Astro-Tech 8” f4.0 Imaging Newtonian
The AT8IN is modified specifically for astrophotography by astronomics:

This 8” Astro-Tech AT8IN optical tube is a very fast focal ratio f/4 reflector that has been optimized for wide field deep space imaging.

(above from the astronomics web site).
Dual Speed Crayford Style Focuser ¦ Coma Corrector and Field Flattner