Camera
ND Filter Calculator
Find the ND strength to hold your aperture and shutter in bright light.
Runs entirely in your browser. Nothing is uploaded.
How to use
- Pick the scene brightness that matches your conditions, from open sun to shade.
- Choose the cinematic shutter you want to hold, usually near double your frame rate.
- Set the aperture and ISO that give the look you want.
- Read how many stops of neutral density you need and the nearest real filter to fit.
Examples
- Shooting 1/50 at f/2.8 and ISO 100 in open sun needs roughly five to six stops of ND, so an ND32 to ND64 holds the shallow look without overexposing.
- In overcast light the same settings may need only two or three stops, an ND4 to ND8, because there is far less light to cut.
- Stopping down to f/8 instead of fitting an ND reduces the ND needed by several stops, a quick trade when you do not have the right filter on hand.
Frequently asked questions
Why use an ND filter at all?
On video you usually want a shutter near double your frame rate for natural motion blur. In bright light that shutter overexposes at a wide aperture, so a neutral density filter cuts the light evenly and lets you keep both the shutter and the shallow depth of field.
What do ND numbers mean?
The factor, like ND8, is how many times the light is reduced. ND8 cuts to one eighth, which is three stops. Optical density, like 0.9, is the same thing on a log scale where every 0.3 is one stop.
What is a variable ND?
A variable ND rotates to cover a range of strengths in one filter, convenient for changing light. The trade is possible colour cast and cross patterns at the extremes, so many shooters prefer fixed filters for critical work.
