Astrodon Off-Axis Guider MonsterMOAG (Manual Off-Axis Guider) allows you to guide your telescope to obtain sharp, round stars by guiding in front of your filters using unfiltered light in the same optical beam as your imaging camera.  This is particularly important for practical use of narrowband filters. It also eliminates potential differential flexure if you guide with a separate guide scope. With modern, automated data acquisition programs, framing your imaging target and placing a guide star in the guide camera is simple and no longer an issue, particularly if you have a remotely-controlled camera rotator.

MonsterMOAG™ (MMOAG) is specifically designed to accommodate the larger CCD imaging detectors such as the KAF16803E and KAF9000E and larger.  Detectors up to 48mm x 48mm can be fully illuminated.  Furthermore, at 1.25″ thick, it has one of the thinnest backfocus for an OAG available, making  MonsterMOAG™ an ideal choice for systems with minimal backfocus, such as the Takahashi FSQ106N refractor.  However, it is strong enough to handle heavy loads from larger cameras and filter wheels.

When installed, the MonsterMOAG becomes a fixed part of your optical train along with your camera and filter wheel.  When you rotate your camera at the back of your telescope, these three components will rotate together.  This means that the guide camera location will be fixed relative to the imaging camera.  You define this once as your Field-Of-View-Indicator (FOVI) in programs like Software Bisque’s TheSkyX.   Then you can frame your target while ensuring that the guide camera has a star to guide on.

The new MMOAG-1,2,3,4  introduces the capability of attaching up to 4 guide ports to the MonsterMOAG. This was accomplished by making the body square and adding a hole on each side for insertion of the pick-off prism from the guide port assembly.  Thus, one possibility could include one guide camera and one 1.25″ eyepiece, for example.  Any unused guide port will be shipped with a removable black metal plate.  Extra guide port assemblies can be ordered at a later date. The thickness (backfocus) and adapters are the same as before.  ​

Adapters: The MonsterMOAG is sold without telescope and camera / filter wheel adapters.  We offer (separately) a series of standard adapters that connect common devices to the guider body, however it is common to need a custom adapter to get everything connected properly.  For this, we recommend using Precise Parts to design and make the adapters you need.  You can see our video discussion about using Precise Parts here.

Backfocus Calculations: In order to get the guide camera and main detector both to come to focus properly the camera side connection lengths need to be calculated and the corresponding stock adapter selected or custom adapter made.   A detailed discussion of how this simple calculation is performed can be found here.