The Testar 30mm Mini Guide Scope has a focal length of 120mm and a focal ratio of f/4. The objective is a fully multi-coated achromatic doublet for a greater optical precision. The mini dovetail bar can be firmly mounted on any standard finder scope bracket so you do not require any extra piggy back dovetail bar on your telescope. The base of the finder scope includes a 1/4" female thread for a wider compatibility among telescopes. The focus is achieved by rotating the objective lens that can be locked in position using the red ring. This scope is compatible with all guiding cameras. Testar 30mm F/4 Mini Guide Scope with QHY 5L-II camera - back focus from rear of front cell to focus ring approx. 16.4 mm. Testar 30mm F/4 Mini Guide Scope with ZWO ASI120MM camera - back focus from rear of front cell to focus ring approx. 13.2 mm. Testar 30mm F/4 Mini Guide Scope with ZWO ASI120MM Mini camera - back focus from rear of front cell to focus ring approx. 48.6 mm. Specifications Objective lens diameter 30 mm Focal length 120 mm Camera/eyepiece connection 1.25" and male M42 Weight 333 gr Max tube length 160 mm (focuser fully extended) Focus travel 0~47.5 mm Focuser type Rotative objective lens Dovetail specifications 31.8 mm x 35 mm - fits finder scope brackets Dovetail threads 1 x 1/4" Included items Guide scope 30mm Tube rings Objective lens cap Eyepiece cap Mini dovetail bar for finder scope brackets X 2 nylon tipped screws for locking the scope in the rings Thumb screw to secure the camera in the 1.25" barrel Allen key
