Astronomy Specialist



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The Large-sized QHYCCD off-axis guider is designed for QHY cameras with large 36 x 24mm, 37 x 37mm, and 48 x 36mm sensors.

Precision Connection, No Deflection

The main purpose of the off-axis guider (OAG) is to use the same optical path as the main camera when guiding during astrophotography. Using an OAG avoids the problem of differential flexure that can occur when using a separate guide scope. With an OAG, part of the image is picked-off from the edge of the imaging circle which does not block the main CCD. Off-axis guiding provides more accurate guiding and sharper final images.

The QHY off-axis guiders have an 8mm x 8mm multi-coated prism that picks off the beam for the guide camera. The position of the prism can be adjusted as needed and locked down. The main camera connects to the OAG with six 3mm screws that ensure connection accuracy and parallelism, providing a reliable and secure mechanical connection.

QHY Off-Axis Guider for Large Cameras and Filter Wheels

With a diameter of 68mm, this large-sized version of the QHY OAG works with M60x0.75 adapters. It supports cameras with large 36 x 24mm, 37 x 37mm, and 48 x 36mm sensors. This OAG also works with the QHYCFW3-XL Extra-Large filter wheel.

Precise Easy Focusing

Each QHY OAG includes a non-rotating helical 1.25" focuser with a 6mm range to help focus an image on your guide camera. When using the QHY5II and QHY5III, the position of these cameras can be further adjusted in the OAG itself to accommodate a wide range of back focus.



  • QHYOAG-L Large
  • 2x M42 x 0.75 3mm adapter plates (020080 & 020081)
  • 2x M54 x 0.75 3mm adapter plates (020078 & 020079)
  • Attachment screws


Telescope connection
Maximum free aperture 58mm
Connection screws
6 x M3, 68mm apart
Sensor size compatibility 36x24mm, 37x37mm, 48x36mm
Compatible products
Guide camera interface
Optical thickness 10mm without adapter, 13mm with adapter


QHY OAG Off Axis Guider Large schematics


QHYOAG-L (Large) schematic.


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