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05-22-2016, 09:02 PM   #46
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QuoteOriginally posted by reh321 Quote
and we all know that extra glass in the path reduces sharpness.
Believe it or not, air does too, which is one of the reasons why drum scanners use a wet process for imaging. By decreasing refractive differences and diffraction/scattering due to surface imperfections between the medium/fluid/imager interface, it also allows for greater transmission of light, increasing dynamic range and allowing for clearer delineations between tones.

Similar principles are at work in oil immersion objectives for optical microscopes, which allow significantly higher magnifications than air gapped ones do.

05-22-2016, 09:20 PM   #47
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Ironically the GLASS in the path even if flat can matter and can IMPROVE resolution. The M43 speed boosters made by Metabones were shown in resolution tests to improve resolution. When tested by Lensrentals on their frankenmachine they couldn't duplicate it - it was worse then the designer had an ah ha moment and pointed out that the M43 sensor had a fairly thick bit of glass on the front that affected how the light reached the microlenses. They added a bit of plain optical glass of similar thickness to the stack and all of the sudden the dang thing worked!
05-23-2016, 12:01 AM - 1 Like   #48
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QuoteOriginally posted by stevebrot Quote
We both know that is unlikely to happen, not because it can't be done, but because it is not worth the effort. Back to the original question regarding legacy lens performance on film and presumably on digital, I can provide a fairly ancient (1978 from Modern Photography) article that details a test of a half-dozen lenses that made 100+ lp/mm against readily available films of the time. All were capable of coming within 0.5 lp/mm of or exceeding the pre-Bayer interpolation K-1 figure of 102.5 lp/mm. I would expect that those same lenses should be in the same range in 2016.

All sizes | How Sharp Can You Get? | Flickr - Photo Sharing!
All sizes | How Sharp Can You Get - continued | Flickr - Photo Sharing!

(Many thanks the @Nesster for his scans. Originally shared as part of a previous thread on resolution in 35mm film photography)


Steve

(...the Summicron 50/2, don't know which version, made 89 lp/mm with KII...)
It may not be worth it to you, but it certainly is worth while to me. If I am wrong I want to know it.

Here is the test that I will set up. I will load my MZS with Velvia 50 since that seems to be the highest resolution color film currently available. I will put my best lens which is an FA 50 f1.4 - use it at f5.6 and f6.3 with the camera mounted on a tripod to take the pictures. I will then put the lens on my K-1 and take the same picture from the same location.

Tell me where to send the film to get the best development job done on it.

Tell me where to send the best of the slides to get it drum scanned.

No sharpening applied to either the scan or the K-1 shot.

I will post the results which ever way they go.

Is this a fair test? Or do the rest of you have problems with it?

Last edited by HoustonBob; 05-23-2016 at 06:36 AM.
05-23-2016, 10:10 AM   #49
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QuoteOriginally posted by HoustonBob Quote
It may not be worth it to you, but it certainly is worth while to me. If I am wrong I want to know it.

Here is the test that I will set up. I will load my MZS with Velvia 50 since that seems to be the highest resolution color film currently available. I will put my best lens which is an FA 50 f1.4 - use it at f5.6 and f6.3 with the camera mounted on a tripod to take the pictures. I will then put the lens on my K-1 and take the same picture from the same location.

Tell me where to send the film to get the best development job done on it.

Tell me where to send the best of the slides to get it drum scanned.

No sharpening applied to either the scan or the K-1 shot.

I will post the results which ever way they go.

Is this a fair test? Or do the rest of you have problems with it?
Why limit yourself to color given the fact that you acknowledge that black and white has higher resolution? Given that black and white was used long before color I would expect that is the "worst case" design that the lenses were designed for.

Overall I think that you will fibd that these lenses far exceed the film limitations. I think many digital lenses will not be particularly better than the film lenses at least in the realm of primes. Zooms in the FA or F era that are at the high end also may have greater resolution than you seem to expect.

05-23-2016, 11:34 AM   #50
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QuoteOriginally posted by HoustonBob Quote
Is this a fair test? Or do the rest of you have problems with it?
Again, I don't see the rational of doing this. Did you click through on the links I provided? Did you read the second half where methods and results are discussed? The issue is not whether film can resolve, but whether the lens can resolve. The answer is yes. The lenses that made 100+ lp/mm on the test were all commonly sold as kit and are fairly representative of the better lenses of the time.

Since it is lenses you want to test, I suggest:

PDML Lens Testing Procedure

Edit: -- or --

http://bobatkins.com/photography/technical/lens_sharpness.html

...with these modifications:
  • I would strongly suggest other than color film. After all, I don't believe any manufacturer claims better that 50 lp/mm at 50% contrast for any color material. After all, we are testing lenses, not films. I suggest TMax 100 as representative of a modern emulsion. It is rated to ~130 lp/mm at 50% contrast by Kodak.
  • Best of ten focus attempts at each of your chosen apertures*
  • If possible, don't use the MZS. Use a camera with split image focus screen. If you don't have a body with that feature, limit your focus attempts on the K-1 to the optical viewfinder to level the playing field. The optical viewfinders on both cameras are equivalent in regards to focus sensitivity.
  • Don't use the focus confirm on either camera (PDAF on the MZS has focus sensitivity of about f/5.6 vs. f/2.8 on the K-1)
  • No pixel shift
  • Repeat the test using your best "modern made-for-digital" lens
Again, I don't see the rational. If you want to support your claim of inferior design for FA-series and older, it should be enough to test old against new on your K-1 using magnified live view. Whether film can capture same is irrelevant to your initial claims; unless, of course, you merely want to prove your critics on this thread wrong on a point-by-point basis. If so, I wish you the best of luck** and deep pockets. Drum scans at 8000 dpi are expensive (~$50 USD per frame).

Why I stated that doing a head-to-head test is "not worth the effort" may be summed up by the conclusions of the staff at Modern Photography in 1978 (see links in comment above):

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Steve

* The big challenge to doing resolution testing is attaining accurate focus. Depth of field is no help here. (Magnification defeats DOF.) That is why multiple focus attempts and/or focus bracketing are essential when doing lens tests.
** Folk on online forums can be amazingly tenacious. Strangely, they also lose interest quickly and drift away.

Last edited by stevebrot; 05-23-2016 at 12:09 PM.
05-23-2016, 12:14 PM   #51
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@HoustonBob FA50/1.4 is a good lens choice for your experiment given its known 97 lp/mm resolution on TMAX 100 in the center from f/5.6 - f/11. Of course, you would want to test several examples to control for sample variation, using standard resolution targets, under tightly-controlled studio lighting conditions. A lens bench would actually be better.

Though imperfect, here is a link to the methodology Yoshihiko Takinami used when testing the various lenses twenty or so years ago. It was a modification to the accepted PDML test procedure created by the best users and thinkers of the time in the Pentax global community.

Last edited by monochrome; 05-23-2016 at 12:20 PM.
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