External Flash (SB-400 shown above)
External flash is the way to go if you want to integrate flash into
your close-up and macro work. Flash for focus stacking would
require the unit to flash one time for every photo layer, so that
might require some careful monitoring to keep everything even. I
have never tried it. These years I really am off flash and into
natural lighting.
Using less flash is better than more, IMO, so although I have a
bunch of flash units, my tiny SB-400 (@ $200) is very lightweight,
uses only two AA batteries, and gives me more light than I need. In
fact, I have a bunch of diffusers to tone it down and so on. I also
have various arms and other rigs that mount off the tripod and
work with the hot shoe on my camera to extend the light away
from the camera above or to the side.
I also have a couple SB-600s, an SB-900, and older flash units.
Since I don’t really use flash except for snapshots at parties, I