Filters from the likes of Hoya, B+W, Zeiss, Canon, and Nikon showed the least impact, while filters from brands like Tiffen showed the biggest. It’s also worse in cheap filters from no-name brands. It’s a barely noticeable effect and easily fixed in Photoshop, but it is there. Because of how the light interacts with your filter, this reduces the sharpness and contrast of your images very slightly. UV filters block a small percentage (between 0.1 and 5%) of the light that passes through them. There’s one final thing to consider about UV filters: putting any extra glass in front of your lenses affects the image quality. They’re great for protecting your lens from dust, scratches, sand, sea spray, and other small environmental hazards. It just means they don’t offer any protection from hard drops. This doesn’t mean UV filters offer no protection.
And if you drop your lens without a UV filter and it breaks, a filter wouldn’t have saved it. The lens would have been fine either way. This all means that if you drop your lens with a UV filter and the filter breaks but not the lens, all you probably did was break a filter. Even in the few cases where the UV filter might have protected the front element, the lens was dead anyway. Also, if a lens was hit hard enough that the front element was damaged, there was normally large amounts of internal damage too. Perry’s big takeaway was that the glass in UV filters was a lot weaker than the glass used in the front element of lenses so the filters break from drops that don’t even ding a lens, regardless of whether or not there’s a filter on it. Steve Perry from Backcountry Gallery drop tested a load of different lens filters and lenses and what he found was that the filters added minimal, if any, protection. Unfortunately, while the idea sounds good in theory, it doesn’t really hold out in practice. It’s a lot easier to just pick up a new filter rather than ship your lens off to-possibly-get repaired. The basic idea is that, if you drop your $2,000 lens, instead of breaking the front element of the lens, you break your $35 UV filter instead. Some camera shops are reluctant to let you walk out the door with a new lens, if you haven’t also bought a UV filter to protect it. However, this hasn’t stopped UV filters from picking up a secondary use as a protective filter for your lenses. This means you don’t need a UV filter to block UV light in order to take good photos. It doesn’t affect them the way it does older films. The thing is, modern films and digital sensors just aren’t sensitive to UV light. You can see it in this polaroid by MoominSean on Flickr. This was especially common if you were shooting somewhere there was a lot of UV light, like on a really sunny day or at high altitude. Some old photography films were very sensitive to UV light so, if you didn’t use a UV filter, you would end up with a blue haze in your photos. Think of it as sunscreen for your camera. A UV filter blocks UV light as it enters the lens.