I hope you have heard of Scott Bourne. He is, in my opinion, a great photography. He's successful, strong-willed and stands by his positions. Posted on Oct 31st was this a href="http://photofocus.com/2011/10/31/the-problem-with-using-filters-on-your-camera-lenses/"missive/a on using filters on your camera lenses. I'm afraid that despite my enormous respect for Mr. Bourne, I have to disagree. Sort of.
Full disclosure; I work part time in a camera store for my own pleasure and to help aspiring photographers with their questions. It's not for the enormous pay. I do recommend filters to lens customers in pretty much every situation. Let me tell you why, in consideration of Mr. Bourne's comments. Mr. Bourne argues several points, and he is factually correct but I think that these are not yes or no scenarios.
1. Filters can cause flare and loss of contrast. Yes. Please see the response section.
2. Filters can cause vignetting on wide angle lenses. Some can. See the response section.
3. There is a wide gamut of filter quality. Oh yes there is! See,, well you know where to look.
4. UV filter sales are a means of padding the sale. Sometimes but not always, engage bullshit detector when buying and see below.
5. Lens hoods provide nearly equivalent protection as a filter would. Yes, but please note the use of the term "nearly" See below.
6. A filter does not reduce cleaning requirements. True, but with explanation.
The Aforethreatened Response Section
1. Junk filters WILL cause flare and WILL cause contrast degradation. Mr. Bourne is insufficiently adamant on this point. A $20 disc of dubious optical quality, with no multi coating will reduce your image quality. To avoid this, if you do choose to buy a UV filter, buy a good one. It will not be cheap. I have used B+W filters for over 30 years and have NEVER had an issue with one. I have also bought some other brands and am not so fervent in my support of those vendors. In fairness, I have had good success with Tiffen filters made in the USA when I could not get what I wanted from B+W. Tiffen uses a unique manufacturing process that is frequently maligned by people who don't do research before opening their giant gobs, but that is where your BS detector should be used.
2. Ask the sales person if the filter will cause vignetting on the lens you are buying it for. If you get that cocked doggy head look, smile and leave because this person lacks the necessary skills to make a difference for you. If the sales person says no, ask him or her to put the filter on a lens and show you (stop the lens down, engage the depth of field preview and point at a bright source. Do the same thing with the lens wide open. Remember that many lenses vignette slightly when wide open naturally. Look for thin filter rings back to front, or those specifically indicating a narrow ring or for wide angle use. Again, great success with B+W and also remember that with ultra-wides you won't have a filter option at all because of curvature of the front element.
3. You actually do get what you pay for with good filters. And with crap filters. Go figure. Better filters will use optical glass, will be coated to prevent internal reflection and ghosting and will be mounted in brass rings to avoid having them bind to the lens threads. Screw an aluminum ring filter to a lens thread that is aluminum and tighten. Now hunt around for a thirty year old filter wrench because you're going to need that to get the filter off, because as Mr. Bourne suggests, stacking filters is not a good idea and there are filters other than UV that you will want to use such as a Neutral Density or Polarizer. Good filters will also prevent dust and grit from coming between the filter and lens. Crap filters do a poor job of filtering crap. Surprise!
4. Cheap UV filters are padding. They are very cheap and have high margin. Better quality UV filters actually create value for you, and also have lower margin to the reseller. Engage the BS detector and turn the sensitivity up and you'll decide for yourself.
5. Lens hoods are in my opinion a mandatory item, both for protection and for flare reduction. I have personally had a hornet detonate on the filter I had on a Minoita 200/2.8 back in 1986. Since I am not an entomologist, I don't know what passes for blood in these guys, and I'm pretty sure this is a rare event, but whatever that goop was, it stripped the multi coating right off the front face of that filter. The filter was effectively destroyed, but that lens was not. Since I was still not making money back then, I had saved a long time for that lens and to have had to pay service for a new front element would have been killer. Remember that service people are specialist so if anything goes in for service in the DSLR world you are looking at $200 minimum before parts. Something to think about.
6. So instead of blowing, wiping and using fluid on that front element, now you are having to do it on a significantly less expensive filter. Cleaning is part of the workflow in photography. Personally I'd rather be cleaning the front of a relatively inexpensive filter rather than the front element of an expensive lens. It's possible to pick up grit or detritus in your brush or microfiber cloth. I'd rather risk wrecking the filter than my front element.
Ultimately the decision whether or not to use a filter is yours. You could favour Mr. Bourne's position. He is an accomplished photographer with decades of experience. You could favour my position. I'm not as accomplished and certainly not as well known. You could also take input from a variety of sources and make your own choice, which by the way is what I would prefer you do. But please, if you do decide to use filters of any type, and UV filters as protection particularly, buy good stuff. It does make a difference in your success.