Photography is all about capturing light, and dedicated astrophotography equipment is designed specifically to let as much light in as it possibly can. The cameras need to have good noise handling, the lenses need to have a wide focal length and big aperture, and you may even want to invest in a star tracker to help counteract the movement of the Earth in long-exposure astrophotography. While you can get away with basic astrophotography with most photography gear, dedicated astrophotographers will want to invest in gear that will produce the best results.