Its a Nikon. I bought it from Amazon, and just dropped it off at the UPS Store. Mainly I was running out of time for my return window, so I needed to make a decision.
I'm intrigued by this comment:
>I wouldn't return your 50mm based on those focus tests. To >have so little light that you needed ISO 1000 at f/1.4 isn't >giving the AF system much of a chance, and the depth of field >at f/1.4 is wafer thin. Your choice of focus target was also >far from ideal. The centre cross focusing point is also quite >large
What it suggests to me is that my real problem here is one of expectations. I do mainly portrait photography. What I want is to be able to put the focus point on the subject's eye and get a nice, sharp exposure, automatically, with at least a 50% "hit rate".
Maybe that's just not realistic with a 50mm f/1.4?
I get that the combination of my test subject and lighting were sub-optimum, but that was somewhat by design. Real world shots don't occur in idealized conditions. This process started because I noticed I was getting a very high rate of missed focus shots (maybe one in 15 or 20 being acceptable). Most of those were taken in outdoor daylight.
Is it unreasonable to expect to shoot a 50mm f/1.4 AT 1.4 and get consistent AF hits? I realize that the DOF on that lens is going to be razor thin. At the same time, I expect that if I carefully compose the shot, putting the AF target right on the subject's eye, I should get a decent hit rate. Are my expectations way off?
The way I calculate it, at a distance of five feet (at f/1.4 and with my crop sensor D7000), I should have a little over an inch of usable in-focus depth. That should give the camera a bit of margin for error to get the eyes in focus. Is there something wrong with my calculations there? Is that too narrow a DOF window for reliable AF control?
In any case, having returned the 50, I'm thinking of trying something longer (85mm? 105mm?) What I want is something that can totally wash out the backgrounds while getting a sharp hit on the subject. Maybe trying out the 50mm was doomed from the start...