Thank you, Waddizzle. Makes sense. But, have gone through the manual, and find nothing related to this. The index shows "Q" being dealt with on pages 51 and 85. BTW, with all the different languages covered in the one manual, that index ain't easy to find - in English. I don't find a separate listing for "Disable" or "Disabling".
Actually, pushing the Q *does* take me to the image quality screen, but that's it. The control knob works in that screen.
It's looking like I can probably learn to live with this, as the shutter speed and f-stop are the only things I ever fiddle with, anyway. Well, occasionally ISO, but there's a separate button for that. In manual mode, it does let me set the shutter speed, and holding down the "Av" button whilst scrolling does let me adjust the f-stop, so, if I hold the Ikelite underwater housing between my legs, I might be able to work that button and knob at the same time. I see that switching to Av mode also allows me to change f-stops, but when I switch back to M, it reverts to the previously set f-stop that was in the M mode before changing it in Av mode.
Was trying to switch to "AI Servo" so as to have constant autofocus available with my new "back button focus" capabilities, but I guess I can go on living without that feature. My previous Rebel T2i didn't have the option of using back button focus.
I see that one of the few camera "fixit places" left is just a couple of miles away in Lauderdale by the Sea. Forty bucks (cash) just to take a look, but maybe I'll spring for it. 🙂
