Cokin
[Image:cokin.svg|200px|thumb|logo of cokin|right]
Cokin is a French manufacturer of optical filters for photography. The system allows filters such as rectangular graduated neutral density filters which are versatile in use.
History
[Image:Cokin-Filtersystem 01 08.jpg|left|thumb|Cokin Creative Suite]Cokin are particularly noted for their "Creative Filter System". It was invented by photographer Jean Coquin and introduced in 1978. Based primarily around square filters, these require a holder which is attached to the lens via a simple adapter ring of the appropriate size. Unlike screw-thread circular filters, which are each tied to lenses of a specific diameter, those in the system can be used with any lens, provided they are large enough to cover it sufficiently..
Production
The system includes a wide range of filters including color correction, plain and coloured graduated filters, diffraction, diffusion and polarizers. The material is a polymer, CR-39 sometimes advertised as "organic glass".Cokin produce various differently-sized versions of the Creative Filter System. The smallest is "A". The larger "P" system covers cases where "A" filters are too small to cover the lens. The still-larger "X-Pro" filters are 130mm wide. The "A" and "P" sizes in particular are de facto standards, with many other manufacturers producing compatible filters and holders. Cokin also produce a system for 100mm-wide filters which they refer to as "Z-Pro". "X-Pro" and "Z-Pro" are designed for larger cameras.