NEUTRAL-DENSITY EXPOSURE ARITHMETIC
Less light.
More time.
Start with an unfiltered shutter duration you already know. Enter each filter’s strength, stack the losses, and see the ideal filtered exposure.
Aperture and ISO stay unchanged. No image upload, account or timer.
01 / INPUTS
Build your filter stack.
02 / IDEAL RESULT
The time multiplier.
- Total light loss
- stops
- Combined time factor
- Combined optical density
- Computed transmission
How the stack adds up
| Original entered basis | Stops | OD | Factor |
|---|
Conversions are calculated and displayed with rounding. The table keeps the original entered basis through notation changes.
No film reciprocity correction, manufacturer calibration, changing-light model or camera noise-processing delay is included. The result is a starting calculation, not a guarantee of exposure.
READ THE LABEL BEFORE THE NUMBER
10 stops.
OD 3.0.
Factor 1000.
They can appear together on filter packaging, but their literal mathematical values are not identical. Exactly 10 stops gives a time factor of 1024. Optical density 3.0 and literal factor 1000 each give a factor of 1000.
This calculator uses the notation you choose. It does not silently replace a factor with a nearby whole-stop value or infer a manufacturer’s convention from “ND” alone.
See the notation guide and worked examples →