Reciprocity Calculator #

Description #

Reciprocity Failure Calculator and Timer needed for long exposures.

Most colour negative and black and white films demonstrate reciprocity failure for exposures longer than one second. The longer film is exposed to light, the less sensitive it becomes, so longer it needs to be exposed.
Meter a scene as normal. Enter the metered value into the Metered Exposure (seconds) form field and expose the frame for the Calculated Exposure (seconds).
If your film brand is not listed, use Generic colour-negative or Generic black and white for your shot.