Yes, there's definitely a huge debate among photographers as to whether to use a UV filter to protect the front of their lens(es). You certainly don't NEED a UV filter nowadays because digital camera sensors are much less UV-sensitive than traditional film. So the only reason you'd even use a UV filter would be to protect the front of your lens.
Arguments against having a filter:
You paid a lot for your lens, so you want the BEST image from your lens. When you place a filter in front of your lens, you're adding another piece of "glass" in front of your lens. You might potentially get a
slightly worse images with a cheap filter in front of your lens.
Today's lenses also have
scratch-resistant coatings, making it very difficult to scratch a lens.
Adding a filter in front of your lens also increases the chance of producing
filter flare in your images. Here's an example of lens flare that I stole from the Internet:
The image on the left has lens flare, which is due to a UV filter placed in front of the lens. The image on the right has no UV filter, which caused no lens flare.
The reason why lens flare occurs is because stray light is coming into the lens, reflects back and forth among the different lens elements, before reaching the sensor. A cheap UV filter typically has no anti-reflective coating, so stray light will first pass through the filter, reflect off the front of the lens, then get reflected back off the UV filter, before going back through the lens into the camera sensor. That's why you get the extra spots of light (lens flare) in the above photo.
Instead of using a UV filter to protect your lens, the alternative would be to use a
lens hood.
Arguments for having a filter:
It
protects the front of your lens. If you paid a whole lot of $$$$$ for your lens and if something happened to your lens, is it cheaper to replace a filter or replace a lens?
This actually happened to me once. My wife was carrying around our 70-200mm lens, which cost $1600. I walked away to buy lunch, and when I returned, I watched as the camera and lens dropped in slow motion onto the ground. When I went to pick up the camera, all that was shattered was my heart and the UV filter. The lens itself was fine. If I recall, my wife was okay, too.
Basically, the UV filter was my $80 insurance policy. In this case, all I had to do was buy a new filter, which was TONS cheaper than buying a new lens.
For lenses that aren't too expensive (kit lens?), it might not be worthwhile to add a UV filter for protection. However, the more $$$$$$ you spend on a lens, the cost-vs-benefit of a UV filter becomes more and more compelling.
Be aware, though, that not all UV filters are the same. The cheapest UV filters are just a piece of glass, and they can potentially degrade your photos and add lens flare. You'll want to look for a UV filter with
anti-reflective coating or
multi-coated UV filters. Multicoated filters *significantly* reduces the reflection off the filter, which *significantly* reduces the risk of lens flare. I would go with brand-name, multicoated UV filters for your very, very expensive lenses.
The other reason to use a UV filter is if you're gonna be taking photos in some pretty harsh conditions. Are you going to the desert, where sand will be blowing onto your lens? Or maybe you're doing whale watching on a small boat, with lots of salt water spraying onto you & your camera. So here, a UV filter helps to
protect your lens from "the elements."
Hope that helps. Sorry for the long post.
