Need help

I have a Canon Digital Rebel XT-I keep reading in the lens section and elsewhere about "crop factor" or certain cameras/crop 1.6???? What does this mean and what does it have to do with lenses. Sorry for a stupid question, just trying to learn.

"Crop factor" refers to the smaller sensor the 350D has than a traditional 35 mm camera. The 35 mm frame is 1.6x longer in either dimension than the 350D frame is 36 x 24 mm vs. 22.5 x 15 mm). This is described as a "crop" factor; what it comes down to is that a lens on a 350D will take a picture of the same field of view as a lens with a focal length 1.6x longer will on a 35 mm camera. As you're not used to 35 mm cameras, don't worry about it. Learn how your lense(es) work for you and your camera. I have both full frame and 1.6x crop cameras; I spend less time worrying about the "crop" than how to get the picture I want regardless of which lens I may use on which camera. There's a thread collecting "crop factor" posts, and there are a lot of them.