ePhotozine has reviewed the Nikon AF-S NIKKOR 180-400mm f/4E TC1.4 FL ED. Although they give it a rave review for IQ, it is obvious that there is a dramatic drop in MTF on going from 300-400mm
https://www.ephotozine.com/article/nikon-af-s-nikkor-180-400mm-f-4e-tc1-4-fl-ed-review-32085
and the resolution on an 850 is poorer at 400mm than is that of the Tamron 100-400mm in the centre on a 5DSR.
https://www.ephotozine.com/article/tamron-100-400mm-f-4-5-6-3-di-vc-usd-lens-review-31750
No doubt it has advantages of f-stop and AF, but not the IQ you would expect from such a pricey beast.
https://www.ephotozine.com/article/nikon-af-s-nikkor-180-400mm-f-4e-tc1-4-fl-ed-review-32085
and the resolution on an 850 is poorer at 400mm than is that of the Tamron 100-400mm in the centre on a 5DSR.
https://www.ephotozine.com/article/tamron-100-400mm-f-4-5-6-3-di-vc-usd-lens-review-31750
No doubt it has advantages of f-stop and AF, but not the IQ you would expect from such a pricey beast.
