Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: ScubaZ on May 17, 2012, 11:32:45 pm
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Can anyone point me to a chart showing which aperture is the sharpest for Hasselblad HC lenses when focuses at infinity? Specifically the 28, 35-90 and 150N.
I'm not a techie and don't have much knowledge of MTF charts and the like. Just want to know mostly for landscape what aperture to use if available light/shutter speed is not a concern. I typically just assume somewhere around f11, but would be nice to have something more scientific/tested.
Thanks.
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Hi,
For almost any lens of decent quality f/8 is the best aperture. The reason is that aberration are minimized and diffraction does not limit performance. You can stop down to f/16 without much loss of sharpness and diffraction is benign to sharpening, so you can improve the image a lot with deconvolution type sharpening.
Can anyone point me to a chart showing which aperture is the sharpest for Hasselblad HC lenses when focuses at infinity? Specifically the 28, 35-90 and 150N.
I'm not a techie and don't have much knowledge of MTF charts and the like. Just want to know mostly for landscape what aperture to use if available light/shutter speed is not a concern. I typically just assume somewhere around f11, but would be nice to have something more scientific/tested.
Thanks.
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For almost any lens of decent quality f/8 is the best aperture. The reason is that aberration are minimized and diffraction does not limit performance. You can stop down to f/16 without much loss of sharpness and diffraction is benign to sharpening, so you can improve the image a lot with deconvolution type sharpening.
This tends to be a lot more true for wider glass.
Most high quality tele designs are near optimal at full aperture or at most one stop down.
Cheers,
Bernard
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This tends to be a lot more true for wider glass.
Most high quality tele designs are near optimal at full aperture or at most one stop down.
Cheers,
Bernard
Hi Bernard!
Can you show me one single tele-lens that is sharpest at full aperture?
I have tested many, and all I have seen yet are sharper at one or two stops down.
Henrik
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Hi Bernard!
Can you show me one single tele-lens that is sharpest at full aperture?
I have tested many, and all I have seen yet are sharper at one or two stops down.
Henrik
I'm not Bernard, but the Zeiss 250mm f5.6 Hasselblad 'C' lens had its best MTF etc at full aperture.
John
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Can you show me one single tele-lens that is sharpest at full aperture?
I have tested many, and all I have seen yet are sharper at one or two stops down.
I did write full aperture or one stop down, but some that are optimal at full aperture are:
- Leica 180 f2.8 APO
- Leica 280 f4.0 APO
As far as being optimal one stop down, some examples are seemingly:
- Nikon 300 f2.8 VRII (it is already the case on the V1 that I own), Nikon 400 f2.8 VR. There are few reviews of these lenses and factual data, but Thom is pretty clear about the performance wide open: http://www.bythom.com/nikkor-400mm-f28-lens-review.htm
- The equivalent Canon super tele lenses are supposed to be even better.
Anyway, the point is that f8 is often not the best aperture for tele lenses.
Cheers,
Bernard
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I did write full aperture or one stop down, but some that are optimal at full aperture are:
- Leica 180 f2.8 APO
- Leica 280 f4.0 APO
As far as being optimal one stop down, some examples are seemingly:
- Nikon 300 f2.8 VRII (it is already the case on the V1 that I own), Nikon 400 f2.8 VR. There are few reviews of these lenses and factual data, but Thom is pretty clear about the performance wide open: http://www.bythom.com/nikkor-400mm-f28-lens-review.htm
- The equivalent Canon super tele lenses are supposed to be even better.
Anyway, the point is that f8 is often not the best aperture for tele lenses.
Cheers,
Bernard
Bernard -
The Nikkor 2.8/180mm autofocus (my only af lens) is pretty hot wide open. I wouldn't hesitate to shoot girls with it at f 2.8.
I tried a series of exposures with it when I first received it: Gitzo-mounted, shots of the back of a white plastic garden chair with those diamond cutouts on the back and though closing down a couple of stops gave the impression of sharper results, it was very difficult indeed to be certain that what might be a crisper image wasn't simply due to a greated depth of field covering a further set of diamond shapes further into the shape of the curvature of the back.
Rob C
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I'm not Bernard, but the Zeiss 250mm f5.6 Hasselblad 'C' lens had its best MTF etc at full aperture.
John
Not really:
http://applications.zeiss.com/C12578620052CA69/0/5536FF3301189C7AC12578650041A5DB/$file/sonnar5-6_250mm_cfi_101137_e.pdf
Needs to be pasted as the system seems to think this link is too long.
