Pre-focusing

I just learned something practical from a discussion under a tOP article.
The article had mentioned how the author preferred to have the autofocus function separated from the shutter button. Somebody asked why, and somebody else said:

"There are many situations where you want to pre-focus the camera and use the same focus point for several pictures. If the shutter button focuses, then you lose the locked focus after each shot. Worse, you have to wait for the camera to focus every time you hit the button."

So I asked:
I never really thought about separating the autofocus function from the shutter button, but I'd like to try it. Does anybody know if I can do it with the Panasonic G1 or GF1?

And then continued:
(Why do they keep saying "RTFM" to me?) [Note: "Read The Friendly Manual".]
...OK, in the custom menu, if you set AF/AE lock to AF, and the AF/AE LOCK HOLD to On, then the AF lock button will hold the focus through several pictures until you press it again. (Or until the camera is turned off.)

Can also be helpful for faster operation, doing "zone focus", if you have the depth of field for it.

... Come to think of it, this also makes it easier to prefocus on a developing situation, since you no longer have to carefully keep the shutter button half-pressed, trying not to fully press it prematurely.

The more I think about it, the better I like this setting. It is rather accidental if the focus point is exactly in the center of my composition, and if I can set it with a separate button, then the shutter button operates much faster, and I don't have to think about holding while re-composing (or waiting).

One small danger does present itself: you might forget to turn off the focus-lock, and not notice (in a busy situation) that the camera does not focus before exposure. One would have to pay a little attention to that until getting used to it.

... Of course one can set the camera to not lock the focus after one picture, and yet use the AF button. (Hmmm, I'd like a setting where one press locks it for one picture, and two presses (or a long one) locks it until you press it again!)

(Hmm, I should look at the Function button (arrow down), I have never used that for much on most cameras, maybe it can expand the options. Update: sadly no, it only has a short range of pretty useless options, the most interesting to me is setting file quality.)
Note: does anybody know a way to get AE (auto-exposure) lock on the G1/GF1, once you have set the AE/AF button to AF only?

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On a different but related subject: if I ran a camera company, I'd make a high quality compact camera with a small sensor, 28mm-e lens, 4.0 aperture, and no autofocus, just fix-focus. Even with a very good lens, it would be cheap, simple, and dead-fast to react. Should be popular.

What they at least should do is make it simple to set the camera to fix-focus for max dept-of-field.

... Please note that the bulk of this post (pre-focusing) applies equally well to situations where you do need accurate focus, but you have either good time to do it (more than three seconds), or almost no time (less than half a second).

... Actually, come to think about it, it's getting harder for me to imagine many situations where focusing being set by the shutter button is really an advantage. When you have to take a series of pictures where the focus point is off-center, it's a bit of a p.i.t.a. to got "fetch" it between each shot. (Other possibilities are manual focus or "follow-focus" or face recognition. But I think this button and lock is an excellent solution which deserves to be better known.)