Nikon

They require no compensation or adjustment to exposure and many people leave them in place on the front of the lens permanently to act as protection for the much-more-expensive lens behind it.

The L1BC (Skylight) filter differs from the standard L37C (Ultraviolet) in that it adds a slight warmth to the scene and is particularly effective at giving a natural color when shooting in open shade where the light has a tendency to appear "cool.