version does not directly support autoguiders with TTL output, but the newer version 

does. 

Gemini contains a separate Autoguider port   a 6 pin modular RJ 11 socket located 

below the 15 pin connector to the left.  The electrical connection is compatible with the 

Hand Controller port, but the signal used to drive the LED in the Hand Controller port is 

used for shutter control in the autoguider port.  The common pin of the RJ 11 modular 

connector is connected to +5V on the older version of Gemini, and GND on the newer 

version.  The 4 directional inputs must be connected to the common pin to be active (they 

are active at High potentials on the older version of Gemini, and at Low potentials on the 

newer version). Simultaneously activating opposing directional signals (DEC+ and DEC  

or RA+ and RA ) will be ignored and displayed as   Autoguider Error.     

Note:

 The autoguider port is only active in the Photographic Mode and All 

Speeds Mode of the Gemini system.  Selecting the Visual Mode disables Guiding 

and therefore the Autoguider Port.  

4.2.2  Manual Guiding  

Manual guiding is usually done using an eyepiece with an illuminated reticle attached to 

an off axis guider or separate guidescope.  You center a star (or the object being 

photographed) in the reticle and use the buttons on the Deluxe Hand Controller to apply 

guiding corrections to keep the star on the reticle throughout the duration of the exposure.   

Rather than using the Deluxe Hand Controller, you can instead guide with a Losmandy 

Standard Hand Controller plugged into the autoguider port.  The LED of the Standard 

Hand Controller will not normally be lit, but will light up anytime the alarm sounds.  

Using a Standard Hand Controller in the autoguider port has a big advantage for manual 

guiding, in that accidentally pressing opposite directional buttons simultaneously will 

not

result in movement at centering speed, as happens with the Hand Controller in its normal 

socket, or when using the Deluxe Hand Controller.  This reduces the risk of spoiling a 

long exposure photograph due to an accidental key press. 

In either case, you will need to make sure that the Hand Controller is set to either the 

Photographic or All Speeds Mode. 

4.2.3  Connecting an Autoguider to an Older Gemini 

4.2.3.1  Connecting an Autoguider with Relay Output  

Autoguiders with relay outputs (such as the SBIG ST 4) can be connected to the Gemini 

system directly.  Simply connect one side of each of the four relay contacts to the 

Autoguider input common pin, and connect the other side of each relay to the appropriate 

direction input pins of the autoguider port.  Cables are available for most compatible 

autoguiders to plug directly between the autoguider and Gemini. 

Gemini Users Manual 

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