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How to read the Characteristics curve properly ?


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#1 Dominik Muench

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Posted 22 May 2005 - 08:19 PM

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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 ?
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#2 Dominic Case

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Posted 23 May 2005 - 08:49 AM

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.
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#3 Dominik Muench

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Posted 23 May 2005 - 05:14 PM

thanks dominic, so how do i have to convert those LogE into f stops ?
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#4 David Mullen ASC

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Posted 23 May 2005 - 06:28 PM

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

<{POST_SNAPBACK}>


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

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Posted 24 May 2005 - 09:48 AM

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.

<{POST_SNAPBACK}>


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
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#6 Dominik Muench

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Posted 24 May 2005 - 07:17 PM

hui confusing but i think i got it :) 5-6 stops latitude sounds great.
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#7 John Pytlak RIP

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Posted 24 May 2005 - 08:25 PM

The Kodak website has a tutorial about basic sensitometry and tone reproduction:

http://www.kodak.com...structure.shtml
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