ND filter
The ND filter table gives, for each neutral density (ND) filter, its light reduction and the shutter speed you get from your speed without filter. Open it from the side menu, in the tables section.
Reading the table
Section titled “Reading the table”Each row is a light reduction from 0 to 16 stops, in steps of a quarter, third, half, two thirds and three quarters of a stop. Whole-stop rows are highlighted.
| Column | Meaning |
|---|---|
| ND | the filter factor: ND2, ND4, ND8… ND1000. It divides the light by that number. |
| Optical density | the manufacturers’ notation: 0.3 per stop (ND 0.9 = 3 stops, ND 3.0 = 10 stops) |
| Light reduction (stops) | the number of stops taken away |
| Speeds | the speed you get with the filter, for two starting speeds you choose at the top of the columns |
Example: at 1/125 s without filter, an ND1000 (10 stops) gives an exposure of about 8 seconds.
How to use it
Section titled “How to use it”- Without the filter, meter the scene and note the shutter speed.
- Choose that speed at the top of one of the two columns: comparing two starting speeds helps when the light hesitates between two values.
- Find your filter’s row: it gives the new speed, with the same aperture and ISO.
- Screw on the filter, switch to manual mode (or Bulb beyond 30 s) and shoot.
- Frame and focus before screwing on the filter: with a strong ND, viewing and autofocus become impossible. Then switch to manual focus so it doesn’t change.
- Cover the viewfinder eyepiece during long exposures: stray light entering through the viewfinder can fog the image.
- Filters add up: an ND8 (3 stops) and an ND64 (6 stops) stacked take away 9 stops. Optical densities add up too.
- Colour cast: very dense filters can tint the image; a RAW file lets you correct the white balance.
- For long exposures, the Equivalent exposure tool helps find other combinations of settings, and the Countdown tool helps time the exposure.