The Cokin Warm (81A) Colour filter is for use with a film camera using daylight colour film or a digital camera in "automatic" mode. Colour correction filter which decreases the colour temperature from 3400ºK to 3200ºK (makes it more red) to reduce the blue cast & warm-up the tones. The Warm (81A) Colour filter is great for landscapes or portraits (to warm-up the skin). The 3 filters 81A / 81B / 81C can be combined with each other for maximum effect.