Originally posted by SpecialK Protection = lens hood when shooting, lens cap when not.
UV filter = saleman's commission.
"Infared" = infrared :-)
I use filters mainly because during each shoot, I usually have to wipe the front element of the lens I am using at least once. I'd much rather consistently wipe an under $50 filter than an $800 item. I also often bump my forearm into the front of the lens, which makes a messy arm print. Takes forever to wipe off the front element of a lens with that on it.
I often shoot near the ocean, which has tons of sand and sea spray. Don't want that on the front of a lens, especially a Nikon lens I have that has a rotating front glass, where sand can actually wedge under the lens lip and around the glass edge if it's not protected.
Lens hoods are garbage unless you have strong light sources in front of or to the sides of the image you are shooting. If you are outdoors and shoot away from the sun, a lens hood is rendered useless. Also, try rotating your polarizers with a lens hood attached. I hate how they take up bulk inside my camera bag. Even in reverse, they make the lens more bulbous and harder to fit in the bag's pockets. I only use them when outdoors and I am shooting in different directions.
UV filter on each lens is for convenience and protection is a must for me.