Long Exposure Timer is created for long exposure photographers by a long exposure photographer. It has time increments based on 1/3 stop exposure adjustments, and allows you to add up to 20 stops for filters or other adjustments.

Meter the shot without your filter or with the ISO turned up, enter the time, and the number of stops to add for your filters or ISO/aperture adjustments, and the adjusted exposure will be calculated. If the adjusted exposure is over 3 seconds, you can use the timer for the exposure.