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Old 25th July 2020, 11:38 PM
maxwellmakosk maxwellmakosk is offline
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Location: Hackney, London
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Default What is CL? / Creating XTOL Temp Converter

I am in the process of writing a program to reliably convert XTOL times/dilutions/speeds to different temperatures. I have no clue what to expect so to start I am just assembling all the data available to me and generating exponential functions for each time/dilution/speed set I can find. When Going over Kodak J-109 I noticed to the right of the speed column there is one labelled "CL" with values ranging from roughly 0.5-0.9. What in the world is this? Never come across it before then again Ive never looked this closely at any Kodak documentation.

In addition would any experts have any suggestions on what to expect from this endeavour in terms of temp conversion in general? I've made a program for HC110 before which used an arbitrary formula and just converted values you threw at it but for this XTOL program I want to be more precise. I am aware that its bad practice to use any "universal temp conversion" charts such as the infamous one from ilford but how nuanced is it really? I remember reading a discussion with PE from photo trio on the subject a while ago (which I cannot find anymore) and the general consensus there was that conversion rates differ per film AND per developer, so I may have a ton of work ahead. I am curious how much these rates differ. In any case these are questions I hope to answer myself in due time but any input is much appreciated

Edit: Just realised it CI not CL whoops! Should have noticed with "Exposure Index" right next door but the I,L switch up will always confuse me.
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