For instance, the shot is determined to be one stop under for a flash main. That ambient is a result of shutterspeed being one stop under and will be so in every shot. The flash power will determine the exposure of the subject… matching the ambient results in an underexposed photograph. Increasing the flash only by one stop makes the shot correct, with the ambient still the same as before. Ambient light is controlled by the shutter speed in this case, and the flash can be moved in or out, increased or decreased in power for the subject, leaving the ambient unchanged. That is what I mean when I state that in these kind of shots, determining the ambient light at a shutter speed that will allow flash sync is one part, and then working with that aperture now becomes a function of the speedlight.

Last shot: No, not underwear… actually the back side of her jean skirt. As far as flash, it was indeed bare. If I had been working with a more liberal time frame, I may have used a Softlighter or Moonlight on the shot. In the lighting workshops we move pretty quickly on some of the shoots getting the technique down, then finessing as time permits. These shots are 4 of only 5 I shot - then the students took over and added lights and fills… It turned out far different as they went about working on it.

When you write:
“Just keep in mind that the f-stop exposure will be based on the speedlight, and the ambient will be controlled by the shutter speed”

Surely you mean that the ambient is controlled BOTH by the f-stop and the shutter speed?

The ones with the blocked sun are excellent. Great idea.