9 out of 10 points and recommendedLight weight, Good Optical Performance, Improved ISCould be cheaper!
I bought this lens because I have always wanted a DO lens but the first version of the 400mm DO was a little disappointing - based on online reviews. So when the Mk II was annnounced towards the end of 2014, I eagerly waited for some positive reviews. After a long wait, I managed to come across 3 positive reviews of this new lens.reviewed October 4th, 2015
When I got the lens, I tested it against my 300mm f2.8 II. Optically, I feel they are very similar. Performance with the 1.4X TC was very good - both AF and sharpness were very good. With the 2X TC, AF was noticeably slower but in good light, it was still reasonably fast. I had to do a bit of AF micro adjustment before I could consistently get accurate AF and sharp images. Yes, even with the 2X TC, the 400mm f4 DO II delivered sharp images wide open. BUT you need to be very careful with vibration due to mirror slap and other vibrations. Using Live View mode and a remote cord, I could consistently obtain sharp images @ f8 using the 7D Mk II.
This lens is a keeper for me because it has longer reach than the 300mm and sharpness is very good - with or without TCs