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
Gemini Downloads page
Featuring identical OPTEC-4300 mechanical interfaces front and back, the Gemini can be easily fitted to most any large telescope OTA.  Recessed oval point setscrews provide three-point direct contact with the heavy wall OPTEC-4300 dovetail mount.  Gemini’s clear aperture of 3.75″ is maintained through each adapter, passing even large light cones through to the camera image plane without vignetting.
On the camera side, the Gemini package now includes our #19830 OPTEC-4300 to DSI threaded adapter.  This part converts the camera side to a receiver for any of our Optec-DSI 3.5 High Performance spacers configurable to 1/4″ increments when additional back-focus spacing is needed. 
Currently designed telescope adapters include support for the AG Optical iDK’s, Celestron, Ceravolo Optical Systems Astrographs, Meade 16-inch class SCT, Plane Wave Secure-Fit, and Takahashi telescopes.   
Additional adapters available through PreciseParts.
Package Contents

#19750 Gemini 96 Focusing Rotator

Gemini Controller
#19752 Gemini Hand Controller
Optec USB/Serial communications cable, 6-ft. length
2X CAT-5e/CAT-6 Ethernet cable, 6-ft. length
12VDC 1.25A power supply – 110-240VAC input
UL/CSA compliant wall plug cord
#19830 OPTEC-4300 to DSI
Pelican type case


Gemini 802.11bg WiFi
19691 Mounting Bracket
17680 In-Out Keypad

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