I am still trying to figure out how to change my aperture (fstop) on my 40D. I notice that the aperture changes when I zoom in and out from the lense, but I thought I can also change it without adjusting my lens position. I used to own a Rebel XT and I know in this camera I would press A/V and that's how I can manipulate the fstops. How is it done in the 40D? My manual is no help Maybe I thought I over looked something. :meh: Any help would be very much appreciated!