Hi all:
Based on testing I did at about 1:9 magnification ratio, the 50 mm f/3.5 Macro
Zuiko had a noticable loss of resolution and contrast at f/22, as well as
f/3.5~4 I used to "microfilm" 9" x 9" aerial photo contact prints onto
Kodak's Direct Positive Film (with an E.I. of only 8 of something). It took
f/5.6 to get a big jump in performance, but the exposure time under cross
polorized photofloods was too long. So I got the 50 mm f/2.0 and the ability
to shoot at f/4.0 with great results. I don't recall that I got any better
definition with the f/2.0 at f/4.0 versus the f/3.5 at f/5.6, but it was a
case of getting the right tool for the job.
Sometimes these diffraction degradations (and large aperture limitations) take
comparison tests to detect! I sold the f/3.5, but there sure are times I
could live with and want the f/22 setting. I see that the 50 mm f/3.5 Canon
FD I picked up for $27.50 (with FD 25 mm tube) goes to f/32. Yikes, I bet
that isn't too sharp a setting.
Gary Reese
Las Vegas, NV
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