The 81mm BT81S-A Astronomical Binocular - OTA from Vixen Optics is an astronomical observation binocular allowing interchangeable eyepieces that provides exceptional terrestrial or celestial observing. The twin 480mm f/5.9 achromatic refractors have permanently attached 45° diagonals. They accept the entire lineup of Vixen NPL Plossl eyepieces and have an enormous 56-101mm interpupillary adjustment range to work with nearly any set of eyes, including many children's.
For remarkable depth perception and contrast, there is nothing that beats the ease and comfort of erect image binocular viewing. Expect high quality observing of terrestrial vistas and celestial views alike which is easily transported to your favorite dark sky location out and beyond. Take a drive to nowhere on a clear, new moon lit night and be awe struck! The Pleiades and the Moon's terminator never looked like this.
This permutation of the BT81S-A arrives with the binocular optical tube assembly (OTA) only. Eyepieces, mount and a tripod or base need to be supplied by the user.
Accepts multiple 1.25" eyepieces
Visual back 31.7 mm - friction fit
Built-in carry handle and finder bracket
Mount block dovetail bar for SX/GP tripods
Interpupillary distance adjustment range of 2.2-4.0"
Resolving power of 1.43 arc seconds and light gathering value of 134x