From my earliest days with SLR cameras, I made it a point of principle to purchase a “skylight”, “daylight” or UV filter to screw to the front of any lenses I acquired. The reasoning was sound: if I accidentally clout the lens, the filter takes the strain and — hopefully — the expensive bit of optical glass remains undamaged.
As I moved to DSLR, I continued with that reasoning. Modern lens optics often have a special coating which replicates the job of a “skylight” filter, but the filter glass is optically clear anyway, and shouldn’t give any disbenefits. However, there has been increasing doubt in my mind about whether it’s worth all the extra expense at all.
Some pundits will argue that, for a relatively small amount of money, you’re buying peace of mind. It’s cheaper to replace a broken filter than to have a lens repaired, after all. Others argue that, even with quite expensive optically-corrected filters (and the filter on my Sigma 10-22mm wide anglecost nearly £50!), there may well be a one or two stop penalty in exposure. Another point is that professionals often prefer to use a lens hood as a form of protection against knocks. If you’re going to drop a camera from head height, something may well break whether you have protective filters or not, and a good robust lens hood will do the job just as easily as well as preventing some lens flare. Don’t forget, also, that when you’re not actively taking shots it’s sensible to put the lens cap on!
So, while most of my current lenses do have a UV filter, and I have tested the “one or two stop” argument—inconclusively, it has to be said—I think that in future I shall not go out of my way to purchase a “skylight” filter. I think it’s probably more prudent to spend out on some form of insurance against accidental damage! My shopping list includes some rather nice Canon lenses that come out around the four-figure mark, and I don’t think a thin bit of glass on the front will make me feel any happier if I break one of those!
This may be my last entry here for 2008. I’d like to wish my reader compliments of the season, and let’s see if I get a chance to go out and about with the camera over the next couple of weeks. See you in 2009!