How much ND do you need?
Type how bright the scene is and how your camera is set. You get the ND to put on, rounded to the whole stop, and what is left over.
Put on the lens
ND 1.8
Rounded to the whole stop and named as a standard filter from ND 0.3 to 2.1, as the app does. Past 2.1 you need a stack.
How it works
Your ISO, stop and shutter add up to an exposure value. The light in front of you has one too. The difference is how many stops of ND you need: every 0.3 of density is one stop, so ND 0.9 is three stops, also sold as ND8. The tool rounds to the whole stop and names the standard filter, from ND 0.3 to ND 2.1, then shows what is left over.
Lux and foot-candles are turned into EV the way Cutvey Meter does it, as a reflected reading off an 18% gray surface (lux is about 2.18 × 2 to the power of EV100). The flicker line uses the app's own rule: a light on the mains pulses at twice the mains frequency, and a shutter is safe when it takes in a whole number of pulses. The flicker-free shutter calculator lists every safe shutter for your frame rate.
This is the app's own exposure solver (ExposureSolver and NDMath), with the same frame rates, angles, ISOs and stops it offers.
Typical daylight, at 24 fps, 180°, ISO 800, f/2.8
| Scene | EV100 | Lux, about | Stops to lose | ND |
|---|---|---|---|---|
| Full sun on sand or snow | 16 | 142,977 | 10.4 | Stack, 3.0 in all |
| Full sun | 15 | 71,489 | 9.4 | Stack, 2.7 in all |
| Hazy sun, soft shadows | 14 | 35,744 | 8.4 | Stack, 2.4 in all |
| Bright overcast | 13 | 17,872 | 7.4 | ND 2.1 |
| Open shade | 12 | 8,936 | 6.4 | ND 1.8 |
| Heavy overcast | 11 | 4,468 | 5.4 | ND 1.5 |
Typical published exposure values for daylight scenes; your light will differ, which is why you read it. Lux is the app's reflected conversion, so treat it as a guide.
ND by the numbers
| Density | Stops | Factor | Light let through |
|---|---|---|---|
| ND 0.3 | 1 | ND2 | 50% |
| ND 0.6 | 2 | ND4 | 25% |
| ND 0.9 | 3 | ND8 | 12.5% |
| ND 1.2 | 4 | ND16 | 6.25% |
| ND 1.5 | 5 | ND32 | 3.1% |
| ND 1.8 | 6 | ND64 | 1.6% |
| ND 2.1 | 7 | ND128 | 0.8% |
In the app
Your ND, live, while you point at the scene.
Set your rig once and Meter keeps the ND on screen as the light changes, or solves for the ISO, the stop or the shutter. The watch shows it on your wrist.
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