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:

ADOX CHS 25

ADOX CHS 100 II

ADOX CMS 20 II

ADOX PAN 25

ADOX Silvermax

ADOX SCALA 160

AGFAPAN APX 100

AGFAPAN APX 400

Bergger BRF 200

Bergger Pancro 400

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

Fujichrome Provia 100F

Fujichrome Sensia 100 [RA]

Fujichrome Sensia 200 [RM]

Fujichrome Sensia 400 [RH]

Fujichrome Velvia 50 [RVP50]

Fujichrome Velvia 100 [RVP100]

Fujichrome Velvia 100F [RVP100F]

Fujicolor PRO 400H

Fujicolor PRO 800Z

Fujicolor SUPERIA REALA

Fujicolor SUPERIA 100

Fujicolor SUPERIA 200

Fujicolor SUPERIA X-TRA 400

Fujicolor SUPERIA 1600

Fujicolor TRUE DEFINITION 400

Fujicolor SUPERIA X-TRA 800

Fujicolor PRESS 400

Fujicolor PRESS 800

Holga 400

Ilford Delta 100

Ilford Delta 400

Ilford Delta 3200

Ilford FP4 Plus

Ilford HP5 Plus

Ilford ORTHO Plus

Ilford PAN 100

Ilford PAN 400

Ilford PAN-F Plus

Ilford SFX 200

Ilford XP2

Kodak Ektar 100

Kodak Plus-X

Kodak Portra 160

Kodak Portra 400

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

Lomography Earl Grey

Lomography Lady Grey (past mid 2017)

SPUR DSX