As far as I can determine with some playing around with the D800, the built-in intervalometer can shoot with bracketing, but not mirror-up. External controls, like Camranger, may have similar limitations due to the camera's control logic, but I still need to fully investigate that possibility. I most need a better/faster operating/more recent small Fuji APSC camera, so that's my thinking at the moment.
With some invaluable help from the internet I managed to get my D7200, D750, and D810 to all do (1) complete bracketing, (2) with the mirror up, and (3) with just one push of the shutter release on a wired remote. Settings:
1. Exposure delay mode ON (menu) (delay set at 2 seconds by personal preference)
2. Exposure mode set to self-timer* (delay set to 2 seconds by personal preference)
3. Bracketing set as desired (I'm doing nine at 1-stop intervals; there are some limits on what you can do here on different models)
4. Live view on
*Trying to use the remote mirror-up or time-delay remote settings doesn't work right, since each push of the remote button only releases one of the bracketed shots. I also tried "S" with exposure delay and that again caused only one bracketed shot to be released per button push. Ours is not to wonder why; Nikon's choices mystify.
I have bracketing set to under-MTR-over, in aperture-priority mode. With this setting, prior to the start of the bracketing sequences the exposure shown on the top LCD is the farthest under. Note that particular shutter speed in case there is any problem with possibly getting a partial bracketing set, losing track of where you are, and needing to know whether or not you need to get back to the correct starting point.
With these settings, one button push on the appropriate remote gets me nine bracketed shots with the mirror up. I also will have the D810 in EFCS mode to further reduce vibration. I've practiced the eclipse sequence with the main cameras and can get all of them to start and complete their sequences with minimal distracted time for myself.
Important viewing advice from a total solar eclipse veteran I listened to: If you look at the partial eclipse shortly before totality, including the diamond ring and/or Bailey's beads, you'll ruin your (partially adapted) night vision. He did this once and had an afterimage of the crescent sun superimposed on his view of the corona throughout totality.
Alternate approach: keep your eyes, or at least one eye, in the dark as much as possible before totality. This includes camera screens and monitors; mine will be turned maximally down or off after ensuring all settings including focus are correct (focus will be locked in by tape to avoid last-minute accidents). As totality prepares to end, view the transition to the partial eclipse as you wish, since you will no longer need to preserve your night vision. Just be aware that it's all to easy to watch Bailey's beads and keep on watching them transition to a crescent without discomfort, and thereby nuke your eyes in the process. The moment the sun peeks out, on go the eclipse glasses.
Corallary: I'm not going to try to capture any images of the partial eclipse prior to totality, not even Bailey's beads or the diamond ring. Your preferences may vary, but for me totality is the big deal and the first priority. I want to see the maximum coronal extent and detail with my eyes and I want to photograph it. I don't want to be changing camera settings or removing a solar filter at the last moment, thereby causing distraction, possible critical errors, and missing transient phenomena with my eyes. (Scopes and lenses will be covered until 15 seconds before totality to protect equipment. Optical viewfinders will be blocked with tape for safety.)
As totality ends I'll trigger another sequence with the camera on the larger scope, to try to capture Bailey's beads. Then on goes the solar filter, the settings are adjusted, more shots happen, and I cover up the other scope and lenses since their work is done.
I'll also be running other cameras on intervalometers and video, taking wide-angle environmental shots. A few minutes after totality ends, those will get turned off and turned away from the sun. I had no problem photographing a partial eclipse with a wide-angle lens in 2012.
I'm setting two timers (regular and backup) to go off 20 seconds before totality ends, as a warning. This is especially important if you're looking through binoculars or other optical instruments.
TEN-SECOND RULE. Wise advice I heard from that same person : If you run into photographic problems of any sort during totality and spend any more than 10 seconds trying to fix them, forget the camera(s) and just look at the eclipse. If you futz around trying to fix things, you're in grave danger of losing track of time and not seeing the eclipse with your eyes at all, let alone getting a good look at it. You don't want your eclipse experience to consist of frantic efforts fighting equipment or settings problems, followed by trying to see what you missed by looking at photos that won't be as good as the original in the sky.
You also want to take a few moments here and there before and during totality to look around at the sky and the weird lighting on your surroundings. I've seen up to 94% blockage of the sun and at that point it's like no lighting I've ever seen anywhere. It's certainly not anything like a sunset or sunrise.
