Planetary imagers are relatively inexpensive cameras that attach to your telescope like an eyepiece and work in concert with a PC via USB connection.
CCD cameras are the ultimate tool for astrophotography, providing a greater dynamic range and less noise than most DSLR cameras.
Autoguiders work in conjunction with a telescope mount to keep a celestial object from drifting during a photographic exposure.
Camera adapters are used to attach a CCD or DSLR camera directly to a telescope without using an eyepiece.
Camera mounts are used in applications where the camera will use its own lens to capture and focus the image.
Filter wheels are used in concert with monochromatic CCD cameras to achieve a composite color image.
Imaging filters include both simple RGB filters for creating color composites using monchrome cameras and highly specialized narrow band filters for capturing detail in emission nebulae.
Focal reducers are primarily used in astrophotography to compress the light cone
exiting the telescope down to a size closer to that of the sensor within your camera.
Extension tubes and spacer rings are often required to reach focus or to achieve the proper spacing between a focal reducer and the image plane.
Achieving a sharp focus is one of the more fundamental challenges faced by beginning astrohpotographer.