Hi All;
Just wanted to share my experience with the Nikon Z7. I bought the kit with the 24-70 lens and the lens adapter so I can use older nikkor lenses. The Z7 is an amazing camera, Nikon did their research quite well. I had a Sony a7 some time back and sold it because it seemed too much like managing a phone camera, the images were great nut I didn't care for the menu system. The Nikon Z7 was laid out extremely well, I especially liked the "i" menu with quick access to the most common things I usually tweak.
However, I found one flaw that I just cannot get past, and I suspect it's a mirrorless issue, not just a Nikon issue - night photography.
Now to be fair, focusing issues with night photography are nothing new, in fact there are many tutorials online about setting your lens to true infinity focus for this very reason. The real problem is not the focus (although the same issue does apply) but when shooting in very low light situations what you see in the viewfinder, or in live view is nothing more than dark static.
I recently took a trip to Alaska to shoot the northern lights, found a great location, scouted the site early and went back after midnight. Unfortunately I was left with no way to compose my shots, or even see what was in the frame. The lighting was low but not black, in fact I could see quite well what I wanted to shoot, without the camera. See the attached shot of one of the images where I got lucky, I am somewhat shocked that the camera could not show me an image in the viewfinder, or in live view mode of this.
The next day I found a great camera store in Fairbanks (Alaska Camera) and bought a D850. That night I returned to the same location as before. Both cameras refused to autofocus, somewhat as expected, however I had no issues at all viewing and composing the images in the virefinder. So, as much as I loved the Z7, I've sold it and I love the D850 even more.