I get a constant flood of questions about cameras. Many are pretty easy to answer, but sometimes an answer is not quite clear-cut and needs a fair amount of verbiage to answer well. The toughest question I'm getting these days, and with increasing regularity, is this one (and similar variations):
"Which body would give superior results if you are considering ONLY landscape photography and portrait photography: the D850 or Z9?"
First problem: there might be a difference in answer for landscape photography than there is for portrait photography. So let's tackle the two separately and see what happens.
Landscape: One of the reasons for the question is probably that 45mp count that both cameras feature. The suggestion on pixel count alone is that they might be the same. They're not, and in really subtle ways that I can't necessarily declare a winner on.
For instance, the D850 has about a one-third stop more dynamic range than the Z9 at base ISO, and that slowly increases to about two-thirds of a stop until you hit ISO 400. From ISO 500 onward, the cameras have near identical dynamic range. For most landscape work you use the lowest possible ISO to get the highest dynamic range, so the D850 has a small, but potentially visible advantage. That advantage is ever-so-slightly better than it first seems, as the phase detect pixel rows on the Z9 can have a small impact on deep-in-the-shadows detail.
Moreover, the D850's advantage comes mostly from input-referred read noise. That means that electronic noise handling is slightly better in the resulting DNs. Random photons tend to be fully random, but read noise can be dependent upon something (remember those focus pixel rows).
So the temptation would be to call landscape a win for the D850.
Not so fast, Bunky.
On long exposures the Z9 has far less tendency to hot pixel and seems to produce results that have less noise clustering than the D850. Like the D6, the Z9 seems to have very low fixed pattern noise, and produces excellent results on long exposures, including astrophotography.
So before you conclude about landscape use, you need to evaluate what type of landscape photos do you need the most integrity from.
Plus, there's this to consider: if you want to evaluate landscape focus via the viewfinder, well, the Z9 is clearly better, offering you both magnification and peaking.
So who won? ;~)
Portrait: Here the Z9 has the initial clear advantage in that it has a built-in vertical grip, and can perform face/eye detection across virtually the entire composition. I like the gridline choices on the Z9 better, too. I am surprised that Nikon left off Portrait Impression Balance off the Z9 after adding it to the Z6 II and Z7 II, though. That would have also chalked up as a clear win for the Z9.
However, one thing that keeps coming up is this: flash. It's not that the Z9 has fewer flash capabilities than the D850, it's that in any situation where you're relying on the flash or strobe to provide the exposure for a subject, the Z9 becomes a bit temperamental. As I've written many times, if you underexpose the focus sensor—as you often do in a studio strobe situation—your focus performance suffers. You can adjust that some via camera settings for the viewfinder and focus, but getting that nailed takes some time you might not have.
Other subtle flash/strobe bits come into play, as well, and those tend to all have to do with the timing of the all electronic shutter (Z9) versus the mechanical shutter (D850). Obviously, there's the top sync speed (1/200 versus 1/250), but there are other small bits you have to watch for, too, mostly dependent upon how you're triggering the flash/strobe. Early on I found the PocketWizard kit to be less reliable on the Z9, and PW's answer is more expensive. But I've seen other trigger issues with other third party accessories as they all try to figure out the exact timing of the Z9's electronic shutter.
And if the backgrounds of the portraits you're taking have LED lighting in the background, which is happening more and more often at fashion shows and will likely start to hit the red carpet someday soon, the electronic shutter of the Z9 would be potentially throwing up artifacts of mis-aligned LED/shutter timing (yes, I know the latest Z9 firmware has an option to help tune this, but you're going to spend time trying to find the right value).
So who won? ;~)
Final Notes: As I noted, this is a tough question to answer when it comes up. More often than not the camera comparison questions I get are much more clearcut, and I'll point out the camera I'd favor and why. However, as you can see here, subtleties that might come up via personal preference or specific situation can alter the analysis. And we haven't even gotten to a discussion of lenses ;~)
Would it matter to me? No. While the subtle differences are certainly there, I'm used to working around them when they come up. They always come up. It's more how fast you can recognize the change and figure out how you're going to deal with it that's important, not the camera. That's because no matter which camera you choose, something will come up.
My final answer would also tend to say this: if the money saved by buying the D850 would have you putting that into getting a better lens, get the D850.
