photos being taken by equipment without a photographer. The Mars Rover is an example   .
Title: My primes not as sharp as zooms, huh?!?
Post by: Ronny Nilsen on January 22, 2007, 03:41:56 am
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However, now that I've seen the results at the extreme edges, with camera horizontal (on the 5D), there's no way I'm going to bother using this lens in this way. If I need a stitched image with camera horizontal, I'll use my 20D with the 24TS.
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That's really not that suprising is it? On a 5D with full horisontal shift you are using an image circle dia. of 62.55 mm. (you get an 23.9 x 57.8 "sensor") The spec for the lens says that it have an image circle dia. 58.6mm. With the 20D you are only using an 46.95mm image circle dia. Doing a vertical shift with a 5D uses an images circel of 58.21 mm and should be ok acoording to the spec.

What is suprising is that the spec for the 90TS and 45TS states the same image circle (58.6mm) but my  lenses are sharp to the corner on my 5D letting me use an image circle dia. of 62.55 mm. So a 45TS on 5D migth be a better option than a 24TS on a 20D? Or just limit horisontal shit to +/- 9mm?
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 22, 2007, 06:23:36 am
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That's really not that suprising is it? On a 5D with full horisontal shift you are using an image circle dia. of 62.55 mm. (you get an 23.9 x 57.8 "sensor") The spec for the lens says that it have an image circle dia. 58.6mm. With the 20D you are only using an 46.95mm image circle dia. Doing a vertical shift with a 5D uses an images circel of 58.21 mm and should be ok acoording to the spec.

What is suprising is that the spec for the 90TS and 45TS states the same image circle (58.6mm) but my  lenses are sharp to the corner on my 5D letting me use an image circle dia. of 62.55 mm. So a 45TS on 5D migth be a better option than a 24TS on a 20D? Or just limit horisontal shit to +/- 9mm?
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Well, yes, it is surprising. The primary use of the shift is for perspective control. I could be photographing a skyscraper or cathedral with camera in vertical position. If I were to use the full 11mm movement, the top of the cathedral would be unacceptably dark and degraded.

I've thought of getting the 45TS, but I ask myself if I would use it enough to justify the expense. These are also heavy lenses. On my recent trip to Nepal and Cambodia, I left behind my TS-E 90 because of weight considerations. I decided the wider lens would be more useful. Would I want to carry a 45TS as well as the much lighter 50/1.4?
Title: My primes not as sharp as zooms, huh?!?
Post by: Ronny Nilsen on January 22, 2007, 07:51:33 am
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Well, yes, it is surprising. The primary use of the shift is for perspective control. I could be photographing a skyscraper or cathedral with camera in vertical position. If I were to use the full 11mm movement, the top of the cathedral would be unacceptably dark and degraded.
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It would of course have been better if the lens had an image circle of 63mm, but it does not, it only have an image circle large enough to have the fuill +/- 11mm of vertical shift, and only +/- 9mm horizontal shift. That's in the spec of the lens and should not be a suprise.  

Just as you dont twist the focus ring to infinity without checking if that is the right focusing distance, you should also check the shift when doing horizontal shift, but you know that.  

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I've thought of getting the 45TS, but I ask myself if I would use it enough to justify the expense. These are also heavy lenses. On my recent trip to Nepal and Cambodia, I left behind my TS-E 90 because of weight considerations. I decided the wider lens would be more useful. Would I want to carry a 45TS as well as the much lighter 50/1.4?
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I guess that depends on personal preferences and what you are shooting, but I would prefer the 45 over th 50.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 22, 2007, 12:13:12 pm
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It would of course have been better if the lens had an image circle of 63mm, but it does not...[a href=\"index.php?act=findpost&pid=96964\"][{POST_SNAPBACK}][/a]

This is simply not true, Ronnynil. If the image circle was not 63mm, I could not possibly get any image at all in the corners   .

Of course, I understand that Canon might be saying indirectly, with their spec of 58.6mm, that this is in their opinion the maximum image circle for acceptable quality. In other words, 'don't use the full shift with our tilt and shift lens'.

I don't see any such warning on the packaging, however.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ronny Nilsen on January 22, 2007, 02:40:18 pm
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This is simply not true, Ronnynil. If the image circle was not 63mm, I could not possibly get any image at all in the corners   .
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I guess you are talking about the circle of illumination. Not the the image circle of a lens that are the circle of sharp definition WITHIN the circle of illumination? But english is not my native language so I may miss the finer points of your language here.  

