If you're shooting fast action sports or birds then it could be an issue, but it's not like it's 3x as slow as the 70-300mm which costs over twice the price. So far, everyone that I have seen writing about their own views of the lens says it's great.
Has anyone here ever used this.?
My son has a 30D and is thinking about buying this lens.
The reviews look good on it from what I can find. The only knock being that it doesn't have USM and is a little slow to auto focus in low light.
Is the no USM anything to worry about?