UV (Ultraviolet) filters are very controversial in photographic circles (as if it were a life & death decision). In film photography UV filters are a no-brainer, film is sensitive to UV light, but digital sensors are all but impervious to UV rays. I am NOT a techie, gear-head or scientist so I can’t give you all the technical reasons this is so. Suffice it to say: it pretty much is.
The two camps, those for and those against, each make good arguments—so in the end it’s up to you (the photographer) to make your own decision. But that’s always the case with photography isn’t it? I know you’re dying of suspense wondering if I use them or don’t use them. Drumroll please: the answer is it depends.
Photographers who use them often cite prophylactic (protective) reasons. They use them to protect the expensive front lens element from damage. I think using your lens hood against the occasional knock or bump offers more protection than a UV filter. But when it comes to protection against the elements I opt for a UV or protective filter. Sand is silicon-based and can easily scratch glass (even good glass) and dust and water can migrate into your lens’ internal workings.
So if I’m photographing in harsh conditions such as: jungles; rainforests; blowing sand, dust or snow; saltwater or rain I use a UV (protective) filter. I also use a Storm Jacket rain cover for my camera body and lens (both are cheap insurance against damage). I shoot with pro-level cameras and lenses that are heavily weather-sealed but that’s NEVER a guarantee against damage. I’ve known more than one professional photographer who has fried his electronic camera gear in harsh elements thinking it wouldn’t happen.
Canon is very specific about their weather-sealed L-glass: Weather-sealing is not complete without a protective filter covering the front lens element (I for one believe them). Most L-glass comes with a rubber O-ring that effectively seals the lens/body connection but that doesn’t offer any protection for the front of the lens. The addition of a UV (protective) filter helps to solve that problem. So what are the arguments for not using a UV (protective) filter on your expensive lenses? It boils down to just one argument really: image degradation (loss of image quality).
There is some merit to this argument. Click here for more good information on the subject. Image sharpness appears not to be affected but color rendition and lens flaring may be negatively impacted (to a very slight degree). So the argument is: why would you (intentionally) compromise the image quality of a very expensive high-quality lens with a comparatively cheap piece of inferior glass? The common sense answer is: you wouldn’t. And yet sometimes I do. Back to my original answer when asked if I do or don’t use a UV (protective) filter—it depends.
If shooting in a studio or indoor location I wouldn’t think of it (there would be no need). If I’m shooting outdoors in good weather I probably wouldn’t use one either. But being a full-time wildlife, landscape and travel photographer I often find myself in harsh shooting environments (great for dramatic photos but tough on sensitive gear). Just like I would use prophylactic protection for safe sex I also use prophylactic protection for safe photography in risky shooting situations. That protection includes: UV (protective) filters and Storm Jacket rain covers.
When using protection the tradeoffs or compromises are minimal when compared to the cost of my equipment. No loss of sharpness and only the possibility of color rendition issues (I’ve never experienced them) which could easily be corrected in post-processing. Lens flare can be avoided by paying attention to your shooting position relative to the sun. It’s not worth the risk (to me) to put my equipment in harm’s way when I don’t have to. To each his own. The decision is yours to make and I hope this post may prove useful.