Originally posted by ZombieArmy Lots of forms of UV are blocked by lens glass alone,
NOT so. UV energy is classified in regions- UVA (aka, near UV) in the 320-400nm range (humans see about 400-700nm), UV B, 280-320nm (the UV that can give sun tans and sun burn) and UV C (200-280nm, aka, biocidal UV, VERY bad for sunbathing and eye health). Below UV are X-Rays then Gamma Rays. As you can see by the attached graph, which ends where the visible spectrum starts, camera lenses can transmit UV down to 310-320nm. Film could be sensitive down to about 360nm (Silver is sensitive to blue light without adding any dye sensitizers), but CMOS sensors are not. So in the film days, the UV filters made a difference. Unless the sensor is designed for UV imaging, UV energy will no longer effect an exposure, however, the reflected UV energy, if high enough, could be reflected into the eye, and cause damage (why you do not look directly at the sun and certainly not during a solar eclipse, when the pupil is dilated open due to the visible light intensity being low, but the UV energy is still high!). Also, any effects of the filter can now be seen immediately in the resulting recorded image.