Cokin Z-PRO 703 Color Compensating CC20C (Cyan) Resin Filter - Some photographic situations require specific color corrections. For example, when shooting daylight film under fluorescent lighting, some magenta correction is needed in order to remove the greenish tint that would otherwise appear.
The amount of color correction required is most accurately measured via a color temperature meter. Cokin Color Compensating filters are made of plastic and are available in three secondary colors: Cyan, Magenta, and Yellow. A typical designation for one of these filters is CC30M. The "CC" stands for Color Compensating. The "30" stands for a density of 0.30 and the "M" is for magenta.
The Z-PRO Series is recommended for focal lengths of 20mm onwards (in the 35mm format). This filter is made of CR39 Resin which is a reputable lightweight and shock-resistant optical material also used for ophthalmic glasses.