Arent most good films around the 60 lp/mm at 1.6:1 contrast ratio? That is what I call useful resolution, ie: across the texture of an object, the 1000:1 figure is for shooting sharp-edged silhouette backlit tree branches against a white sky...
160:1 contrast resolution would be how sharp one edge is next to edge that is 7 and 1/3 stops difference, not the resolution of a scene that is 7 and 1/3 stops wide. You're extremely unlikely to find any 7 and 1/3 stop edges in any kind of normal exterior scene, the transitions are much lower than that, and most transitions are not hard-edged, you wont get that on the hard edge between direct sun and shadow either, you'd have to set up a controlled situation where there is no ambient bounce back into the shadows.
The texture of bark or someone's skin etc, is not going to be 7 and 1/3 stops of variance over those surfaces as a whole, let along as the texture/transition from each "line" of the surface, surface detail is going to be in the 1.6:1 vicinity.
Good point. I have some RIT resolution targets with varying contrast (three different setting, I believe). They clearly show the influence of subject contrast on resolution measurements. I also measured my USAF 1951 targets, which I bought from Edmund's Scientific. They have a density range (black printing vs white paper) of over 100:1.
Here are two examples. An Olympus 50mm 1.4 SLR lens vs a Leica 50mm 1.4 rangefinder lens.
I checked my files. The RIT targets come in three different contrasts:
32:1, 6.3:1, and 1.6:1
Those seem to be especially thorough and well-done tests.
I don't have either lens, but the results could seem to fit their reputations (Olympus over-corrected for outer edge?)
Where can I find more?
Best regards
Too bad they did not test the f1.4 Planar 50mm at that time. Later they tested a Contax and ran that cameras Planar 1.4 50mm individually. I can't find that one currently, but as I recall it was between the Zuiko and the Leica Rangefinder lens. I believe the Planar was very similar to the Leica SLR lens. I need to do some more digging.
Lots of good points here. Need to be careful of terminology though. Any lens is always diffraction limited at its maximum aperture, since the Airy disk size is only a function of the aperture diameter. The best performance may be found at smaller than maximum apertures due to better optical correction by stopping down.
Thank you, that was well stated. The last paragraph hit home because I keep thinking about going into LF.
Steve
Don't forget about the increased ability to crop and get a better composition with LF which often results in better pictures. It's not all about lp/mm.
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