ZWO Off-Axis Guider -OAG

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The ZWO Off-Axis Guider (OAG) makes autoguiding Schmidt-Cassegrain & Refractor Telescopes so much easier.


- Connects your Main Imaging Camera to your Guide Camera without a Guide Scope

- Compatible with All ZWO ASI Cameras

- Eliminates Differential Flexure (Imaging Train Flex)

- Lightweight with a Thickness of only 16.5mm

- Precise 8mm x 8mm Prism

OUR PRICE $209.95
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    Autoguiding is made easy with the ZWO OAG.

    ZWO's innovative Off-Axis Guider (OAG) solves differential flexure (image train flex) by using a large & precise 8mm x 8mm prism to redirect light from your main telescope to your guiding camera. This allows autoguiding to be much more accurate, as it solves guiding errors that result from a guide scope not compensating for any mechanical movement or flex in the main telescope.

    As an added benefit, using an OAG means that you no longer need a guide scope to autoguide. Consequently, you can expect the overall weight of your imaging train to reduce by attaching an OAG. It's also important to note that the Off-Axis Guider is only 16.5mm thick, allowing back focus to remain at a minimum.



    The ZWO Off-Axis Guider (OAG) is compatible with all ZWO ASI Astroimaging Cameras.

    The OAG is designed for use with Schmidt-Cassegrain (SCT) Telescopes & Refractors.


    Connecting the OAG

    This helpful diagram by ZWO illustrates how to integrate the OAG into your imaging train.

    How to attach a ZWO Off-Axis Guider - OAG to an astrophotography camera and telescope for autoguiding


    About ZWO Optical

    Astrophotography has never been easier.

    Established in 2011, ZWO Optical is a fast-growing global astroimaging camera powerhouse based in Suzhou China. They focus on building and innovating ground-breaking CMOS cameras such as the iconic ZWO ASI120MM Monochrome CMOS camera (the first-ever planetary CMOS camera to beat a CCD in the early 2010s). ZWO continues to pioneer new astrophotography technology with revolutionary features to capture exceptional quality of images of space that will last you a lifetime. Today, ZWO cameras are recognised by every passionate astrophotographer and are available in over 25 countries internationally.

    Product Code: ZWO-OAG

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    - ZWO Off-Axis Guider (OAG) Body

    - 1.25" Holder

    - 5mm Extender

    - M42 Adapter

    - M48 Adapter (for Main Imaging Camera)

    - M48-M42 Adapter (for Telescope and Flat Lens)

    - Hexagon Wrench

    ZWO OAG User Guide

    To use the ZWO Off-Axis Guider (OAG) in your imaging train, follow the steps below.


    1. Calculate the required back focus for your imaging train.

    For example, to achieve 55mm back focus, you might use a similar method to the following:

    How to achieve 55mm backfocus

    2. Separate the guiding prism from the OAG before attaching the body of the OAG onto your telescope.

    Attaching the ZWO Off-Axis Guider (OAG) body to a telescope by removing the guiding prism

    3. Insert the prism into the body of the OAG.

    Inserting the prism of the ZWO Off-Axis Guider (OAG) into the body of the ZWO Off-Axis Guider (OAG) which is already attached to a telescope OTA

    4. Mount a guide camera into the OAG prism. 

    Mounting a guide camera into the prism of the ZWO Off-Axis Guider (OAG)

    5. Attach the T2 or M48 adapter to your imaging camera depending on its mount type.

    Attaching a T2 or M48 adapter to a main astroimaging camera to connect it to a ZWO Off-Axis Guider (OAG) 

    6. Lock the three screws on the OAG body to securely mount the camera.

    Locking the three screws on the body of the ZWO Off-Axis Guider (OAG) to securely mount a main astroimaging camera


    The Final Setup

    For an optimal setup, ensure that the prism is not blocking the imaging area. To do so, use the guiding screws to adjust the guide camera's focus.

    It's much easier to ensure that the main imaging camera and guide cameras reach focus at the same position during the day.

    Guide Camera and Main Imaging Camera attached to a telescope OTA using a ZWO Off-Axis Guider (OAG)