Then I took it out for a quick test -- usual subject, a mud-brick wall shot on a tripod. Result: the lens is softer than the damaged F* 300 f4.5 that I just returned. I am baffled how this could be. Except for just a little typical dust, the optics look fine. The F version that I just returned had the rear element covered in spots of something.
I cannot believe that I could have gotten three bad ones in a row. What a disappointment.
The test was done in a hurry, but it has become my standard testing procedure and I can do it in my sleep.
The light was different -- evening, vs. morning for the images from the F lens. This should have made no difference, since the wall faces north and is nearly always in shade. Still, I may repeat the test Saturday morning.
Maybe it is the difference between attaching the tripod in the middle of the lens/camera assembly (F* 300) vs. having to attach the tripod to the camera (FA* 300). At f4.5, though, I was shooting at 1/500 of a second. So I cannot see how the tripod mount could have made the difference.
What frustration.
Joe
