I personally use an Olympus T20 flash (about $20 used) with a "filed down"
Realist (and my RBT X4 SLR). This is a lightweight compact flash that uses two
AA batteries but allows use of f8 as well as f4 on automatic, unlike most small
flashes. It is also short which gives a much better balance to the camera/flash
compared to a tall Vivitar 283 etc. One can potentially have more red eye
problems with a short flash, but I have not noticed problems. The GN is about 20
in meters at asa 100 so works for subjects at up to about 2.5 meters at f8.
Plenty for the subjects I use flash on. I do not use flash for 3d shots of large
spaces because flash lighting will always overlight foreground compared to
background. I also use this flash often for "fill flash" in marginal or uneven
light. -Linda