Cinematography demands a great deal of cameras and lenses. It therefore makes sense to protect sensitive front element of the lens against rough conditions.
Clear filters fulfill the desire of many cinematographers for pure lens protection without a filter effect. Its only function is to keep dirt, sand or splahses away fromt the front lens.
The colorless UV filters ensure more brilliant images by blocking the unwanted UV component contained in daylight. They also can remain in front of the lens to protect it from dirt and damage.