The auto iris on our F355 over-exposes the picture by at least half a stop. Where can we adjust this on the camera to get it closer to a proper exposure?

And please don't tell me "the iris ring on the lens." :)

You can set this function in the Paint menu under "A. Iris".

You should also be able to just turn the menu knob to adjust the Auto iris with + or -. If this is not set to on you can setup the menu knob to adjust the Auto Iris in the Maintenence menu under Cam Config.

On the 350 you can adjust the auto exposure by turning the menu knob left and right when the menu is off. I know this because I hit the damn thing all the time, and "AE+0.5" or "AE+1.0" comes up in the center of the viewfinder!

May I ask what you're auto-irising for? I have a hard time getting good pictures that way, but I will admit it'd save me once in a while if I'd use it.