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Hello! I’ve been using written gelatin filters -
#8 yellow, #25 red, #47 blue, and #59 green. The focusing seems
repeatable for each filter. I’ll try stopping the lens down to
f4 and f5.6 and see how the coma does. Hopefully, f4 will do it.
F5.6 would seem to be too slow to be worth the effort. If the unfiltered light reciprocity test
seems reasonable/repeatable with the 5000K fluorescent bulb, then I can try the
test with each filter color to get some data for light at different wavelengths
to take into account the differences in the reciprocity characteristics of film
at different wavelengths wavelength. What I’d like to get from these
initial tests with TMax is whether pre-flash and/or hydrogen peroxide
hypersensitization can yield a reasonable increase in speed over a twenty
minute exposure. If so, then I’d like to try Tech Pan. If
Tech Pan also has a reasonable increase in speed over a 20 minute exposure then
I can use preflash or hydrogen peroxide hypersensitization so that I can use
Tech Pan for hydrogen alpha exposure (maybe luminance as well, though I doubt
that would be needed with 4x5), rather than gas hypersensitization, which I
cannot use at present. Thank you for the input. Best
regards. Mike --- |
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