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Of course, I understand that Canon might be saying indirectly, with their spec of 58.6mm, that this is in their opinion the maximum image circle for acceptable quality. In other words, 'don't use the full shift with our tilt and shift lens'.

I don't see any such warning on the packaging, however.
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My manual for the TS lenses page 48 warns about this (Page title Precautions!):

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2) When combining tilt and shift function with the TS-E 24mm f/3.5L lens, setting amount s indicated in red may cause shading.
3) When using the TS-E 24mm f/3.5L, shifting more than 8mm may cause shading on the long edges or in corners of the picture. Be especially carful when using a camera other than the EOS-1, EOS-1N.

So Canon states clearly in both the spec and the manual that you are using the lens outside the image area that they consider acceptable. They have even marked the shifting on the lens that can cause shading in red, not the gray used for the rest of the shifting range.

So I say again; your results should not be a suprise.  
Title: My primes not as sharp as zooms, huh?!?
Post by: RedRebel on January 22, 2007, 04:08:19 pm
I also have a 35mm/f2 and bought it while I had a 350D. Then I already noticed that it was about as sharp as my 17-85-IS when both used wide open and at f2.0 it's horrible. Then the 35mm/f2 also suffered from focussing issues, the lens was designed for film camera's and not for 1.6 crop bodies. The shop where I purchased it (Foto Konijnenberg) confirmed this.

When I purchased my 5D I noticed that the focussing issues with the 35/f2 were solved, but its not as sharp as my 24-105L.

Someone mentioned that "old design" primes are not as sharp/good as recent zoom lenses, and I think that's true. I think that you realy have to be carefull when selecting a very fast prime lens if you have very high demands in terms of lens speed and sharpnes. The 35/f2 also suffers from lots of CA and flare (contrast drop). I never use my copy of the 35/f2, it's a waste of money. The new 50mm/f1.2L is a great lens I think, but it's price is not justified for me.
Title: My primes not as sharp as zooms, huh?!?
Post by: Kirk Gittings on January 22, 2007, 04:16:32 pm
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I notice that Kirk Gittings has been very quiet on the issue of which camera he's using with his TS-E 24mm.

Sorry I missed this. I am buried with shoots.

A 5D (which will likely become my backup camera when I see what is available in the spring).
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 22, 2007, 09:22:50 pm
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I guess you are talking about the circle of illumination. Not the the image circle of a lens that are the circle of sharp definition WITHIN the circle of illumination? But english is not my native language so I may miss the finer points of your language here. 

Your English is fine. Most lenses suffer from both vignetting and resolution fall-off towards the edges even though it might not always be particularly noticeable. It seems that image quality just gets progressively worse away from the centre. There's no cut-off point like, 'now the image is good. Now it's not good'. The Photodo MTF charts tell the story. Wide angle lenses are generally much worse in this respect, but sometimes telephoto mirror lenses are particularly bad. The Sigma 14mm prime is particularly poor towards the edges.

This gradual deterioration of lens performance towards the corners is what makes cropped format APS-C cameras so appealing. You don't have to worry about such factors whatever the lens.

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So Canon states clearly in both the spec and the manual that you are using the lens outside the image area that they consider acceptable. They have even marked the shifting on the lens that can cause shading in red, not the gray used for the rest of the shifting range.

Okay! You got me there   . I should have paid more attention to the manual and that little red line on the lens. I guess Canon are covering their backsides. Anyway, I bought the lens when I was using the D60 and 20D. There would seem to be little advantage (for my purposes) using it with the 5D if I have to crop the image to something approaching the FoV of the 20D.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 22, 2007, 09:29:50 pm
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Sorry I missed this. I am buried with shoots.

A 5D (which will likely become my backup camera when I see what is available in the spring).
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Kirk,
Sorry to labour the point. Are you paying attention to those red warning lines on the 24TS, or is your lens so good at the edges you can safely ingnore them?
Title: My primes not as sharp as zooms, huh?!?
Post by: Kirk Gittings on January 22, 2007, 10:43:19 pm
Yes Ray, If there is important detail in the corner(s) in the shift direction. Understand we are almost always shooting tethered and it is easy to check this in the field.
Title: My primes not as sharp as zooms, huh?!?
Post by: Paul Kay on January 23, 2007, 03:23:52 am
"There's no smoke without fire. I think I've demonstrated that the 24TS with camera vertical can produce remarkably detailed images using shift for stitching purposes, way beyond what could be achieved with a single shot."

