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Film Test — Cape Perpetua, Oregon

April 6, 2011

April 2. Finally had a day that was periodically without rain! UV Index 2. I took the next run of 'TLF#2' out to test. This batch had one drop of Steigmann's gold sensitizer added at the start of the second ripening/digestion. There was no detectable increase in either speed or fog.

I shot this 120 roll with the Fuji 690III-90 mm, bracketing four exposures for two scenes — 1 sec at f/16, f/11, f/8, and f/5.6. The printed image shot out to sea was at f/8; the one upstream was f/11.

"Speed" is a most problematic concept with colorblind emulsions. They are only significantly sensitive to UV light and that changes throughout the year and with latitude, elevation, and weather conditions. The assignment of an ASA number is relative at best. When the emulsions were new and being figured out there were elaborate charts of speed conversion factors as related to latitude and time of year.

Today, in addition to those charts, we have the EPA UV Index. I'm going to try to develop speed guidelines to my favorite emulsions as I go along. I suspect it will take a full year of taking careful notes after I settle on final recipes. Until then, and probably afterward, there's always bracketing!

UV Index

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