In the film days, a UV Filter’s function was, as the name suggests, to block out ultra violet light rays from hitting the film and degrading image quality, writes Andrew James. As DSLRs have an internal filter that does this, the need for a UV filter on the lens has significantly diminished.
However, a case for the use of a UV on the front of a lens can be made when it comes to protection. Certainly it will prevent the front element of an expensive lens from getting scratched and it might, in some circumstances, help prevent a lens from smashing if it was dropped.
But could it degrade image quality?
Yes, to some extent it has to, simply because you are potentially putting poorer glass in front of your expensive and hopefully, high quality lens glass. A cheap UV filter on any lens is an absolute no-no. They can cause a shift in white balance, although this is correctable if you shoot raw, and sometimes they will cause unwanted flare simply because there is extra glass for the light to bounce around in.
By using a UV filter with a cheap lens you degrade the quality of images from that lens even further and by using one with an expensive lens you could take the edge of its performance. If you are going to use one then pay more money for a quality one and check it by holding it over a white piece of paper in daylight and looking for any colour shift.
I try my best to protect the front of my lenses and will use a lens hood if I am shooting somewhere there is vegetation that might scratch the lens or I always put the lens cap back on when the camera is being transported in my bag. However, if I am shooting somewhere like beach for a few days where there is like to be a lot of windblown sand then I do have a Tiffen Hi-Trans Titanium Multi-Coated Ultra Clear Filter than I can screw onto the lens for some added protection. It’s not a cheap option with the 77mm screw thread one I have costing around £70+. Using this I haven’t honestly noticed any discernible drop in image quality but I still refuse to keep it attached all of the time, just in case!
Ultimately, a UV filter is nothing more than an expensive lens protector. Taking care of your equipment to prevent scratches to the lens is easily done in other ways, so unless you already have one, it’s not something I’d recommend spending your hard-earned cash on unless you intend to endure a lot of time photographing while concealed in a hawthorn bush!