At 14 oz. this lens is very light and I liked the operation except that there was a noticable increase in force needed to zoom from about 85mm to 135mm. The barrel turned easily from 18mm to 85mm and 135 to 200mm. It also zoomed back smoothly.The lens offers a good bang for the buck, but I found the binding of the zoom mechanism distracting. I called Sigma and they offered to take it in and examine the lense, but said that some lenses will bind through some of the travel of the cam. Their customer service was easy to contact and helpful.If price is a issue, this is a good choice. Otherwise, go for the Canon70-200 F2.8L IS USM.