Max f/4 Lens + TTL Flash
I took a flash photography class at Helix and the instructor (Will Crockett) gave several tips on getting proper TTL flash exposures. One point he made was that the best TTL "pre flash" data is had with lenses f/2.8 & faster. I understand his point that TTL is all about the feedback it gets from the preflash and I understand why you'd want the maximum aperture (F/2.8 = more preflash data back to the camera than f/4).
I've heard many people say that 1/60th @ f/5.6 is generally a "good" exposure when using TTL indoors.
My questions are:
1) If you use a f/2.8 lens for a TTL flash shot but have your camera set at 1/60th @ f/5.6 does the camera stop the lens down to f/2.8 for the preflash before shooting the shot at f/5.6?
2) What kind of results have others gotten with shooting indoor TTL flash shots with a max f/4 lens (such as a Canon 70-200 f/4)?
Thanks for your input!