Absolutely! A good discussion which demonstrates the value of a forum like this. What I was trying to get at is that a sweeping statement regarding Canon prime wide-angles being poor is simply a potential internet myth in the making and a gross oversimplification of the technical issues involved. Take my 24/1.4 as an example - it works pretty well for me and I would be interested in knowing what other lenses exist to allow me to shoot wide open with this field of view on full frame? My ponit being that there is nothing to really compare it with and it delivers perfectly acceptable results.

Many people read information on the internet and if a statement is made often enough they may believe it whether it is truly accurate or otherwise. I think that it is important to qualify such statements and use a discussion forum as in this thread, to actually discuss issues and hopefully to learn accurately from such discussions.

As a specialist in underwater photography, I can say that Nikon still predominates probably due to the legacy of the Nikonos 5 and the perceived need for ttl flash control which remains an ingrained and perpetuated idea even today - although so much has changed that choices are far more wide-open now.

So sorry if I sounded off, but perhaps my point requires further discussion (elsewhere if not here).
Title: My primes not as sharp as zooms, huh?!?
Post by: Ronny Nilsen on January 23, 2007, 06:46:38 am
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Anyway, I bought the lens when I was using the D60 and 20D. There would seem to be little advantage (for my purposes) using it with the 5D if I have to crop the image to something approaching the FoV of the 20D.
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The advantage of the TS-24 on a 5D is that you can get almost the same resolution (12.8mpx) with one shot as you get with a stitched 20D image (16.3mpx) from the same lens. And the 5D will then also only use the best part of the image circle (more than the 20D).

But the  20D will give a 1:3 panorama if thats what you want.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 23, 2007, 09:35:18 am
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The advantage of the TS-24 on a 5D is that you can get almost the same resolution (12.8mpx) with one shot as you get with a stitched 20D image (16.3mpx) from the same lens. And the 5D will then also only use the best part of the image circle (more than the 20D).

But the  20D will give a 1:3 panorama if thats what you want.
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With 20D mounted vertically, shifting fully from one side to the other (completley ignoring the red lines   ), taking 3 shots then stitching, you get roughly the equivalent of a single shot with the 5D horizontal; almost the same aspect ratio and same FoV, but a much higher resolution, about 19 megapixels.
Title: My primes not as sharp as zooms, huh?!?
Post by: jani on January 25, 2007, 07:46:57 am
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With 20D mounted vertically, shifting fully from one side to the other (completley ignoring the red lines   ), taking 3 shots then stitching, you get roughly the equivalent of a single shot with the 5D horizontal; almost the same aspect ratio and same FoV, but a much higher resolution, about 19 megapixels.
I'm not sure that I'd sign any paper that said ca. 19 megapixels is a "much higher resolution" than ca. 13, it's only just above a 20% angular resolution increase.

Even with a 400D, you'd get just about a third more angular resolution.

If the 5D gave you a 18x12 print in usable quality, the 20D triple-stitched might then give you a 21.5x14.5, and the 400D a 24x16.

I can see how it might be worth the trouble if you need that extra resolution, but why not just do a regular double-stitch with the 5D, also ignoring the red lines? Am I missing something?
Title: My primes not as sharp as zooms, huh?!?
Post by: Ronny Nilsen on January 25, 2007, 08:14:13 am
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I can see how it might be worth the trouble if you need that extra resolution, but why not just do a regular double-stitch with the 5D, also ignoring the red lines? Am I missing something?
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Becuse ignoring the red lines on TS24 will push the larger 5D sensor into the bad parts of the image circle.

But only using +/- 8mm shift on the 5D will give you a 18.4 mpx 1:2.1 image or a 21.2 mpx 1:1.1 image, which still is better than the 20D 16.3 mpx and 20.3 images. On the TS45 and TS90 you can do the full shift on a 5D with very god results.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 25, 2007, 10:17:15 am
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But only using +/- 8mm shift on the 5D will give you a 18.4 mpx 1:2.1 image or a 21.2 mpx 1:1.1 image, which still is better than the 20D 16.3 mpx and 20.3 images.[a href=\"index.php?act=findpost&pid=97465\"][{POST_SNAPBACK}][/a]

It's not better in the corners though. This is a lens with a reasonably flat MTF response (for a wide angle lens) but only within the normal image circle that applies to 35mm, ie. up to 21mm from the centre. Any shift at all (with FF 35mm)pushes the lens into noticeable degradation in the corners. With the 20D, you can get a 20mp image (perhaps 19 after cropping) which is acceptably sharp and free of vignetting, from corner to corner.
Title: My primes not as sharp as zooms, huh?!?
Post by: Jonathan Wienke on January 25, 2007, 11:12:58 am
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I'm not sure that I'd sign any paper that said ca. 19 megapixels is a "much higher resolution" than ca. 13, it's only just above a 20% angular resolution increase.

