Used with black and white film to improve subject contrast. A colour filter has the effect of lightening its own colour and darkening opposite colours. When used with colour film, the result takes on the colour of the filter.
RED Absorbs 3 stops. Turns blue skies black, and exaggerates cloud effect. Simulates night effect by under exposure. Cuts through haze. Gives stark contrast to light colour buildings against a deep sky. Darkens greens, lightens reds and yellows. Used with colour film to give exaggerated sunsets. Also commonly used in infra red photography.
ORANGE Absorbs 2 stops. Similar to red, but not as extreme. Increases outdoor contrast. Good for distant landscapes and enhancing textures of brickwork or stone. Darkens blues and greens.Enhances a sunset when used with colour.
YELLOW Absorbs 1 stop. Enhances cloud effect by slightly darkening blue sky. Improves buildings against the sky. Lightens yellows, darkens blues.
GREEN Absorbs 1.5 stops Improves contrast for fields, trees, flowers etc., by lightening foliage. Useful for landscapes. Lightens greens, darkens oranges and reds. Also used for indoor portraits under tungsten light, but will exaggerate red skin blemishes.
YELLOW/GREEN. Absorbs 1.5 stops. Similar to GREEN, but good for outdoor portraits. Improves skin tones, but may exaggerate freckles.
