ND filter

Definition

A neutral-density (ND) filter cuts light without intending to shift colour. Optical density 0.3 is one stop; ND8 / 0.9 is three stops; ND1000 / 3.0 is ten. New time = base time × 2^stops. Long-exposure water and bright-sun video at 180° shutter both live here. Cheap filters leak colour and sharpness; stack polarisers only if you accept the extra stops and the risk of cross-polarisation. Confirm on a test frame — meters behind heavy ND lie.

Calculators that use this

• Exposure & light

  ND Filter Exposure Calculator

  Multiply a base shutter speed by 2 to the power of ND stops to get the long-exposure time in seconds, minutes and hours.

• Exposure & light

  Exposure Value Calculator

  Convert aperture, shutter speed and ISO into EV at ISO 100 and EV at your working ISO. Use it to match meter readings or compare two camera settings.