Originally posted by aleonx3 Aristophanes, you are right about that... However, Lowspark86 is referring to F1.4 gives bright viewfinder, and therefore, should be easier to get focus locked in dim light than slower lens.
Shallower DOF will always lead to poorer AF performance. A razor thin lock is difficult unless the frame is perpetually face to lens. Hardly candid. And if you're in portrait mode, don't you want more contrast, better res, etc.?
Most weddings I have attended the photog has a constant big, soft, flash to get over that problem.
Besides, it sounds like the DA 70 focused just fine.