I got to try out Canon 70-200mm/4 NON-IS today

[Compaq]

And it was awesome. At f/4 and 200mm I had to bump the ISO to 800 to get a shutter speed of 1/500th of a second for some action shots of ducks. I'm worried my 40D won't handle ISO-800 very well, especially if I'm left having to crop some. Flying, incoming ducks landing was fun to shot, and the AF was pretty darn quick. The lens is inexpensive as well, but I can see the faster f/2.8 being handy. This was on a sunny day / overcast day.

One day, perhaps.... one day........

 

[Overread19]

The 40D should be fine with ISO 800 on a properly exposed photo - just make sure you're not underexposing and run some good noise reduction over the shots and they should come out good.

 

[Compaq]

Thanks, that's nice to know. I could do a ISO test myself, and not live off from sayings from others I just can't afford anything else than the f/4 non-is, but it's a great lens nonetheless.