Film Reciprocity Failure Calculator
Enter your metered exposure time and film stock to get the corrected long-exposure time that compensates for reciprocity failure.
Reciprocity Calculator
Time your light meter shows — before correction.
Quick Presets (metered seconds)
Select a film stock and enter your metered time to see the corrected exposure.
Film Stock
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Metered Time
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Extra Time Needed
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Corrected Exposure Time
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Set this time on your camera or cable release.
Exposure Breakdown
| Metered time | — |
| Reciprocity correction factor | — |
| Extra time to add | — |
| Corrected time | — |
Formula Used
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Summary
Enter your metered exposure time and film stock to get the corrected long-exposure time that compensates for reciprocity failure.
How it works
- Select your film stock from the dropdown.
- Enter the metered exposure time in seconds (the time your light meter recommends).
- The calculator applies the stock-specific reciprocity correction formula.
- Read the corrected exposure time and the extra time needed.
- Use the corrected time on your camera or cable release timer.
Use cases
- Night photography on film where exposures exceed a few seconds.
- Astrophotography with film — star trails or landscape under the Milky Way.
- Architectural interiors photographed with slow film at small apertures.
- Waterfall long exposures on slide film such as Fuji Velvia.
- Pinhole photography where exposures routinely exceed 30 seconds.
- Any film exposure beyond 1 second where the metered time will underexpose.
Frequently Asked Questions
Last updated: 2026-06-11 ·
Reviewed by Nham Vu