Astrophotography is basically taking pictures of night sky using a DSLR attached to a longest telephoto lens; which in most cases is a telescope. Due to hyper-large distances to the subjects, using any other lens would result in just a black photo of night sky with a white dot representing the Moon on it. So, in order to get decent results you would need to use this very specific set of gear.
However, if you decide to try yourself in this area of photography, don’t get scared away by the gear prices. If you do some research you’ll see that a telescope actually costs less than most top-range DSLR lenses.
Astrophotography is often an extension of what some astronomers do. Many decide that it would be great to share with the world what they see in the night sky. And they are absolutely right! Images of stars in the night sky are just amazing!
As mentioned before, you would need the right gear to get these awesome images. Apart from your camera, essential pieces are: a T-mount (to attach your camera to the telescope) and remote or cable shutter release (to avoid any camera shake). Important thing to keep in mind: if you have in-camera image stabilizer – turn it OFF. Otherwise it will try to “stabilize” the camera that is already stable on a tripod and will result in minor image blur. Rule of thumb is – never use image stabilizer if using a tripod.
If you are unsure if you wish to pursue this hobby or not, you can give it a simple try. Get the longest lens you have and set your camera on a tripod when there is a full Moon. Zoom in all the way and snap a few shots. Then get those “white dot” photos imported into Lightroom or Photoshop. Magnify them till the Moon is about 10cm in size on your screen and crank the whites down, so you can see a bit of a detail. You will feel right away if it “clicks” within you, if you will catch yourself striving to have a better image of this to see more details.
If you decide to try astrophotography, you’ll find soon enough that the gear is the least issue in this area. Hunting the stars is where you will spend most of the time. Despite they look like not moving, once you start focusing they will appear running away all the time. It takes time, effort and a bit of luck to get an outstanding photo of space and stars, but the results are well worth it.