The 81mm BT81S-A Astronomical Binoculars - OTA from Vixen Optics are astronomical observation binoculars 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 upright-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.

This HF2 Altazimuth Fork Mount from Vixen is an altazimuth mount that's designed for use with large astronomical binoculars. The fork mount can be fixed to most sturdy tripods with a 3/8"-16 mounting-stud, including Vixen's HAL130-GP and HAL130-SX tripods. To complete the assembly, an appropriate swing bracket must be attached to the binocular.

The HAL 130SXG Aluminum Tripod from Vixen Optics is compatible with Vixen's Sphinx and GP telescope mounts. The adjustable height allows the user to set the position of the telescope to their liking for easy and comfortable viewing. The top of the tripod, where the mount attaches, is powder-coated for a durable finish that resists flaking and fading. The tripod is also collapsible for convenient storage and portability.