BJL, I am not completely up on autofocus, owning or considering none. But how does the camera auto focus where I want it to focus, especially when there is nothing there to focus on?
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First note: either it works, or a vast number of very successful and skilled photographers are taking a lot of poorly images and yet no-one has noticed! Perhaps you should ask someone with more authority, like Michael, if he thinks that AF works at least a good proporton of the time.
Anyway, on to "autofocus for flat-earthers":
AF is usually achieved by either
1) Focusing on the subject at one of multiple AF points spread over the field of view, with AF point manually selectable in cases where the automatic procedure chooses the wrong one.
2) pointing an AF point at the desired subject and then activating AF at that point, usually with a partial press on the shutter (one must likewise point at an off-center subject with a manual focus camera if one wishes to use standard focusing aids.)
As Jonathan Weinke explains at his Visual Vacations website, using off-center AF points is better than re-orienting the camera towards an off-center subject to focus, because that "pointing" procedure ends up with the plane of focus slightly behind the subject. (Focus is roughly on a plane, not a sphere, so off-center subjects are in sharp focus at a greater distance from the camera than the focus distance.)
In cases where the AF algorithms fail, like lack of suitable lines for the AF detector to work with, manual focus is still available, and indicators in the cameras let you know that AF has not been achieved. My E-1 is usually in manual focus mode, but with the option to active AF by pressing the AEL button, so I have both options easily at hand. I end up using the "AF button" most of the time, but MF more often when quite close to the subject.
I will repeat, for those who seem to be trenchantly ignoring this point:
All modern automated DSLR's also offer every possible degree of manual operation.And with Canon and Olympus lenses at least, manual over-ride of AF is quick, easy and safe. Some other lenses need to be switched to MF mode, or you risk damaging the AF motor when you turn the focus ring.
P. S. Howard, it is amusing that you worry about the cost of adding autofocus when we are discussing a $5,000 camera. Perhaps you should write to Canon, Nikon, Olympus, Pentax, Sony etc. notifying them of the brilliant cost-cutting proposal of omitting AF in future models.