ND-filter exposure
Convert filter stops or optical density into an exposure time, including two stacked filters. Drag the graph handles to change inputs and explore the result.
Your inputs
Values shown are editable examples; verify your own measurements and product specifications. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- Filtered exposure = × 2^; = × log₂(10); Light transmission = 100 / 2^
- Worked example: 0.008 s × 2^6 = 0.512 s; D = 1.8 ⇒ 10^1.8 ≈ 63.09573445
Input and formula key
Your result
Complete the inputs to see your result.
Assumptions and limitations
Enter base exposure as decimal seconds: 1/125 s is 0.008. Both strengths use the selected notation; zero means no second filter. Each strength is limited to 0–12. Optical density D means transmission 10^−D; it is not an ND filter-factor label such as ND64. Stacked strengths add ideally. Assumes fixed aperture and ISO; ignores reciprocity failure, color shifts, vignetting and variable-filter artifacts.
Sources
- Nikon — neutral density filters and exposure Sources reviewed: 2026-10-09
- Edmund Optics — neutral density and optical density Sources reviewed: 2026-10-09
