Cokin A Series Filters

Recommended for lenses between 36 and 62mm in diameter with a focal length over 35mm. Cokin square filters fit into a holder and are attached to a lens via an adapter ring, the photographer has a number of immediate advantages:

a) there is no need to duplicate filters to fit different size lenses,
b) up to three filters can be used at once to create unique effects,
c) the photographer has control over the positioning of the effect on the photograph.

How the Cokin System works

Screw the adapter ring onto your lens. System "A" rings come in the following diameters; 36/37/39/40.5/41/42/43/43.5/44/46/48/49/52/54/55/58/62mm and Hasselblad special rings.
Slide the filter holder on the adapter ring until it snaps in place. The filter holder is now solidly attached to the lens, yet it can rotate both left and right.
Slide the filter into one of the filter holder slots. The one closest to the filter holder housing is the narrowest; it allows the use of round filters with notched edges (polarizer, star filters..). The two central slots are intended for square filters. The outer slot can be used either for an additional filter or for a coupling ring.
Most popular filters - There are over 140 filters to choose from in the range. The most popular are:

Polarizers
Designed to eliminate unwanted reflections and darken skies.
Graduated
Add color to a scene by using a Cokin graduated filter to enhance a dull sky, or use a Sunset filter to add warmth.
Pastels and Diffusers
Ideal for portraits, still life and landscapes, to create a moody atmosphere and a softer effect.
Warm-up Filters
Add warmth to a portrait shot, giving improved skin tones.
Colour Filters
Colour correction filters are available, as are Neutral Density filters and filters specifically designed for use with black and white film.
Optical effects
There is a wide range of filters available to add special effects to photographs, such as Starbursts, Multi-image, close-up, Rainbow, Double exposure etc.