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- Development calculator
Tools
Development calculator
Choose a film and a developer, then the dilution, speed and temperature the time was published for. You get the maker’s time with the datasheet it came from — and, if you need them, NegaKit’s corrections for a warmer bath or a reused developer.
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Film
Lomography Lady Grey 400 · ISO 400 · B&W
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Developer
Only developers with published times for this film.
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Dilution
The only one published for this choice.
Dilution B (1+31) -
Speed
The only one published for this choice.
EI 400 box speed -
Temperature
The only one published for this choice.
20 °C
How the numbers are worked out
Only what is published
Every time is a maker’s or a source’s own, read off the datasheet linked beside it. Speeds, dilutions and temperatures are the ones published: nothing is extrapolated, so a push nobody published is simply not on the list.
A warmer or cooler bath
For black-and-white film only, and only between 18 and 26 °C: about 9 % shorter for each degree warmer, rounded to 5 seconds. It is the rule NegaKit’s developing timer uses, which follows Ilford’s and Kodak’s temperature charts closely in that range. Colour processes and monobaths are not corrected.
A reused developer
NegaKit’s chemistry rule: a reusable black-and-white developer at stock strength +10 % for each roll already through it, a colour kit +2 %. One-shot developers and working dilutions are used once, so they get no correction; nor does a monobath, which NegaKit has no rule for.