Example: Isolation versus Back-fill
Prepared 2007-07-07 by Bill Claff

D70 with 70-180mm micro-nikkor

Image arrangement:

@70mm f/11 1/250s ISO 1400

@180mm f/16 1/250s ISO 200 2 SB-R200s

@180mm f/16 1/250s ISO 200 2 SB-R200s and 1 SB-800

Top image shows even ambient lighting.

Bottom left is "normal" flash on just the subject.
Note "black" background isolation.

Bottom right is flash on subject and flash on the background.
Note the "normal" appearance with no black background isolation.
Still isolated by Depth Of Field (DOF).