Here you can see the Canon 40D DSLR camera's attachments that are used when imaging with the Vixen ED80Sf telescope.
On the right is the DSLR camera body, which is stock except that it's had its IR filter removed. It is controlled via the USB interface and a software program called Nebulosity
Next is the T-Ring adapter that attaches to the DSLR body in the same way a lens would.
The T-Ring screws onto the next item, which is a Williams Optics Focal Reducer/Field Flattener. This optical device reduces the focal length of the system by 0.8x and fixes coma. Coma
is the "stretching" of stars in the corners of images. Look closely at astronomy photographs and you may notice that the stars in the corners are not pinpoints of light, rather they are short lines. The field flattener attempts to minimize this effect.
Finally, on the left is a light pollution
filter. This filter blocks certain wavelengths of light that are from known sources such as sodium and mercury-vapor streetlights.