[Rover]

The vignetting is - again - nuts, it's like Leica territory or something. Overall this lens doesn't seem very practical between all the alternatives. The big question mark is whether the f/4 IS lens does fall apart at 50 MP - then, of course, the hapless 5DSR users have no other (brand name) high quality option.

 

Thankfully this new lens did not trigger the G.A.S. in my case... I know where my loyalties lie.