And is it common practice to put a simple UV filter on a L lens to protect it, or is that like taking the engine out of a Ferrari and replacing it with a civic just in case you get in a wreck?
If so, what are some decent filter brands? I think I have B+W filters on my cheaper lenses.
I don't know about the weather sealing of the 35mm f/1.4L. However, I use UV or clear filters on all of my Canon lenses. I highly recommend them in Alaska, as the weather there can be cold, wet, and miserable. When you are out in the field, the last thing you want to worry about is whether you should have put a protective filter on your $1,500 lens. As for brands, I have B+W and one good quality Hoya. I recommend them both, although the B+W filters have brass frames and seem more solid.