Upload & Sell: Off
Kevin, must have been reading upside down, even looked at the photosynthesis page to check its specs and was still reading it upside down on that page 900mm is of course still very long. Was your test shot that was soft that far away, that may be hard to get sharp in the best of circumstances, with all the heat, atmospheric pollution etc. in the way. Maybe try a less challenging shot to verify the lens is good.
It's a 600mm, so 900 on Dx. Either way, it's hard. My tripod can take the weight, the head is just over its limit. It takes 8 seconds on average for the lens to stabilize. It's a beast of a lens. Even comes with a close up lens diopter so the lens can focus down to about 13 feet. I did a test shot on a radio tower about 3 miles away, heat distortion was heavy...