[Dave Canon]

I used to always buy a UV filter for each new lens. With film, the UV or skylight filter was needed in many photographs anyway so it made sense to leave it on the camera to provide physical protection to the lens. I always bought good quality multicoated Hoya glass filters. It is very doubtful that such filters would reduce contrast or introduce flare that could be measured outside a laboratory. Remember the filters are plain glass and not curved.

Having said that I have bought two new lenses in the past 2 years both 77mm filter size which is very expensive. There is now no need for UV filtering as my DSLR already does that. One of the lenses is very wide angle so adding any filter can cause vignetting. So far I have not purchased any new filters to protect these lenses. In the 30+ years I have been using SLR's I have not yet scratched the front of a filter or lens; I always put the lens cap on other than when actually shooting. The only damage to a lens was when my then 7 year old son knocked one onto the floor which cracked the case etc. but did not scratch the lens; the filter was irrelevant in this case.

I have therefore concluded that using such filters is no longer essential but in the nice to have (if they do not cause vignetting) category. In the very unlikley event one of my lenses is accidently damaged, I will claim from my All risks insurance policy. I am not suggesting that you do or do not buy filters but that it is not a s clear cut as it used to be.