Are UV filters required for shooting film?

I've shot film for 30 years and never used one. If they were required, I'd have noticed by now.

If you want film photos of bluebells to actually look blue instead of purple then yes, UV filters are... if not necessary then at least useful for film photography. Film is sensitive to UV, digital cameras are not.

I bought a used Minolta with UV filters on both lenses. One day while shooting, I took it off half way into a roll of 200 speed film. The shots were super sketchy after that, so if you are shooting outside in bright sun with film, I would recommend it. But, that's just what I think — could be different with different film and different cameras.

The light sensitive goodies in photographic film are naturally only sensitive to ultraviolet, violet, and blue light. These blue only sensitive films yield images that sometimes appear strange. Red objects like lipstick lips and rouged cheeks reproduce dark gray, maybe even black. Photo scientist learned to add dye to the film emulsion. These change the color of silver salts forcing them to absorb green and red light. First came orthochromatic (blue & green sensitive) followed by panchromatic (red – green – blue sensitive. Such treated films never lose their sensitivity to the blue regions of the spectrum.

Under ordinary conditions, the fact that films are highly sensitive to UV, are of no consequence. This is because most camera lenses are made of glass. Glass blocks a high percentage of the UV energy. There are situations when a UV filter can be quite helpful. We are talking about the specialty of imaging objects that exhibit fluorescence when illuminated with UV light. Additionally, mounting a UV filter when doing high-altitude aerial photography. This is because, at high- altitude, the air that normally absorbs UV is scant.

In everyday photography, mounting a UV filter works to cut the distant haze present in mountain vistas. Let me add, the UV filter is not effective for distances under several miles.

In recent times the UV filter has been pushed as insurance against accidental scratching and other perils. This concept gives piece of mind however it mainly serves to line the pockets of suppliers of camera paraphernalia. Modern digital cameras are less susceptible to the effects of UV energy. These too use glass lenses plus the protective cover glass that overlays the image sensor blocks UV and IR radiation.

Let me add, good filters must be optically flat. From a technical viewpoint, making an optical flat is quite difficult. In other words, we mount filters only when the benefit outweighs the bad.