The Alpine Astronomical Baader 2" 90° Amici Erecting Diagonal is the ideal addition to your accessory kit for low-to-medium magnification celestial and terrestrial observations. The large 2" holder and nosepiece provide a spacious 38mm clear aperture that allows you to take full advantage of the large eyepiece's light path without vignetting. Its integrated erecting prism has seven-layer anti-reflection multi-coatings on the exterior surfaces to maximize light transmission, while highly reflective 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. The prism corrects the view horizontally and vertically so it can be used to observe earthbound subjects in refractors or Cassegrain-style telescopes. Alpine includes a holder reducer adapter that allows you to use the smaller and more common 1.25" size eyepieces, and to improve views the nosepiece is threaded to accept standard 2" eyepiece filters. Due to the optical limitations of the erecting prism system, the Amici is not recommended for high magnifications as you may experience color fringing and other aberrations.