ND Filter Calculator - Available on the Download Page

Expanded and updated:

This table works for all ND filters. ISO is not a factor.

Example 1

Set your preferred aperture and meter the scene. [f11]

Note the shutter speed required. [1/160th]

Read the Exposure Value [EV] for 1/160th at f11 [EV14.3].

Read up the f11 column

A 10 stop ND filter would be 14.3-10=EV4.3

Read across from 4.3 to get the shutter speed of 6 seconds

or

A 4 stop ND filter would be 14.3-4=EV10.3

Read across from 10.3 to get the shutter speed of 1/10 of a second

Switch to Manual mode on the camera and fit the ND filter

Shoot at the required settings


Example 2

Set your preferred aperture and meter the scene. [f4]

Note the shutter speed required. [1/6th]

Read the Exposure Value [EV] for 1/6th at f4 [EV6.7].

Read up the f4 column

A 10 stop ND filter would be 6.7-10=EV-3.3

Read across from -3.3 to get the shutter speed of 166 secs [2min 46sec]

or

A 4 stop ND filter would be 6.7-4=EV2.7

Read across from 2.7 to get the shutter speed of 2.5 seconds

Switch to Manual mode on the camera and fit the ND filter

Shoot at the required settings