Since more than one person is comparing it to the Nikon F 200-500, I will throw in my two cents (take it or leave it). My brother (who now uses Z9) had a 200-500 when he was F mount and was never happy with the image quality and got rid of it. A few months ago I ordered a 200-500 in an attempt to get back to one system, with the intent of selling my Sony 200-600 since all my other gear was Nikon F. As soon as I got it I did comparison shots at a few different equivalent focal lenghts and settings, all on a tripod with fast aperture. I even downsized the Nikon D850 files to the same pixel count as my Sony A74 to make it match. In every single instance, without exception, the Sony images were dramatically sharper (when enlarged to actual pixels). I sent it back and ordered a Nikon 80-400 and did the same tests and it was much sharper. It was not quite on par with the Sony, but much closer.
Though I was going to sell the Sony (and even had it listed here for about a month), I finally decided there are times I need 600mm and the lens is just too good to give up. So I flipped and sold all my Nikon F gear instead (to KEH and I expect the check to arrive today). Though I love Sony lenses I am not crazy about the body ergonomics (the aperture dial being on top instead of on back is a bad design IMO). So when the check arrives I am going to my local dealer to order Z8. I will continue to use two systems for now, though when Nikon eventually releases a 200-600 (sometime around the year 2035) I may switch to all Nikon Z. Mirrorless lenses are inherently sharper than SLR lenses, so I am sure the upcoming 200-600 will be fine even if it's non-S. I have a feeling the S designation may be as much for build and weather sealing as it is for sharpness. Since I don't shoot in severe conditions that is not a concern for me.
Though I was going to sell the Sony (and even had it listed here for about a month), I finally decided there are times I need 600mm and the lens is just too good to give up. So I flipped and sold all my Nikon F gear instead (to KEH and I expect the check to arrive today). Though I love Sony lenses I am not crazy about the body ergonomics (the aperture dial being on top instead of on back is a bad design IMO). So when the check arrives I am going to my local dealer to order Z8. I will continue to use two systems for now, though when Nikon eventually releases a 200-600 (sometime around the year 2035) I may switch to all Nikon Z. Mirrorless lenses are inherently sharper than SLR lenses, so I am sure the upcoming 200-600 will be fine even if it's non-S. I have a feeling the S designation may be as much for build and weather sealing as it is for sharpness. Since I don't shoot in severe conditions that is not a concern for me.