OK, I think I understand how to do this, but I want to make sure that what I am thinking is really what I should be
I want to take shots outside, and I want the sky to be underexposed.
I get a exposure reading for the sky, say f16 1/125
adjust flash to expose the subject properly
then change the shutter speed to say 1/250
that should underexpose the sky by one stop, am I correct
Still very new to flash photography, so any help would be appreciated, but my understanding is aperture changes subject, shutter changes background
I hope I am starting to understand this.