[quote]Two other lens manufacturers to look at are Sigma and Tokina (As far as I know, their lenses are still largely metal). I tend to rate the aftermarket mfrs in this order of quality: Sigma, Tokina, Tamron. I generally won’t bother with the others. Sigma also makes SLR cameras using the Foveon sensors. The Sigma EX tends to have pretty good build quality. My Sigma 50-500EX,APO is all metal (not a light lens) and has held up for several years (more than 8). It is getting to the point that I may need to get it cleaned though. I got my S.O. a Tokina 80-400ATX which is virtually all metal. My sister is using a Nikon body with older Nikon lenses and Tamron lenses. I have noticed that Nikon is going plastic.. and I am not too happy about their lens quality these days. They have decided to try to fix lens problems in the camera w/ software vs a proper lens build. Canon tends to have good lenses.. but very pricey.
[/quote]

Thanks. I did do a comparison between the Sigma 18-50/2.8, the Tamron 17-55/2.8, and the Canon 17-55/2.8

Canon seemed to be good. Tamron seemed the sharper at versus Sigma, especially at 2.8. I ended up picking up the Tamron because it was cheaper that all 3.

Canon 17-55 has slightly better construction (though still plasticy) but also has the ultrasonic focusing and image stabilizer, the other two don’t. Tamron’s drawbacks are (1) focusing is loud (2) the zoom works in the reverse direction of all other canon lenses. Also, none of the lenses are weatherproof…The tamron is the worst…Fortunately, the tamron includes a 6 year warranty, and if dust gets caught in the inside of the lenses, they clean it out for you under warranty