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I did write full aperture or one stop down, but some that are optimal at full aperture are:
- Leica 180 f2.8 APO
- Leica 280 f4.0 APO
As far as being optimal one stop down, some examples are seemingly:
- Nikon 300 f2.8 VRII (it is already the case on the V1 that I own), Nikon 400 f2.8 VR. There are few reviews of these lenses and factual data, but Thom is pretty clear about the performance wide open: http://www.bythom.com/nikkor-400mm-f28-lens-review.htm
- The equivalent Canon super tele lenses are supposed to be even better.
The 180 is better stopped down:
http://en.leica-camera.com/assets/file/download.php?filename=file_1865.pdf
The 280 looks extremely impressive fully open. I think the Leica-lenses are very spesial in this way.
I have never used any of these lenses, but I would love to in the future after reading these MTF-charts :)
Henrik
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I stand corrected... but the 180 f2.8 APO is nonetheless pretty darn impressive wide open on the D800! It should still perform well on the 72 mp D1000 in 10 years. :)
I'll need a few more days until I can provide first hand comments about the 280mm f4.
Cheers,
Bernard
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Used as a high-magnification telescope, my Mamiya 200/2.8 APO peaks at f4. The resolution of detail, on the Moon or Jupiter for example, is equally good at f2.8, but the contrast (hence the MTF) is a bit lower.
At f4 it shows a really nice clean Airy disk.
At f5.6, the Airy disk is visibly larger, due to diffraction, and of course dimmer. And so on, down to f22. It's really fun to watch the Airy diffraction versus f-stop progression.You can't do that on a regular telescope - there's no aperture iris.
So what I usually do is use f4 for viewing the bright stuff where light is a given and contrast is needed instead (Moon, planets, double stars etc.), and f2.8 where maximum light grasp is best for sweeping the faint deep sky stuff, RFT style.
If I had the 300/2.8, that would be even better. 50% higher angular resolution at the same f-stop, and 125% more light grasp.
I know some of you guys have the 300/2.8, but you waste it by only taking photos through it :P
Ray
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Hi Bernard!
Can you show me one single tele-lens that is sharpest at full aperture?
I have tested many, and all I have seen yet are sharper at one or two stops down.
Henrik
I can think of two -
1. The Zeiss 250/5.6, where years ago in a promotional flyer, Hasselblad stated that sharpness was not improved by stopping down.
2. The Mamiya RZ 350/5.6 APO. Mamiya also stated the same thing in their promotions of this lens years ago.
By "years ago," I refer to film days in the 1990's.
Disclaimer - I'm a user, not a tester, so I go pretty much by what the manufacturers say in examples like these. And having owned and used both lenses, I was not unpleased with them wide open.
Oftentimes, we (or at least I) mis-judge "sharpness" for extended DOF, so images with greater DOF may often appear sharper.
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"I can think of two -
1. The Zeiss 250/5.6, where years ago in a promotional flyer, Hasselblad stated that sharpness was not improved by stopping down.
2. The Mamiya RZ 350/5.6 APO. Mamiya also stated the same thing in their promotions of this lens years ago."
Though I'm no lens tester either, these two also come to my mind...
Kornelius Fleischer/Mueller, marketing manager for Zeiss some years ago, a scientific photographer by background, said something similar on photo.net from his tests of the 250 SA for Hasselblad that the sharpness exceeded 250lppm in the centre (his film resolution limit), stopping down only serving to increase the depth of field.
I also ran across the MTF charts for some of the Mamiya RZ lenses some time ago and noticed something very strange for the 350 APO: its wide open measurements were even better than stopped down! How do the boffins explain that?
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Can anyone point me to a chart showing which aperture is the sharpest for Hasselblad HC lenses when focuses at infinity? Specifically the 28, 35-90 and 150N.
I'm not a techie and don't have much knowledge of MTF charts and the like. Just want to know mostly for landscape what aperture to use if available light/shutter speed is not a concern. I typically just assume somewhere around f11, but would be nice to have something more scientific/tested.
Thanks.
Have you ever considered running your own tests? If "infinity" is your primary concern, find a subject outdoors, focus on infinity, and take a shot at each full aperture with the appropriate shutter speed. Pick out the best 2-3 apertures, then take more at those apertures incorporating 1/2 or 1/3 stop intervals inbetween. You might find that some are indistinguishable from others, but ultimately you'll have your information first hand, with your particular lens. But you are on the right track. Most f2.8 lenses seem to perform best @ 5.6-8, while f4 lenses shine @ 8-11. I use the 35-90 zoom, and choose f8-f11 whenever possible, but have shot @ f22 for needed DOF, and cannot eyeball any sharpness differences in prints upwards to 24x32".
