Originally posted by userage They are roughly the same price and I want to buy one but I'm not sure which to go for.
Does the Auto-aperture just mean I can use Av mode and change the aperture through the camera?
Which would you guys prefer ? :S
I would buy the 'A1.7'. Practically speaking, they're quite similar from f1.7/1.8 and up, and quite sharp (from what I hear), and as others have said, you lose half a stop, which means either +50% shutter speed (for instance 1/30 -> 1/20) or an equivalent change in ISO, but it's hard to focus at f1.4 (or f1.7) lens well enough to make frequent use of of the extra glass. The extra compatibility, however, is worth a lot. In-camera aperture control (and the correspondingly instant exposure calculations) are totally worth it. It also makes it much more compatible with flashes.
(I own M1.7, M28, A28, and FA1.7)