How the calculation works
Keeping aperture and ISO unchanged, each stop doubles the exposure time.
filtered time = baseline time × 2^stops
Assumes constant light and exact stop density. Filter tolerance, colour cast, camera limits, light leaks, and film reciprocity are not modeled.
Field workflow
- Compose and focus before fitting a strong filter.
- Make and record an unfiltered baseline exposure.
- Fit and seal the filter; calculate the nominal duration.
- Use a timer or remote, then inspect sharp anchors, motion, clipping, colour, and edges.
Sources and methodology
This recipe draws on the sources below. You can check the original guidance from photography organizations and manufacturers:
- Nikon: Long-exposure workflow with moving water
- LEE Filters: Big Stopper exposure guide
- Nikon P7000 manual: stop-equivalence reference