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Hi,
Any really good lens will perform best at aperture f/8 or larger. A lens that achieves best performance at f/11 is always a worse lens than one that achieves best at f/5.6. A lens that peaks at f/4 is better than one that peaks at f/5.6.
The reason for this is that diffraction increases with stopping down while uncorrected aberrations go down. Where diffraction meets aberrations the lens is diffraction limited. So optimum aperture is always when diffraction limit sets in.
Hint: the lens vendors normally publish two set of MTF curves one at full opening and one at optimal aperture, that is surprisingly often f/8. So just check the apertures that Hasselblad uses for the MTF charts.
This is good info: http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
This page illustrates the effects of diffraction (left column). It was shot with a macro lens on a 16MP APS-C camera. Results would be similar for any lens, once diffraction limit is reached.
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/49-dof-in-digital-pictures?start=1 (left column shows effects of diffraction)
Best regards
Erik
Have you ever considered running your own tests? If "infinity" is your primary concern, find a subject outdoors, focus on infinity, and take a shot at each full aperture with the appropriate shutter speed. Pick out the best 2-3 apertures, then take more at those apertures incorporating 1/2 or 1/3 stop intervals inbetween. You might find that some are indistinguishable from others, but ultimately you'll have your information first hand, with your particular lens. But you are on the right track. Most f2.8 lenses seem to perform best @ 5.6-8, while f4 lenses shine @ 8-11. I use the 35-90 zoom, and choose f8-f11 whenever possible, but have shot @ f22 for needed DOF, and cannot eyeball any sharpness differences in prints upwards to 24x32".
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Personally, I chose the best aperture for the image, not the MTF. I also believe using lenses for most things on Earth at something other than infinity. Crazy idea, I know, but those two little secrets really improve your photography, although they may lower your test target scores.
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I also believe using lenses for most things on Earth at something other than infinity. Crazy idea, I know ...
So true.
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Hi,
Most lenses are corrected for infinity, so they may perform worse at close distances. This is one area where the HC lenses perform better than the older Zeiss lenses. In practice it takes a floating element to achieve optimal image quality at both far and close focus. Normally a subject distance 100 times focal length would be seen as infinity, so on a 50 mm lens 5 meter count as infinity. In studio photography often much shorter distances may be used, so near field correction may matter a lot.
Lets put it this way: If you care about buying the best camera with the best lens and put it on a stable tripod use mirror lockup and focus by live view you should also mind optimal aperture. Stopping down a bit to far may loose quite a lot of the resolution. On the other hand, if subject is out of focus optimal aperture will not help.
Best regards
Erik
So true.
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Lets put it this way: If you care about buying the best camera with the best lens and put it on a stable tripod use mirror lockup and focus by live view you should also mind optimal aperture. Stopping down a bit to far may loose quite a lot of the resolution. On the other hand, if subject is out of focus optimal aperture will not help.
Best regards
Erik
If photography is simply an object lesson in resolving power, then that would be true. But for me, it is a creative medium used to make an image. My cameras are here to serve me and my vision, not to replicate MTF plots, which seems to be a very strange concept in photography today.
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Can anyone point me to a chart showing which aperture is the sharpest for Hasselblad HC lenses when focuses at infinity? Specifically the 28, 35-90 and 150N.
I'm not a techie and don't have much knowledge of MTF charts and the like. Just want to know mostly for landscape what aperture to use if available light/shutter speed is not a concern. I typically just assume somewhere around f11, but would be nice to have something more scientific/tested.
Thanks.
Scuba -
A couple years back I did some landscape comparison tests between Hasselblad HC 80mm and Phase One/Mamiya 80mm D lenses. I found the Hasselblad had a slight edge wide open and the Phase/Mamiya nicked it after f11. This result seemed duplicated for the equivalent 120mm lenses (although this testing was at macro distance). For Landscape I would say shoot the HC lenses between f8 - f11 for best results (in general). Your own testing and results will confirm if this is right for you. For the most part shooting wide open isn't going to be an advantage for a landscape shooter anyway - even if wide open was the sharpest aperture.
Steve Hendrix
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Sharpness in one thin plane is pretty worthless unless you want this effect. Otherwise f11 or f16 is perfect for MF photography. Sharp enough with sufficient d.o.f.
