Quite why it should be that the use of a UV filter for lens protection should create such heated debate amongst some photographers is beyond me. The theory is that image quality will be degraded by a 'cheap' piece of glass placed in front of the lens. yet often those who argue against the use of a UV filter happily place resin filters in front of their lenses to create effects (e.g. Lee Big Stoppers to allow long exposures so they can take yet another milky sea photo like the thousands that have gone before), or use polarisers.
As a clumsy person who has twice managed to allow his camera to topple lens first into mud when it was on a low set tripod, and who habitually pokes his fingers inside lens hoods to remove lens caps that have already been removed, I tend to fit my lenses with filters for physical protection.
A while back I had been using one of my lenses sans filter as I'd put it on a new lens while I waited for another filter to turn up. Looking at the shots I thought they looked sharper and more contrasty than usual so I checked the lens. Blow me if I hadn't been using it with the filter on!
Only once have I noticed any adverse effect on image quality being caused by a filter, and that was a cheap UV filter on my Sigma 150-500. The out of focus areas took on a diagonal banding. As this lens has a huge hood I have managed quite well without the filter. So my advice is this: don't ask anyone if you should use a UV filter for lens protection, try it and see if it makes things worse or not, then do what makes you happiest.
Here's a quick quiz. Two shots, converted straight to jpeg from RAW with no processing at 100%. One taken with a cheap UV filter in place the other without. OK, I hand held so it's not strictly a fair comparison if you're a pixel peeper - but that's how I shoot 99% of the time, so it suits me. Answers on a postcard please!
