There are cameras that work best during day time but are horrible for filming the sky at night-time. A camera is not the only equipment needed to capture night sky images. You also need to invest in good lenses and tripods. A steady tripod is needed during long exposure time which is very common for night sky videography. A poorly built tripod can be shaky causing blurred images. Experienced videographers highly recommend Really Right Stuff tripods, ball heads, and L-brackets to use at night.
As for the camera, it is advisable that you choose a model with Manual Mode Functionality. This will let you manually adjust the Aperture, Exposure time and ISO by hand. For specific models, the following types of cameras and lenses can help you film the Milky Way better.
Full Frame/ 35 mm Camera. This lets you film a lager “surface” of the Milky Way. It also lessens the amount of noise in high ISO video, in turn providing good quality of RAW files.
The Nikon D810, together with Nikkor 14-24mm lens, has a tough body and considered to be the best full frame night video camera.
For wide angle lens, a f/2.8 minimum aperture works best. The smaller the “f” size, the wider the lens can open. A wider opening means that the lens will allow your camera’s sensor to capture as much light as possible in a short span of time. A great sample of a wide angle lens is the Nikkor 17-35mm f/2.8 D ED-IF Autofocus Lens.
Wide angle lenses between 10mm to 17mm work best for full frame cameras. The same can also work for crop sensor cameras but with apertures between f/2.8-f/4 are recommended.
You can use Nikon D800 as your back up camera. D810 is better because it has more dynamic range but it won’t hurt if you will bring another camera especially if you are going to do long distance trips.
Now that you know the types of equipment you need, the next thing you need to understand is how to track where the stars are and what is the best time and date to witness them. At this age, it is easier to know when and where the stars are going to reveal themselves. There is an online app called Stellarium which is like the Google Earth for stars. All you have to do is to enter certain information like the location for your shooting and what time you’re going to be there. It will show you the moon phase, the brightness of the sky, and the star fields that will be visible in your naked eyes.