Film is sensitive to the ultraviolet rays in daylight that are invisible to our eyes. UV filters are used to absorb these ultraviolet rays which can cause outdoor photographs to have a blue color cast and a low-contrast haze that diminishes detail.

UV filters absorb the UV part of the spectrum without affecting exposure or the light in the region visible to us, so there should be little to no change in color balance. This is a useful filter to have for older cameras with lenses that weren’t multi-coated.