The Tiffen 3 x 4" CC30R Red Filter is a color compensating (or color correction) filter for use when making color balance adjustments. It can be used to alter the color balance of a scene by placing in front of a light source or the lens of your camera. It can also be used to apply color corrections when used in the darkroom with an enlarger or to help pre-visualize color adjustments when viewing prints.
Red is the opposite of cyan and can be used to reduce cyan tones or casts within a scene or print. This red CC30 is more dense than a CC20 filter and less dense than a CC40 filter, and requires a 0.6 stop compensation for normal exposure results.
Tiffen filters are made using ColorCore technology; a process that involves laminating the filter substrate between 2 pieces of optical glass and grinding flat to a tolerance of 1/10,000th of an inch. This filter measures 3 x 4" / 76.2 x 101.6mm.