Fast f/4 optics: With a bright f/4 focal ratio, the Quattro Imaging Newtonian captures greater detail in a shorter exposure time 2-inch dual-speed crayford-style focuser: Never miss focus with this 2-inch dual-speed crayford style focuser Oversized secondary mirror: All Quattro Newtonians use an oversized secondary mirror capable of illuminating both APS-C and full-frame DSLRs without vignetting Knife-edge baffles: Multiple knife-edge baffles minimize stray light from entering the optical tube and ruining your imaging or viewing experience Everything you need: While most manufacturers make you pay extra, Sky-Watcher gives you everything you need right out of the box, including: tube rings, a Vixen-style dovetail, and an 8x50 straight-through finderscope and bracket