Film Reciprocity Calculator
Here is our calculator for working out the adjustment needed for long exposures. As film is exposed its sensitivity changes, and more light than metered is required. This calculator will work out the actual time needed depending on your film.
Reciprocity calculator
Film loses sensitivity on long exposures. Pick your stock, enter your meter reading, and get the corrected time.
Type seconds (30), a fraction (1/4), or minutes and seconds (2:30). Meter without the ND filter.
Corrected exposure
–
0:00
A tone plays when the exposure ends. Keep this page open during the exposure.