I basically used aperture priority and ISO adjustments sufficiently high to match the ambient light, while at the same time maintaining a shutter speed of 1/250th second. The flash was set at Auto TTL. If any part of the flower was then overexposed because of the flash, I would have given some negative compensation to the flash. But as I recall it wasn't necessary.
The lens used is an old Nikkor 105mm micro lens, with an aperture ring on the barrel of the lens. I tried to keep thing simple by either using F4 or F8.
The full set of 17 images is at this link:
Five of my favorites of this set are below: