How to read the Characteristics curve properly ?

Dominik Muench · May 23, 2005

this is the characteristics curve of the black and white reversal trix from kodak.

do i interpret that curve right that this stock has a latitude of around 2 1/2 F stops ?

Dominic Case · May 23, 2005

It's hard to read this curve accurately (thanks, Mr Kodak:-( ), but the curve reaches from about -0.5 to -2.2 on the logE exposure scale. (That's not all straight line, it includes toe and shoulder gradations.

What that means is that the film has a useful exposure range of about 1.7 logE, which is just under 6 stops. I don't like to use the term latitude for this: latitude is really how much you can vary your overall exposure for a certain set-up, and get away with it. In a 6-stop (64:1) ratio scene, you have zero latitude with this stock. Anything with a greater range, will be crushed or burnt out.

I don't have much (any) experience with the new Kodak b/w reversal stocks, but the curves published on the Kodak website are so dramatically different from the older stocks that I hesitate to draw any conclusions. Perhaps John could elaborate a little more.

Dominik Muench · May 23, 2005

thanks dominic, so how do i have to convert those LogE into f stops ?

David Mullen ASC · May 23, 2005

thanks dominic, so how do i have to convert those LogE into f stops ?

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Just like the ND filter series, every .30 logE = one stop of density, right Dominic?

Sam Wells · May 24, 2005

What that means is that the film has a useful exposure range of about 1.7 logE, which is just under 6 stops.

I don't have much (any) experience with the new Kodak b/w reversal stocks, but the curves published on the Kodak website are so dramatically different from the older stocks that I hesitate to draw any conclusions. Perhaps John could elaborate a little more.

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I haven't shot this one either but lots of the previous Tri-X and I'd say 5 stops (maybe a touch more) was the useful working range.....

-Sam