Ultraviolet filters are mainly used to protect the lens from dust, scratches, and damage due to accidental falls. They filter out ultraviolet light that can cause blue haze in photographs. They are useful when taking pictures in environments with a lot of ultraviolet light, such as mountains or the sea. They will filter out the blue haze that blurs the background of your photo. They are also helpful when taking photos in the snow, as snow effectively reflects ultraviolet radiation.