The 70-200mm f/2.8 VR II when coupled with the TC-20E III is both limited in terms of sharpness and that is again limited by the distance to the subject.
Meaning, if the subject is more than 15 meters away, the sharpness tend to drop significanty. Even when it is lesser than 15 meters, according to reviews, the drop in sharpness percentage is 26%. Not to mention the need to drop the aperture to F8 to achieve maximum sharpness.
One also has to AF fine tune when both lens are coupled together.
Having owned and use this combination, i have to say that it really depends on the level of compromise one is willing take in terms of sharpness. For me, it is sharp enough for most applications but not for photographing birds when you want to see the details of the feathers or for viewing at 1:1
I have discussed coupling the 80-400 VR with the TC-14E II with an old friend of mine who is a renown Nikon photographer and we believe it should be a workable combination as the TC-14E II is known to only degrade sharpness by 5% and with bodies like the D600/800/D4 that can all AF at F8, it should be a workable combination.
Doing the maths:
70-200mm f/2.8 VR II + TC-20E III costs around 3,700 to 3,800 and gives 140-400mm f/5.6 thats needs to be stopped down to F8 for maximum sharpness
80-400mm VR + TC-14E II costs around 4,010 to 4,050 and gives 112-560mm f/8 that "IN THEORY**" should be able to be used wide open. (** Based on experience of the TC-14E II, it can be used wide open on all Nikon super telephoto lens like the 300mm f/4, 70-200mm f/2.8 VRII and other exotic super telephoto lens)
For me, i wont be getting the 80-400mm VR because i already have the 70-200mm f/2.8 VR II, 300mm f/2.8 VR II and the TC-20E III. I'll just mix and match and live with the compromise that i have accepted.
Output similar ? If any chance of using, let us know the result.