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Hi,
The original poster asked about optimum aperture.
The other point is that anyone buying high quality equipment may be interested in extracting best image quality from it. Best image quality can only be achieved by careful work.
Another way to see it is that if you stop down an MF camera to f/16 you may end up with less resolution than with f/8 on a much cheaper DSLR.
Best regards
Erik
If photography is simply an object lesson in resolving power, then that would be true. But for me, it is a creative medium used to make an image. My cameras are here to serve me and my vision, not to replicate MTF plots, which seems to be a very strange concept in photography today.
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Sharpness in one thin plane is pretty worthless unless you want this effect. Otherwise f11 or f16 is perfect for MF photography. Sharp enough with sufficient d.o.f.
Not everybody is shooting landscapes, just saying...
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Hi,
The original poster asked about optimum aperture.
The other point is that anyone buying high quality equipment may be interested in extracting best image quality from it. Best image quality can only be achieved by careful work.
Another way to see it is that if you stop down an MF camera to f/16 you may end up with less resolution than with f/8 on a much cheaper DSLR.
Best regards
Erik
Optimum for what? Best image quality for what? MTF? How about the background?
So, it still come down to whether you think photography is an object lesson in resolving power, as you seem to believe. Or whether the image itself is the point of photography where how you control the camera and and other factors are important in image quality such as depth of field, viewing distance, etc. Personally, I take a systemic view in photography where the process is in service of the photographer and his/her judgement that best interprets the object. The other point is the "best" aperture in regards to resolving power will not even be noticed in comparison to "worse" apertures under normal viewing conditions. What will be more important is whether the view perceives the image to be sharp, which is not the same as having the highest resolving power.
BTW, I have shot my camera at f/22 and made 36" test prints. I am still getting more detail and sharpness than generic DSLR at f/8. But if the resolving power is both the same, but greater than the ability of the viewer, who cares. You seem to be saying that 100% monitor view is some kind of absolute reference to image quality. Well, sensor size and pixel resolution is going to really skew that view.
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Lets put it this way: If you care about buying the best camera with the best lens and put it on a stable tripod use mirror lockup and focus by live view you should also mind optimal aperture. Stopping down a bit to far may loose quite a lot of the resolution. On the other hand, if subject is out of focus optimal aperture will not help.
This is exactly what I'm concerned with, stopping down too far. If I focus is at infinity, I understand the depth of field and agree with the other posters thats a matter of creativity, but where I decide I want everything in the frame as sharp as possible I would assume as you have suggested that shooting at f22 with a slower shutter speed likely is not going to get me as good a results in that particular situation as shooting at f8 or f11.
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This is exactly what I'm concerned with, stopping down too far. If I focus is at infinity, I understand the depth of field and agree with the other posters thats a matter of creativity, but where I decide I want everything in the frame as sharp as possible I would assume as you have suggested that shooting at f22 with a slower shutter speed likely is not going to get me as good a results in that particular situation as shooting at f8 or f11.
You could actually get a better result at f/22 because what you need in the image will have a higher resolution, not just some of it. Why don't you actually try shooting at different apertures and print out the results. Experience is the best teacher. Saying x is the sharpest aperture is the photographic equivalent of painting by numbers.
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If photography is simply an object lesson in resolving power, then that would be true. But for me, it is a creative medium used to make an image. My cameras are here to serve me and my vision, not to replicate MTF plots, which seems to be a very strange concept in photography today.
You are missing the point. Because photography is a creative medium it does not mean that knowing how to achieve the highest possible performance that ones tools are capable of is necessarily at odds with this creativity.
The high level of technical experience and knowledge of members of this forum is highly impressive and appreciated as far as I am concerned. And this coming from a guy who has frequently used zone plates, which use diffraction itself to resolve the image - AND likes to know if I want to capture some texture on a wall behind a subject what the best aperture choice would be.
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You are missing the point. Because photography is a creative medium it does not mean that knowing how to achieve the highest possible performance that ones tools are capable of is necessarily at odds with this creativity.
The high level of technical experience and knowledge of members of this forum is highly impressive and appreciated as far as I am concerned. And this coming from a guy who has frequently used zone plates, which use diffraction itself to resolve the image - AND likes to know if I want to capture some texture on a wall behind a subject what the best aperture choice would be.
??? I am missing the point?
The point of technical knowledge is just not to give an easy answer to achieve one thing, in this case the highest MTF, but to tell you how photography works so you can function in your medium and create the best result for yourself and your image. Everyone wants to be told what to do because that is easy--this is what the OP wants. Well, photography is not easy and you need to learn to control your medium. "F/11 and be there" is not control.
