So the idea for running at f8 with an APS-C unit is to maximize lens performance under controlled conditions. The lower/faster iso settings produce less noise in the final product, so again under controlled conditions the idea is to generate a studio that allows taking the shot at iso100 or iso200 or as camera performance dictates.
I may give a fast prime a try, with the idea of running at f4 to minimize my light requirements as I learn the craft and develop my equipment. I would benefit from the sofer focus on the background as well. I appreciate the recommendations for buying a quality strobe setup, but I'm still reeling from the purchase of a quality camera hence my home-built softbox. I did upgrade to 1600 watts of 5500k cfl lights with some marked improvement in exposure settings.
So for my situation, I want to run at f8, lower with a fast prime, at a low iso, but all this only so far as I can produce enough light with my Red-Green studio, and will sacarafice the lens sweet-spot aperature for better exposure as needed, along with iso settings up to 400 if need be.
Thanks for putting these setting recommendations into perspective for me!