e-300 focus and exposure lock with half-press

[hartcons]

As I understand it, my e-300 locks *both* exposure and focus with a half-press and I haven't found any way to change it. This seems to make it difficult to use auto-focus for hyperfocal focusing (focusing approximately one-third of the way into a landscape shot) or even for focus and re-compose if you move very much when you re-compose. You can use the AEL button I suppose (and in the menus you can set the AEL button to automatically use spot metering regardless of the current metering setting) but you have to hold the AEL button down the whole time (vs. click on and click off).

Is there some advantage to locking both focus and exposure at the same time that I'm missing?