I’m DSLR on tripod only these days
, essential flip out screen, though most cameras seem to have a way to connect an external screen which might be a good option, but more cost and gear to set up and take down. I also think afocus highlight feature is handy too as you can get pin sharp on screen but you need to double check after taking a shot and rember to check middle and corners of shot too for shrpness, if the optical train is long and heavy there coule be flex throwing things off slightly corner to corner. A plug in cabled remote is good too, saves getting out to a site to find your dinky ir remote was pressed against something in your bag and battery dead flat. For myself I ditched camera batteries a long time ago. I use a usb to battery adapter, its a fake battery that goes into the camera body with a usb cable i plug into a larger capacity usb powerbank. So I have several times the capacity of two fully charged batteries, I used to use a battery grip but that let me down when i stopped workong once one battery was flat. Not a good buy on my part.
Also quality. Storage. Every camera I own has a large capacity highspeed Sandisk card (fastest rating ), you want to avoid possible bottleneck of the cameras write speed and its internal caching I’ve never had a single bad sandisk card over the years but i buy retail price from reliable authorised seller and I also run the card through capacity checks to ensure its a legit one not a fake. My D800e stores over 500 RAW+JPG during my sessions all perfectly fine files zero corruption and stores fast(I’m typically only shooting 1 sec exposures, just lots of them and I use a continuous shooting mode so it can just click over shooting until the card is full, no waiting for camera buffer to empty.
Also as you look at cameras carefully look at the noise you may feel you NEED the 60sec not 30sec limit but you might find the hotpixels and other noise are far too much so try to test in person and take home a couple of 60secDarks and the in camera high iso removal and long exposure noise removal may leave artifacts not good for astro but fine enough for general photography, I’ve seen camera leave blocky compression style artifacts behind with the noise reduction tools and disabling any or all can leave other things like edge glow or vastly pushed noise. Best you get some test shots instore of darks and bias too to take home to compare your existing camera, the on paper specs mean nothing its what the camera produces that matters.Astrophotography is a niche market segment manufacturer dont really cater to (except sometimes Canon)Any camera store should let you pop in a card of your own and take some test shots and you dont need any lens except what they use in store to take some bias and dark shots and try their noise removal options and push the iso etc. our AP needs are about pushing the camera to its limits so in store the camera is warmer than normal unless well aircondioned store I guess. So the different noise types should be obvious and the removal feature s easy to see effectiveness on camera but you need to test your camera and take the shots home to compare via pixel peeping with yours. Maybe even measure values in some package. What setting you use for actual shooting is irrelevant push the camera to their limit and note the lmit of your camera for exposure time and ISO setting and also use those settings on the camera you test as well as upping the values of the new cameras to their limit. That should give you a reasonable like for like comparison at “identical” settings(they aren’t of course, but the new cameras should look cleaner but maybe not by much and if at extreme limits should give you an idea of wether the new camera will give you cleaner subs or not at all, it may only be slight and in the extreme setting end you get much more noise and problems at each step available but only direct comparison of files against files will giv you an idea of the truth you’ll experience, ignore the sales talk and we’ve seen in the past the misrepresentation of sony sensors in nikons. You cant know for certain thecamera isnt doing harmful processing in camera that reduces your overal imaging potentional.
Hope you find the right camera and a helpful camera store. If you know the camera you want to test check what cards they use and try to take a few with you so they can format in camera if they dont trust you’re trying to infect their cameras, maybe you’ll have to buy a small card in store depending on store and staff helpfullness.