Originally posted by walro that 3d look I'm after
The Limiteds are great for that, in particular the DA21 (too slow for you, apparently)
Originally posted by walro I'm looking for something less than 35mm that is less than f2.
Tough call. The Sigma 30 f1,4 or 20 f something come to mind, though their IQ is nowhere near the Limiteds. The 3D effect won't be there, if you don't find it with the 16-50. Both those primes are also extremely soft wide open.
Originally posted by walro I'm leaning toward the Sigma 30 1.4. Any other suggestions?
Originally posted by walro what I'm more interested in is what would have the fastest autofocus.
The Sigma is fine, but not breathtaking. I find (personal opinion) that it lacks emotion. I can always spot a shot taken with my DA21, it has that something that some lenses lack.
I think that except if you get lucky in the used market, you will need to prioritize between speed and IQ. I'm NOT saying Sigma's IQ is bad, I'm saying you ask for performances on par with your DA*55 and DA70 and you won't get it from those two lenses. The lenses that will do what you ask and currently available are the DA21 and FA31. In the used market, the FA*24, F or FA28 f2,8 (not quite as good as the DA21 but pretty darn good) and the FA20 f2.8 are your best bets.