I got the D850 on Friday and tested it in figure skating photography using 300/4 PF, 70-200 FL and 200/2 II. I am left with mixed feelings.
The good: images are stunningly detailed. The touchscreen functionality is much more general than in the D5 and works well. Tolerably good images in artificial light at ISO 6400 (with the D810 I was happy until ISO 2000). (Unrelated to figure skating photography: When tested with a stationary subject, he 300 PF hand held in quiet mode give visibly sharper images at 1/50s (with EFCS on) than in S mode: it seems the slower rise of the mirror and the electronic first curtain now are available for hand held shooting and work brilliantly in Q/Qc modes. )
The surprise: Snapbridge worked basically as one would expect if one hadn’t read all the bad reports of v. 1.0. I was able to connect to my iPhone 6 without problems and automatic transfer of small jpgs worked fine as long as the camera was set to record both raw and jpg. I didn’t try full size image transfer. Also the camera remote control with exposure adjustments worked as well as sending manually selected images. Stopping automatic transfer didn’t work immediately - it took hours to clear the buffer of images in the queue it seems and I would appreciate a refinement where automatic transfer is suspended immediately so I can speed up the transfer of priority images selected manually.
The not so good: Well, sometimes the camera would hesitate to focus on the skater. When I lost my patience I lifted my thumb from AF-ON and pressed it again then it would focus. The shots that the camera would take were generally in focus and highly detailed. However, the hesitations happened every once in a while. Sometimes the camera would not respond to controls in image review (playback). It would take some time before it got ”online” again. I was mostly using D25 and group-area AF. I think the AF hesitation mostly was in dynamic area mode.
I have some theories/speculation. I suspect either the camera is busy processing the rather large files and this causes bottlenecks / delays in AF processing, or there may be a firmware bug. Switching back and forth between the two cameras left the impression that one was much more responsive than the other.
I am a little disappointed. I understand that a 45MP camera isn’t likely to be as fast as a 20MP one especially when the latter is purpose-made for action and more expensive. However I expected the responsivity to be closer. I have no complaints about AF accuracy - after auto fine tuning all my lenses seemed to focus where they needed to (with excellent detail). It’s just that I am used to immediate response when I request the camera to do something and this behaviour was unexpected.
I’ll talk to Nikon about this when I get the opportunity and when I have more experience with the camera.