The Alpine Astronomical Baader 2" 90° Deluxe Astro Amici Erecting Diagonal is an ideal addition to your observing kit when used in larger drawtubes and visual backs on refractor and Cassegrain-style optical tubes.
The heart of the diagonal is the Amici prism system. Made of BK7 glass, the roof prism corrects views horizontally and vertically to make it ideal for both astronomy or terrestrial use. Anti-reflection Phantom Group multi-coatings on the exterior prism surfaces maximize light transmission across the entire visible spectrum, while highly reflective Broad Band Hard Silver (BBHS) coatings on the interior prism surfaces virtually eliminate diffraction–resulting in very little light loss through the prism system and ensuring views remain bright and clear. A spacious 44mm clear aperture helps to prevent vignetting when imaging with larger sensor cameras or when using low-to-medium magnification eyepieces. The 90° angle of the diagonal places your head in a comfortable viewing position when the telescope is aimed high overhead or directly forward.
For the eyepieces, the proprietary 2" ClickLock holder is used. This unique eyepiece mounting system is superior to conventional compression-ring and set-screw holders. The ClickLock system uses three long roller bearings to hold the eyepiece firmly centered in place without marking or marring it, while eliminating wobble and off-axis tilt. A simple 20° twist locks and unlocks the clamping system for fast eyepiece changes even while wearing gloves. The 2" nosepiece has a series of shallow safety kerfs (grooves) cut into it to firmly lock it in place and resist the tilt that is common if the focuser's clamping system isn't quite centered. The nosepiece is threaded on both the front and rear to accept standard 2" eyepiece filters. Install a filter on the front to make changing it easier, or on the back (inside the housing close to the mirror) so as to not add any optical distance.