Rotator Focuser - Gemini Focusing Rotator
Gemini Focusing Rotator
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Gemini Focusing Rotator



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Optec engineers have developed a completely new concept for combining telescope focus and camera rotation functions into a single robust, yet compact package. Rather than simply adding a rotator onto the end of a focuser drawtube, Gemini was designed from inception with a rotating drawtube providing superior strength and rigidity for heavy camera payloads. Featuring four lead-screws and four linear bearings, Gemini can easily handle 10-kg. (22-lbs.) payload packages without flexure. Full 360-degree rotation is a built-in function of the Gemini with a full 1/2″ of linear travel. At the center of travel, Gemini measures a mere 2.45″ in thickness.

Like all Optec focuser products, Gemini includes a remote temperature probe for automatic temperature compensation.  Simply attach the temperature probe anywhere in the linear response zone of your OTA (usually the tube or truss assembly) and Gemini will automatically keep the camera package in sharp focus. The Gemini Commander software provides a convenient wizard to help determine your telescope’s TC or temperature coefficient.

To maintain a flat, rigid base for heavy camera packages, Gemini’s shell consists of two parallel plates machined from MIC-6 tool plate providing flatness within 0.001″ (25 microns).  Seven precise stand-off spacers maintain the 2.2″ separation of these plates.  The rotating drawtube is moved linearly with 1/2″ of total travel using a premium timing belt driven by a high torque stepper motor.  The entire package is accented with a beautiful carbon fiber wrap.  Dual RJ45 connectors provide connection to the Gemini Control hub.  The independent rotating drawtube is supported by a custom X-cage bearing system supported by large, 6mm chrome ball bearings. 


Specifications for Gemini and Controller:

Focusing Rotator Physical Specifications:
  • Clear Aperture: 3.75″ (95mm)
  • Back-Focus Usage: 2.2″ to 2.7″ (55.9 to 68.6mm)
  • Focuser Travel: 0.5″ (12.7mm)
  • Focuser Resolution: 0.11 microns per step
  • Rotator Resolution: 600 steps per degree
  • Minimum Overall Thickness: 2.2″ (55.9mm) [Full IN position]
  • Dimensions: 9.4″ x 7.4″ (239mm x 187mm)
  • Weight: 6 lb. 6 oz. (2.9 kg)

Gemini Controller Hub Specifications:

Controller Hub Specifications:
  • Length: 5.1″ (130mm)
  • Width: 3.2″ (81mm)
  • Height: 1.0″ (27mm)
  • Weight: 10 oz. (285 g)
  • Mounting Holes: Four 4-40 x 1/8″ depth (reverse side)
  • Case Material: 6061 aluminum, anodized black.
Gemini Hub Port Connections:
  • Focuser: RJ45 socket for standard Cat-5e/Cat-6 cable to Focuser port
  • Rotator: RJ45 socket for standard Cat-5e/Cat-6 cable to Rotator port
  • Power: 12VDC input, 2.5 x 5.5mm plug, center pin positive
  • Network: Standard RJ45 Ethernet socket
  • Hand Controller: RJ22 socket for standard telephone handset cord
  • Serial: RJ12 socket for Optec USB/Serial cable
  • Wireless: 802.11 WiFi option


 Gemini Documentation

Gemini Commander Quick Start Guide.

Gemini Hand Controller Quick Start Guide.

Gemini Dimensions

Gemini 3d PDF

Additional information

Weight 10 lbs


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