For Digital camera, or Film camera with B&W films. With a Digital camera, can be used in either color mode, or B&W mode. For Black& White mode, set the menu on “B&W” position & use it like a Film camera. Red filter must be used for extreme contrasts. By severely contrasting blue sky to almost black, it gives your pictures a dramatic character. By contrast, the clouds becomes more brilliant Recommended for lenses between 36 & 62mm in diameter with a focal length over 35mm. Cokin square filters fit into a holder & are attached to a lens via an adapter ring. There is no need to duplicate filters to fit different size lenses. Up to three filters can be used at once to create unique effects. The photographer has control over the positioning of the effect on the photograph.