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Hi all! I'm an amateur wildlife photographer & I've been shooting a d500 for 5 years now, with a 200-500 & a 600 f4. Lately I've been attempting to get more environmental/loose compositions of my subjects, and I often feel that I'm beginning to push up against what a crop sensor can feasibly do. I'm planning on my next camera to be a full-frame sensor for that reason, and for the longest time I was decided on a used d850. Recently however I found out that the z8 has a specific feature that'd be a game-changer for me (Pre-release capture), but with the caveat of currently being above my price range and needing either new lenses or the FTZ adapter. I'm wondering if I should purchase the d850 to give me a full-frame option now (And a 2nd camera as insurance) or wait a little while to save up for the z8. Thanks in advance!
Hi Bird Guy. I'm also a bird/nature/landscape photographer, with an emphasis on small birds. I had a D810 and a D500 at one time. I liked full-frame for the better image quality when I could fill the frame (especially landscapes), as well as the wider field of view when shooting with long prime lenses like my 500 f/4 with TCs. However, I really appreciated certain features of the D500 like the moveable rear screen, better live view, faster AF, larger buffer and faster frame rate. So, I sold the D810 and got a D850, which combined the best features of the D500 and D810 cameras, albeit with a slight reduction in AF speed and buffer, and slower frame rate from the D500. To achieve 9 fps, I added a battery grip to the D850, which made it about the size of a D5. I liked the D850 enough to sell my D500 and get a second one, also gripped. I chose not to pursue the early Z6 and Z7 bodies (l and ll versions) as their AF was not fast enough. I never got a D5 due its smaller 21 MP sensor, size and high cost.
Then came the Z9 mirrorless flagship camera, and I jumped on it. It was actually a tad lighter and smaller than the gripped D850s, and appeared to be a mirrorless version of a mashup of the 45mp D850 and the fast-focusing D5 with many refinements for $1000 less than a new D5 or D6. However, battery life was reduced, and for my purposes, its AF was a mixed bag. It was better than the D850 in some ways and worse in others. Enough worse that I considered returning it. The problem was that if it lost focus, it would lock onto backgrounds and not budge without manual intervention or recomposing on a closer frame-filling subject. It was also less capable of focusing on BIF with busy backgrounds and couldn't find OOF birds nearly as well. I really missed the D850's group AF. The Z9 did offer subject identification, but it was rather hit or miss. I found myself having to manually assist focus much more than with the D850. This was two years ago. However, AF speed was excellent, especially with TCs, and it could autofocus much better with maximum apertures of f/8 or smaller (nice when using f/5.6 lenses with TCs). I've really appreciated the much quieter operation with no vibration, very OVF-like and brighter EVF which shows the effects of the exposure settings, and faster frame rates. The rear screen was more flexible and there were more custom controls on the body. Over the past two years, the Z9's AF has improved significantly. It still has a tendency to lock on backgrounds, but there are workarounds, especially with Z lenses; and subject identification, especially for birds, has been greatly improved. Pre-release capture, as you noted, has also been added. So the current Z9 is substantially better than when originally released. Bottom line, taking everything into account including some niggles with the AF, I found myself using the Z9 virtually all the time, and using the D850 only when I wanted a second camera with a different focal length lens.
So then came the Z8, which has taken most of the functionality of the current Z9 and compressed it into an ungripped D500/D850ish-sized body. Probably its biggest drawback compared to a D850 is its battery life, but Smallrig third party batteries are relatively inexpensive, and they can be charged either in camera or with a USB charging cord. A grip can also be added for extended battery life, but with no added performance changes. I was initially reluctant to add a Z8 based on fewer Fn buttons than the Z9, reduced battery life, only one CF express card slot, and the fact that a refurbished Z9 could be bought for about $500 more than the original retail price of a Z8. However, I recently purchased a refurbished Z8 for $3200 and I've found the transition almost seamless. I really appreciate the reduced weight (compared to the Z9 or gripped D850), especially when shooting handheld with long lenses. I now shoot primarily with the Z8 and just change batteries more often.
I've gone through this long-winded reply in hopes it might help you with your decision. You're on a similar path as mine but with the option to jump several years forward with the Z8, or move along more incrementally with a D850. There's no right or wrong answer. For my shooting, I found the D850 a step up from the D500 for the same reasons you mentioned, but keeping in mind that a grip was needed to achieve 9 fps frame rate versus 7 fps for the ungripped body. So from that standpoint, purchasing a used D850 would be a budget friendly upgrade with no AF learning curve. Hopefully you could afford to keep the D500 as a backup, if desired. IQ of the images will be just as good as what's produced by the Z8. If you could wait a couple years, a D850 might be worth keeping until the next iterations of the Z9 and Z8 come out or prices fall on the Z8.
It really boils down to your budget and your need/desire to jump ahead to a Z8 versus meeting your immediate needs with a D850. The Z8 is more fun to shoot, offers much faster frame rates without the need for a grip, and creates some shooting opportunities not offered by the D850; but the D850 is still capable of producing outstanding images.
