If this topic is covered elsewhere, please feel free to direct me to the thread. I want to add to my repetoire of one lens (18-55mm kit lens) for my Canon Rebel XT and I have gone around and around checking them out. I think I want a zoom lens like the Tamron 18-250mm or maybe one lens to cover the lower range and another for telephoto. I thought I liked the Tamron 24-135mm f3.5 lens, but I am not sure if it is for the smaller sensor of the Rebel XT. The 24-135mm Tamron has a $30 rebate until 4/30/07 and I could get it for $329 bottom line. The Tamron 18-250mm Tamron, which I know can be used on my camera is $499, not out of my budget, which is why I am shying away from the Canon line even though I have heard that the L series lenses are the best there are. I have found good reviews on it in several places. I can't seem to find too much information on the Tamron 18-250mm because it is so new. If there is something else out there that you think I should consider, I would be more than happy to consider it. I am not a pro, but I have a fairly good idea about things like 'fast' lenses, wide angle, telephoto, macro, apertures, etc. I don't know what an 'AF' lens is. Please point me in a good direction if you can. Thank you in advance.