Even with a 400D, you'd get just about a third more angular resolution.

...

Am I missing something?

Yes, the fact that angular resolution squared is how you calculate overall resolution. Doubling angular resolution quadruples image detail. As long as per-pixel image quality is comparable between the 13MP and 19MP images, the 19MP will look significantly better.
Title: My primes not as sharp as zooms, huh?!?
Post by: jani on January 25, 2007, 01:50:39 pm
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Yes, the fact that angular resolution squared is how you calculate overall resolution.
No, I did not miss that.

But this kind of "overall resolution" is not a term used in any other context.

With printers, for instance, we don't speak of 90,000 DPI squared as the "overall resolution", and since the target is -- hopefully -- print, speaking of an "overall resolution" on a different kind of scale is useless.

We don't even speak of monitor resolution as 10,000 PPI squared.

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Doubling angular resolution quadruples image detail. As long as per-pixel image quality is comparable between the 13MP and 19MP images, the 19MP will look significantly better.
But only up to a print that's 20% larger in any direction.

I'm not sure that's "significantly better".


But I did miss the fact that "redlining" the 5D was worse than "redlining" the 20D, so thanks to Ronny and Ray for making that clear.
Title: My primes not as sharp as zooms, huh?!?
Post by: Jonathan Wienke on January 25, 2007, 02:42:48 pm
With devices that have equal resolutions or DPI in both direction, yes, it is common to not repeat the equal vertical and horizontal numbers, but when the numbers are not equal, it is indeed common to give both. For example, the Epson R1800 has a resolution of 5760x1440DPI. If you increase image detail only on one axis, resolution increases linearly, proportional to the increase on the single axis. But when the resolution on both axes change equally, the overall resolution is the square of the resolution on either axis. 19MP is a significant, visually obvious improvement over 13MP when individual pixel quality is similar in both images.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 25, 2007, 07:06:51 pm
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19MP is a significant, visually obvious improvement over 13MP when individual pixel quality is similar in both images.
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I imagine so. When I'm out in the field next with an interesting static subject to shoot, I'll try and remember to take a single 5D shot with the 24TS, camera horizontal, and 3x20D shots from the same position, camera vertical, using shift to its maximum, and compare images.

The aspect ratios will not be exactly the same. The 20D stitched images should have marginally less height. However, depending on the required cropping, the resolution differences should be fairly similar to those when taking a single shot with each camera with identical lens and f stop, then cropping the 5D image to the same FoV as the 20D image.

However, I accept that such differences in resolution are probably not significant on smallish prints. But my printer is capable of producing a 24"x36" print from a single 35mm frame. The less interpolation the better.  
Title: My primes not as sharp as zooms, huh?!?
Post by: jani on January 26, 2007, 05:23:52 am
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With devices that have equal resolutions or DPI in both direction, yes, it is common to not repeat the equal vertical and horizontal numbers, but when the numbers are not equal, it is indeed common to give both. For example, the Epson R1800 has a resolution of 5760x1440DPI. If you increase image detail only on one axis, resolution increases linearly, proportional to the increase on the single axis. But when the resolution on both axes change equally, the overall resolution is the square of the resolution on either axis.
No, that's not the "resolution", that's the total amount of "image information", if you will.

You won't resolve twice as much detail if you double what you call "resolution", you'll have to quadruple your "resolution" to get double the detail.
Title: My primes not as sharp as zooms, huh?!?
Post by: jani on January 26, 2007, 05:24:51 am
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However, I accept that such differences in resolution are probably not significant on smallish prints. But my printer is capable of producing a 24"x36" print from a single 35mm frame. The less interpolation the better. 
I'd hesitate to call prints below 24x36 "smallish", though. 24x36 is big.
Title: My primes not as sharp as zooms, huh?!?
Post by: Ray on January 26, 2007, 08:02:39 am
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I'd hesitate to call prints below 24x36 "smallish", though. 24x36 is big.
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I like my prints big. Standard 8x10" prints only became popular because of the limitations of the ubiquitous miniature 35mm film camera that was no good for anything bigger   .