Sharpest aperture for Hasselblad HC Lenses

[ScubaZ]

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.

[ErikKaffehr]

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.

[BernardLanguillier]

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

[henrikfoto]

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

[John R Smith]

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

[BernardLanguillier]

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

[Rob C]

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

[henrikfoto]

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.

[henrikfoto]

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

[BernardLanguillier]

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

[ondebanks]

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 

Ray

[Michael H. Cothran]

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.

[Martin Wouterlood]

"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?

[Michael H. Cothran]

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".

[ErikKaffehr]

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".

[theguywitha645d]

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.

[jeremypayne]

I also believe using lenses for most things on Earth at something other than infinity. Crazy idea, I know ...

So true.

[ErikKaffehr]

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.

[theguywitha645d]

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.

[Steve Hendrix]

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