..........not so bad!
Full capture, resized for posting (NO post editing!):
100% crop:
(EXIF data will read 600mm as the TC does not adjust the focal length. But this will be, in reality, 840mm. And with the D7100's crop factor, that an equivalent 1260mm FOV.)
FYI: My Nikkor TC is shaved, allowing it to be used on this lens.
Full capture, resized for posting (NO post editing!):
100% crop:
(EXIF data will read 600mm as the TC does not adjust the focal length. But this will be, in reality, 840mm. And with the D7100's crop factor, that an equivalent 1260mm FOV.)
FYI: My Nikkor TC is shaved, allowing it to be used on this lens.