Should every thread be a physics lecture? If so, then this forum would die quickly.

Some recommended software to try. Some shared their experiences with cameras they own. The OP did not initially mention already owning a D850. I suggested if one looks in that direction, a newer camera might be a better choice. Then you throw in a joke or two. This is how people interact with each other on this site. It makes the site more interesting. Some threads do deteriorate into stupidity. You have to take the bad with the good, and there is a lot of good here.

The D850 is a fine 2017 camera. The IQ is unsurpassed, essentially the same as their newer 45 megapixel mirrorless cameras, of which you can chose from three, Z7 ii, Z8 and Z9. The Z cameras run circles around the D850 in terms of speed and features, so why spend money on the old camera? Why not move into the present if you're going to buy a new camera?

The only advantage I see in the older camera is that it will autofocus with the very old screw drive lenses, some of which are actually decent. If you don't own or plan to use any of those, there is no advantage except perhaps price. If you find that you have to buy some full frame lenses to go along with a full frame camera, then the Z lenses are the best that Nikon has to offer, and you really need the best you can afford with a camera that has a high pixel count. Think about how far you would want to take this.