User manual
Vixen Optics BT81S-A 81mm f 5.9

User Manual for Vixen Optics BT81S-A 81mm f 5.9 Binocular Telescope with Pro Accessory Package

• Product category: Binoculars Vixen Optics
• Brand: Vixen Optics
• Description and content of package
• Technical information and basic settings
• Frequently asked questions – FAQ
• Troubleshooting (does not switch on, does not respond, error message, what do I do if...)
• Authorized service for Vixen Optics Binoculars

Product description

• 81mm BT81S-A Astronomical Binocular - OTA 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
  • Twin 480mm f/5.9 achromatic refractor telescopes with 45° incorporated erect image diagonals
• SSW 14mm 83° Ultra Wide Eyepiece (1.25") This 14mm version of Vixen Optic's SSW 83&Deg; Ultra Wide Eyepiece delivers an immersive observational experience through a combination of optics and coatings that work together to produce bright and clear images across the entire expansive field of view. Its performance starts with a seven-element lens design using high-transmission/low dispersion lanthanum and exotic glass which limits distortion (spherical aberration) and color fringing (chromatic aberration) for edge to edge sharpness with true color rendition. Complementing the glass are proprietary anti-reflection optical coatings which increase contrast and help transmit the light through the system with very little loss.Designed with a 1.25" barrel for use with the most popular focusers and accessories, each eyepiece in the series has its own unique color for easy identification at a glance. The color is an anodized finish on the aluminum body so it not only acts as an identifier;it protects the exterior as well. Rounding out the features is a 13mm eye relief, a retractable eyecup, and an hexagonal anti-roll design. The SSW series of eyepieces are made by Vixen in Japan.
  Optical Performance
  • • 14mm focal length
    • 83° ultra-wide field of view
    • High-transmission/low dispersion lanthanum and exotic glass
    • Anti-reflection fully multicoated optics for high-contrast images
  Use and Handling
  • • Sleeve design for use with compression ring and screw eyepiece adapters
    • Retractable eyecup with rubber grip for great viewing and comfortable handling
    • Eye Relief: 13mm
  Construction Details
  • • 1.25" diameter barrel
    • Lightweight aluminum body
    • Scratch and corrosion-resistant anodized finish
    • Color coded: Unique anodized color for each size eyepiece in the series
    • Hexagonal anti-roll design
    • Made in Japan
• XY Dot Finder Vixen Optics designed their XY Dot Finder as a faster alternative to conventional magnified finderscopes. This unmagnified optic puts a red dot in the center of the sighting window that, when properly aligned with your optical tube, allows you to simply cover your target object with it and have it centered in your OTA's eyepiece. This design allows you to see the entire night sky above you for faster scanning and movement versus conventional finderscopes that limit your field of view. With eleven settings, controlled by an easy to use rheostat dial, the dot intensity can be set at the most comfortable brightness so you can see the dot without affecting your night-adjusted vision. This dot finder comes with an aluminum mounting bracket that is compatible with all Vixen OTAs and one CR2032 battery.
• HF2 Altazimuth Fork Mount 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.
• HAL 130SXG Aluminum Tripod 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.
• Triangle Accessory Tray This Metal Tripod Tray holds your observing accessories and lock the tripod legs into place.  It fits Vixen and other branded tripods (bolt holes are spaced about 9.5"/241mm apart), including current aluminum tripods for the GP, SP, GP-DX, Sphinx, Porta & Custom-D mounts.

• Mount Block

• Limited Lifetime Warranty (Transferable)

• Limited 5-Year Warranty

• 50mm Finder Bracket (Tall)

• Allen Wrench

• CR2032 Battery

• Limited 5-Year Warranty

• Limited 1 Year Warranty

• Limited 5-Year Warranty

• Limited 1-Year Warranty

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Technical parameters

• 81mm BT81S-A Astronomical Binocular - OTA

  Objective Lens Diameter	81 mm
  Interpupillary Adjustment	8.7 to 15.7 mm / 0.3 to .6"
  Dioptric Correction	None
  Focus Type	Individual
  Tripod Mount	None
  Dimensions	18.9 x 7.4 x 6.0" / 48.0 x 18.8 x 15.2 cm
  Weight	9.0 lb / 4.1 kg optical assembly only

• SSW 14mm 83° Ultra Wide Eyepiece (1.25")

  Focal Length	14 mm
  Barrel Diameter	1.25"
  Eye Relief	13 mm
  Apparent Field of View	83°
  Dimensions	Not specified by manufacturer
  Weight	Not specified by manufacturer

  Box Dimensions (LxWxH)	4.7 x 2.4 x 2.2"

• XY Dot Finder

  Magnification	1x
  Battery	1 x CR2032
  Dimensions	4.5 x 4.5 x 1.5" / 11.4 x 11.4 x 3.8 cm
  Weight	9.0 oz / 255.2 g, with battery

  Box Dimensions (LxWxH)	6.0 x 6.0 x 1.0"

• HF2 Altazimuth Fork Mount

  Box Dimensions (LxWxH)	15.95 x 15.4 x 5.85"

• HAL 130SXG Aluminum Tripod

  Height Adjustment Range	25 to 39" (64 to 99 cm)
  Maximum Leg Spread	63.5" (161 cm) Diameter
  Construction	Aluminum 2-piece adjustable legs
  Folded Length	32" (81 cm)
  Payload Capacity	77 lb (35 kg)
  Weight	12.1 lb (5.5 kg)

• Triangle Accessory Tray

  Box Dimensions (LxWxH)	12.598 x 9.449 x 1.732"

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