IDguy wrote:
I am sure it will measure up to the 200-500 in image quality.
My decision on that will be determined by price. As noted above, Tamron and Sigma lens prices tend to be about 1/3 of Nikon. I suspect they will be coming out with Z mounts in the near future. Once they do it should be easy for them to proliferate across their offerings. Perhaps Nikon will recognize their competition. They seem to have done so on the 200-500, but so far not on many of the Z lenses.
And 1/3 the quality of a Nikon lens. IMHO