Some 20 years ago I discovered photography using a just barely automatic Minolta XG-M that did not even have auto-focus. I quickly learned to use the camera in "aperture priority" (Av) -mode where I chose the desired aperture size and the camera calculated a shutter speed to go with it - and since I wanted sharp images and shallow depth of field, I always kept the camera on maximum aperture.
That XG-M is long since gone, replaced by ever more advanced and more automatic cameras. Somewhere along the way, I don't remember exactly when or why, I abandoned aperture priority. Most recently I have been using a Canon Digital Ixus 860 IS (PowerShot SD870 IS if you have not gone metric yet) in fully automatic mode. Over the last two years I have developed a complete trust in the cameras ability to chose all settings for me and I have constantly been pleased with the results.
Then, yesterday, I switched to the new Canon PowerShot S90 and all that changed. I put it in auto -mode and went out to take some test images. I pointed at the item I wanted to have in focus and pressed the shutter half way down ... and the focus-box appeared in the lower left corner of the frame, focusing on a rock in the foreground. I tried again, this time the focus box appeared in the upper right corner, focusing on a building in the distance. I scrolled trough the settings again and again but found no way to switch of this "feature" while in auto -mode.
Canon's logic is sound. If you put your camera in auto -mode then you should not have to do anything other than to point the camera in the general direction. In most cases, the camera will do a better job picking objects to focus on than an average user who does not know how to focus.
Since I knew how to focus I obviously had to start using some other mode that auto. I eventually came to realize that what I want is really aperture priority - the same mode that I so loved twenty years ago. Granted, the S90 can not produce those shallow depth of field photos with soft backgrounds, but even so, aperture priority is what I want. All those fancy "aquarium" and "portrait" modes can not change the fact that I want maximum aperture size, shortest possible shutter time and lowest possible ISO rating.
It is comforting to realize that some basic concepts stay the same even though the tools we use develop at an amazing pace.
Or perhaps I'm just getting old and sentimental.