hpulley wrote in post #10709968
Canon introduced shutter priority first as many consumers couldn't understand apertures that well, or so they said. It was simpler for them to think of 1/focal_length or just "use about 1/500 hand held" rather than setting the aperture where small numbers are really bigger apertures...
When I bought my first Canon, which happened to be the Canon EF (which was Canons first camera which used all the FD lenses and had automatic exposure built-in), Canon claimed that automatic aperture (Tv) was better than automatic time (Av) in a camera, since when shooting fast moving things, the shutter speed affected the outcome of the image more than the aperture did. If the subject wasn't moving, you had the time to adjust the exposure time to get the aperture you wanted (there were scales which showed both the aperture and shutter speed in the viewfinder of the EF).
Another reason for Canon to implement Tv first was probably because they could. Many other manufacturers at that time didn't have such an advanced lens mount as the Canon FD, hence they simply didn't have the mechanics to handle automatic aperture.
Did anyone ever shoot with the Canon F-1 equipped with the Servo EE finder and motor drive MD? Or even the MF motor? For anything else than automated registration, where you didn't carry the camera around, that is.
You can have a look here
, if you don't know what they looked like.
To see the Canon EF, you can just look at the picture to the left of my post.
I'm not ashamed to say that when I just shoot snapshots with my 7D, I often use the P mode. It gives reasonable combinations of shutter speed and aperture, and I can focus on - focus.
Remember that when you use One Shot AF and evaluative metering, you always have exposure lock, whether you like it or not. If you use only AF-ON to focus, you can also imply AE lock on half-press all the time, if you like. The cameras have a C.Fn for that.