This was an interesting experience for me. This prompted me to repeat the whole process with a 600 mmVR. That lens did front focus about an inch wide open.
To your observations Eric, I tested for focus issues and with my 300 mm bare, it was spot on. Still a bit of a head scratcher.
Like the 300 mm, the 600 started to minimally blur at F16. The 600 was sharpest at F9. I posted my experience with the 600mm VR for those that may be interested. This has left me wandering if there would be little IQ advantage of the 600mm with 1.7 TC vs. a 500mm with a 2.0 TCIII. The later option would be more user friendly and could save bucks on a new tripod setup.
I was getting excited with the prospect of buying the 600. The 500 with 2.0 alternative prospect is holding me from pulling the trigger.
Thanks in advance to anyone who can advise me on those two options in terms of IQ.
Maybe this will take another trip to the rental store. David