Definition of reciprocity failure in English:

reciprocity failure

noun

Photography
  • [mass noun] Deviation of an emulsion from the principle that the degree of darkening is constant for a given product of light intensity and exposure time, typically at very low or very high light intensities.

    • ‘Now if you have read about time exposures you will have come across the phrase ‘reciprocity failure’ with long time exposures.’
    • ‘The next fact is that you also do not need to know anything about shutter speeds, zoom lenses, reciprocity failure or the like.’
    • ‘There's something called reciprocity failure which basically means that for exposure times above 1 second, the film takes longer to do what it should be doing and as a result, interesting qualities of light and shade develop.’
    • ‘Those of you who have read books and magazines will have read about ‘reciprocity failure’ with long time exposures.’
    • ‘I've always thought this was a deliberate affectation, the result - in the case of photography - of six years of art school spent learning about reciprocity failure, platinum printing and other arcane chemistries.’