I am trying to decide on the 50 f/1.4 or the 50 f/2.5 Macro.
Is this typical of the distortion of the 50 f/1.4?
http://www.pbase.com/image/24157481
From what I read on photozone.de the macro has no distortions or vignetting
wide open and the f/1.4 does. I assume that is why it has a higher optical
rating. But this photo with the f/1.4 was at f/13 (hardly wide open) and to
me there is a lot of distortion. Is it the lens or something about the shot?
The tradeoff between the lenses appears to be:
 The macro is slower to focus, cannot work in as low a light, but has no
distortion or vignetting.
 The f/1.4 can focus faster, work in lower light, and give more blur, but
has noticable distortion.
How wide an aperture do you need to blur the background for a given focal
length? What is the relationship of subject distance, focal length and
aperture? When would a f/1.4 be needed to blur a backround where the 2.5
wouldn't cut it?
How important is AF speed on a 50mm (I've never had an AF SLR)? I can see
the need for fast AF for a 70-200mm zoom since that is the lens I have used
(manual version) to shoot horses etc. I have normally used my manual focus
50mm to shoot static subjects so I really don't know the value of fast AF at
that focal length. Do people use 50mm for alot of action shots? Do people
use macro lenses of different focal lengths for compositonal flexability
(because of wider FOV) or just because they cannot afford a 100mm? I am
already planning on getting a 100mm 1:1 macro lens so I will have macro
capability.

TIA
Chris