And you really can see now one really understands the medium. No one has brought up how the image will be perceived by a viewer. Sharpness is more important in giving the perception a photograph is detailed than resolving power. Yes, there are many experts here. I happen to be one of them--as Erik is. I am not advocating the wishy-washy idea that photography is a creative art and you should just let it all hang out and technique is irrelevant. I just don't believe in a formalistic approach to technical quality, mostly because it is not true.
If you want the formalist answer, I can give it to you--base ISO, 1/250s, f/11, on a 200lb tripod, in front of a high-contrast test target. Your images will always be the "best."
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I also ran across the MTF charts for some of the Mamiya RZ lenses some time ago and noticed something very strange for the 350 APO: its wide open measurements were even better than stopped down! How do the boffins explain that?
Speaking as a boffin (ahem...hate that word - thankfully it's rarely used in my country), the explanation is that in the absence of aberrations, every lens would perform at its best wide open, and become progressively less resolute as you stop down. So the 350 APO would appear to be a virtually unabberated lens at its wide open f5.6 setting.
One of the goals of lens design is to make the lens diffraction limited at the widest possible aperture. Hitting a diffraction limit is good, and the sooner you hit it the better - this tends to confuse some photographers, who have been often warned off stopping down too far "in case you hit diffraction", and for whom the word diffraction has only negative connotations.
I say "a diffraction limit" because there is no single diffraction limit for a lens with an iris. Every time you change the f-stop, there is a new diffraction limit; hopefully the lens performs to this limit at this f-stop.
Ray
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Hello ScubaZ,
Hasselblad provides an excellent resource on our website (hasselbladusa.com > downloads > datasheets) HC Lens book. It offers an informative and easy to understand guide on how to read and interpret an MTF (Modulation Transfer Function) chart. Traditionally HC/HCD lenses are tested at maximum aperture and two stops down. The information provided in the MTF will show the resolution in LP/mm from the center of the image area to the image edges and corners. You can see where or at what point the resolution start to decline as it nears the edge of the image, most noticeable with a wide angle optic.
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Spurred by this discussion, and for my own curiosity, I did a very un-scientific test of my three lenses (35, 50 mk.i and 80) with and without HTS. I shot my bookcase at a distance of about 5 feet and simply looked at the results at 100% on the screen in the center and corners at the plane of sharp focus (as well as I can focus the camera and align it with the shelf, assuming the shelf is straight, etc). I've posted the spreadsheet with my observations, again very un-scientific. They are more or less in line with what's been observed in this thread: best results from 8-16.
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Spurred by this discussion, and for my own curiosity, I did a very un-scientific test of my three lenses (35, 50 mk.i and 80) with and without HTS. I shot my bookcase at a distance of about 5 feet and simply looked at the results at 100% on the screen in the center and corners at the plane of sharp focus (as well as I can focus the camera and align it with the shelf, assuming the shelf is straight, etc). I've posted the spreadsheet with my observations, again very un-scientific. They are more or less in line with what's been observed in this thread: best results from 8-16.
Very good Jonathan - that's the way to do it.
Question though - on the 80mm with the HTS, at f/16 and f/22 you describe the center as "Good" and the edges as "Excellent". By this did you find the edges sharper than the center? Or was this meant as relative to expected performance for the edge, and the performance was better than your expectation?
Thanks,
Steve Hendrix
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Steve -
I'm traveling now and don't have access to the image. The impressions were absolute, not relative. That is to say excellent meant that the image was very sharp, good meant sharp, and so on.
However, it is entirely possible that my method of comparison may have colored the results. I looked at each section of the image (center, corners) and compared the sharpness at various apertures. I can't recall if I made a careful comparison between the corners and center of the 80.
I was quite impressed by the 80. I found it to be extremely sharp in comparison to the others.
Having said that, I've blown up images from the 50mm and HTS at f/22 to 44x60 inches and found them to be excellent from corner to corner.
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The modern H lenses are designed with more specfic reasons and are all quite good, of course, some better than the other.
The sharpness is not achieved just by f setting but also the focusing distance. I am very happy with most of the H lenses so it did not bother me to try to find the sharpest apeture, but I would assume except for wide angles H (28/35/50) and the 35-90 zoom the best sharpness will be at more dustant focusing while lens ideal for portraits (100. 150, 210) will be best at common portrait focusing distance.
Pingang
Shanghai