Kam,
thanks for the comments..
You can adjust the ISO in 1/3 increment on your 50D but you need to do it in the creative modes (AV, TV, M). Please check your manual for more information.
I've beenusing my 40D since Oct. 2007 and I still checkits manual from time to time. I wantto make sure thatI still know the camera inside out.
If you're new to photographymany thingsin the manual can be confusing, please ask here and a lot of us will gladly help you.