The Tiffen #4 Viewing filter is for process photography. Balancing lighting by eye is a matter of experience. Decisions can be aided through the use of contrast viewing filters. These are designed to handicap the eye, with its much greater range of apparent densities, to resemble the range of the various types of film.

Use contrast viewers to judge relative highlight and shadow densities

There are viewers for black-and-white film, as well as various viewer densities for color film

A darker viewer is used for slower film speeds, where you would tend to use brighter lighting; Faster film, which can be used in dimmer settings would require a lighter viewer

Tiffen Viewing Filters

The #1 is for black-and-white imaging

The #2 viewer is for film speeds to 100

#3 is for faster film; They can be used for video, as well, with the #3 being better suited for lower light levels

The green #4 viewer is for process photography

The blue #5 is for blue screen work, as well as for setting up color video monitors

Black and White Camera Filters

Tiffen #4 PROCESS VIEWING FILTER