I think f2.0 - that should send some people in a fit ;)
Here's a story to chew on - especially those of you who have been shooting for over 15 years.
Interestingly I went to a "lighting seminar" (aka - check out this new system we have an buy one) at a store. It wasn't anything special, just some off brand with a direct wireless set-up for control.
We were all taking test shots and when it was my turn I started giving the set-up fits - massive blow outs, out of sync, etc. I was one of only 2 who had Nikons and the other had a D90 with the 18-105. I just brought a 50mm f1.4. Everyone was saying Nikon stinks this, Nikon inadequate that and doing those usual Cannon jabs since all of their's worked fine. Couldn't figure it out. Finely a gal came up with a 85mm 1.2 and again everything was blown out. It was the F-stop that was messing with the system that supposedly compensated for it. Her and I were shooting at f1.4-2.0. Everyone else there never shot below 5.6-11.
So what is the point of this whole thing? Not even the employees had tested it below 2.8. Then the lady and I started getting raspberries about not shooting at F8 and actually had to defend shooting below 2.8! That really took me back a bit.
Now in my head, we were at 8ft so we had about just under 1ft of DOF with a slender model so f1.4-f2 would get her in focus and throw the ugly backdrop into a blur which was about 3ft behind her. At F8 the DOF is almost 4 feet and everyone else's photos had a sharp model and the transition-less sharp jaggedly edges of color of the backdrop. They were all chimping at their screens how good it looked and all I saw was the background and thinking blahhhh yawn.
What got me was one of the staff (who I somewhat know & is about my age) who also has a full time photography business, was trying to teach me about F8. He was trying to be helpful and I just found it interesting listening to him and his pointers why F8. Now he started lenses are not sharp below F8 and how he learned this from shooting since after high-school with 35mm, medium format, now Canon bla bla bla.
Now I know I tend to shoot outside most "how to" books but what got me was him and I were about the same age, but started shooting about 10 years after him. He came in with film, and I came in with 10mp sensors being the new hot-dog. I also came in when all of the lenses were just being updated and CAs, and MTF had improved greatly.
It made me wonder if the time I came into photography with all the updates to lenses & digital has had a greater impact on my style and preference to shooting wide open than if I came into it 5-10 years earlier. I'm not too sure - but the idea that a professional shot must be at F8-F11 really seems foreign to me. Maybe I have processed that info in an odd direction?
Any thoughts? (BTW sorry for the long read) :)