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05-16-2011, 09:31 PM   #16
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"So you meter an out of focus, evenly light white board to place that value 4 stop below middle gray at box speed, shoot, adjust subsequent exposures 1/2 (or 1/3 stops if you have lenses capable of that) above and below the initial metering. Measure the density of each frame and the closest one to 0.1 above fb+f will be your film speed which you determine by the number of stops or fractions thereof from the metered shot."

I will run a roll as you suggested starting at 4 stops below. So that I have it perfectly clear: simply shoot an evenly lit unpatterned whiteboard. Can the lab measure the density of each frame of the film base and fog ("fb+f")? I should choose the frame (and corresponding underexposure factor) which is .01 above the fb+f. Do I have it right?
Presently I am guessing the correction i.e. shooting ISO 50 Velvia at ISO 32.

Thanks for the help.

05-16-2011, 10:16 PM   #17
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QuoteOriginally posted by rmarkus Quote
"So you meter an out of focus, evenly light white board to place that value 4 stop below middle gray at box speed, shoot, adjust subsequent exposures 1/2 (or 1/3 stops if you have lenses capable of that) above and below the initial metering. Measure the density of each frame and the closest one to 0.1 above fb+f will be your film speed which you determine by the number of stops or fractions thereof from the metered shot."

I will run a roll as you suggested starting at 4 stops below. So that I have it perfectly clear: simply shoot an evenly lit unpatterned whiteboard. Can the lab measure the density of each frame of the film base and fog ("fb+f")? I should choose the frame (and corresponding underexposure factor) which is .01 above the fb+f. Do I have it right?
Presently I am guessing the correction i.e. shooting ISO 50 Velvia at ISO 32.

Thanks for the help.
My instructions were course and off memory I used for BW film. I'd read a procedure that you should be able to find on the web. The matt board should be more middle gray for slower films. It may need to be darker for faster films to give you a better range of apertures. I used a one-degree spot meter which I meter with normally. You can also use and change ISO settings if you're using your camera's meter instead of the aperture. You should get finer control that way.
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