Crop factor question

I thought I'd ask this here since a lot of the members are friendly and knowledgeable. I thought I understood the crop factor of my Canon 40D but I guess I don't as I got my hand slapped in a flickr discussion.

I have a Canon 28-135 lens and a Canon EF-S 10-22 lens among others. From what I understand, on a non EF-S lens, at 28mm, the camera crops in 1.6 cutting off the outer edges. I would always use this math: 28x1.6=44.8. I always though that the real world focal distance was 44.8.

Am I mistaken?

If I shoot a Canon EF-S 17-55 f/2.8 @ 55mm, the actual focal distance is 55, but if I shoot a Canon EF 24-105 f/4L @ 55, the actual focal distance is 88?

The crop factor would be a full frame body vs a crop camera comparison and has nothing to do with the lens. A 55mm lens is a 55mm lens regardless if it is EF-S or not.

If you do not own or use a full frame camera, it really is useless information for the most part.

Your 28x1.6 would be equal to the field of view of a 44.8mm on a full frame camera, not counting for small variations from lens to lens.

You would apply the same focal multiplier to an EF or an EF-S lens. So a 17-55 f/2.8 IS EF-S lens would equate to a 27-88mm lens on a full frame camera.

Focal length is an intrinsic property of the lens, it has nothing to do with the size of the image circle or of the sensor behind the lens. I think you may be under the mistaken impression that for EF-S lenses, Canon somehow alters the focal length numbers to compensate for the fact that they are used on a crop sensor - that is not the case. 55mm on an EF lens is the same as 55mm on an EF-S lens - both would give identical framing on an APS-C camera, and both would give a wider angle of view, but identical framing on a FF camera (if the EF-S Lens could be mounted on one, that is).

I am just learing photography myself. I am not much of a fan of Wikipedia, but the illistration on the right side of this page makes sense to me. Hope it's ok to add links on this site.

http://en.wikipedia.org/wiki/Crop_factor

I think I understand now, my thinking was correct, I just wasn't spelling it out correctly verbally. I read the wiki article as well as the article on this site and believe I better understand it. Thanks everyone.