I went to Mt St Helens for a Milky Way workshop this past weekend. I was using my D700 with a Rokinon 24mm f/1.4 manual focus lens. I used Exposure Delay on my camera which effectively puts the mirror up and takes the shot after a one second delay while using only one shutter press.
Here's one of the images. I used an aperture of f/2, 15 seconds shutter speed and ISO of 1600 to get this shot.