Hi Rainer:
Thanks for that information! Someone ought to lend you an early 55mm
f/1.2 for analysis, also.
My reshoot of the radioactive vs. non-radioactive 50mm f/1.4 shows no
difference center or corner at f/1.4 - contrary to what the previous
shoot showed. The bottom line might actually be focusing accuracy. At
the risk of getting off subject for this thread, does best focus occur
when the image on a 2-4 screen shimmers (that is, seems to dissolve into
the grain of the focusing screen and twinkle when the eye is moved in
the slightest), or is it when the image (very small text) is most
legible just before or just after the shimmering? This side by side
comparison was made by focusing at the shimmer point, which logic would
suggest is the best point? But is it really? Obviously I need to shoot
the next so that I get the three focus points and then look at the
results to determine which is best.
Some might ask why I don't just stick to a biprism split image. I recall
an feature article once that claimed the biprism, which seeming to the
eye to be a precise way of focusing, wasn't necessary the most accurate.
Just look at a biprism from a slightly different position in the
viewfinder and the split image shifts some. Another article once said
that if we take too long to find best focus we've probably lost the best
point. The best point is found most often by focusing quick and
decisively. Well, that is hard to do with a lens that is a C or D SQF
grade wide open, no matter if its a fast lens or not and if you are
using a Varimagnifinder at 2.5x (like I am) or not.
I now have in hand a radioactive f/1.4 which doesn't have a frozen
diaphragm, so when my stock of film arrives I'll shoot it at all
apertures.
Gary Reese
Las Vegas, NV
P.S.
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