Re: Question about Lenses

Lenses with lots of zoom have a reputation for slipping - changing focal length when you didn't ask it to. Some Tamron lenses especially had that reputation.

My particular lens doesn't slip noticeably, but it is quite stiff; I'm guessing that Tamron "tightened" it in order to avoid the slipping. I'm guessing that you're right, that the mechanism of the Canon lens is worn to the point that you're seeing this behavior. It should still be a good lens optically, but ultimately you'll need to decide whether this is the right lens for you.

BTW - I'm a regular at a place called the "UglyHedgehog", which is a discussion board focused (no pun intended) on photography. Within a few minutes there you will discover that people are more argumentative on various issues there than they ever are here; if there is a difference, you will find strong opinions on both sides of it, and some "facts" are not as universally true as some will claim. I got a doubler for my lens, and I was told that I would have to hand-focus everything; nobody told my camera that, and it simply keeps focusing.