A stop is a doubling or halving of light. This converter turns any number of stops — including thirds and halves — into the light factor, the percentage of light that gets through, the equivalent ND filter number and optical density.
Useful when comparing filters, flash power settings, bracketing steps or sensor dynamic range.
How to use the Exposure Stops Converter
- Enter stops (positive = less light, e.g. a filter).
How it works
Factor = 2^stops; transmission = 100 ÷ factor %; optical density = log₁₀(factor) ≈ 0.301 × stops.
FAQ
Why are ND filters labelled ND8, ND64, ND1000?
The number is the light factor: ND8 = 3 stops, ND64 = 6 stops, ND1000 ≈ 10 stops.
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