The off-axis guider offers your a simple method of autoguiding your telescope for astrophotography. There is no need to mount a guidescope, rather a guiding camera tracks stars which are deflected from the telescope's optical path close to the imaging camera's sensor.
An advantage of this method is that the guide stars are located within the area of sky close the astrocamera. So you track the stars which are next to your desired object and avoid errors caused by differential flexure and guidescope misalignment.
The off-axis-guider for cameras with an external Mark II filter wheel is equipped with an M68×1 thread on the telescope side at a distance of 61.5 mm from the detector. On the camera side, there are mounting holes for connection to Moravian C3/G3 cameras with an external Mark II filter wheel.
A 1.25" plug-in sleeve is available for the tracking camera, and cameras with a CS mount connection can also be used via adaptors. Important: If the working distance deviates significantly from 61.5 mm, it may not be possible to focus the tracking camera!
The mirrors that deflect the light to the tracking camera have a cross-section of 10 × 7 mm when viewed from the front (the mirror dimensions are 10 × 10 mm, but the mirrors are angled at 45 degrees). This is sufficient for tracking cameras with very large 2/3" format detectors without causing significant vignetting (the smallest detectors used in G0/G1 tracking cameras are 1/3" format, but many tracking cameras use 1/4" or even smaller chips).
Like all off-axis-guiders with Mark II adaptors, this OAG also has tiltable collimation screws. These adjustment screws allow you to collimate the sensor plane to the flat image field.
