The Hitech 4 x 4" CC40R Red Filter is a color compensating (or color correction) filter for use when making color balance adjustments. They can be used to alter the color balance by placing in front of a light source, such as an enlarger, or can be used to help pre-visualize color adjustments when viewing prints.
The red filter is one of the three components to the additive color model, and when paired with blue and green, a full range of colors can be achieved. Red is opposite of cyan and is added to reduce cyan tones within a scene or print. This filter is CC40, with 025 being the least dense and 50 being the densest of the color compensating filters. A 0.6 stop increase in exposure is required for normal results.
This filter measures 4 x 4" / 101.6 x 101.6mm and is constructed from CR-39 dyed resin.