Reciprocity

Based on the film that you are using and the metered exposure time, calculate the exposure time to use to correct for the reciprocity correction and optionally the filter factors of the filters and the correction for the bellows extension that you might be using. Supports now also shutter speeds from 1/1000 seconds.

All information is contained in the App so no data connection is needed when you’re on a photo shoot abroad, on top of a mountain or in the deep countryside without any connectivity.

Normally there is a reciprocal relationship between light intensity and exposure time, but typically when exposure times get up to about 1 second or longer, this relationship breaks down. This is the so called Schwarzschild Effect and longer exposures are required to compensate for this or you'll risk underexposing your negative. Each film has different characteristics and this tool will calculate the exposure time to use based on the film and the metered exposure time.
The formulas used in this tool are taken from the film manufacturers' supplied data sheets and from the excellent Black-and-White Reciprocity Departure Revisited article by Howard Bond in the Photo Techniques magazine.


Currently, reciprocity failure information about the following films is included:
Bergger BRF 200
Foma Fomapan 100 Classic,
Foma Fomapan 200 Creative,
Foma Fomapan 400 Action,
Freestyle Arista EDU Ultra 100,
Freestyle Arista EDU Ultra 200,
Freestyle Arista EDU Ultra 400,
Fuji Neopan 100 Acros,
Fuji Provia 100F,
Ilford Delta 100,
Ilford FP4 Plus,
Ilford HP5 Plus,
Ilford PAN-F Plus,
Ilford SFX 200,
Ilford XP2,
Kodak Plus-X,
Kodak PROFESSIONAL T400 CN,
Kodak T­-MAX 100,
Kodak T­-MAX 400,
Kodak T­-MAX 3200,
Kodak Technical Pan,
Kodak TRI­-X 320,
Kodak TRI­-X 400