Just a quick post today to say that version 3 of my auto bracketing script (Canon Magic Lantern based) can be downloaded from the link on the right.
In addition to tiding some things up in the code, this version has the handy facility of reporting the number of focus brackets required to cover from the current focus point, which must be less than the hyperfocal distance (HFD), to the HFD.
This is a useful, realtime feedback when you are about to run the script, as the number of brackets gets very large with long focal lengths. For example, the number of focus brackets to cover the full range of a 24-105mm lens, at 105mm and F/14, from the macro end to the HFD is some 63 and at F/4 some 110!
IMHO you really don't want to landscape focus stack beyond, say, 10 brackets. Thus, the guidance: is restrict landscape focus stacking to focal lengths, say, less than 24mm, ie wide not long lenses.