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ZWO OAG

ZWO OAG

by ZWO
SKU ZWO-OAG
$128.00 USD - $128.00 USD
$128.00 USD
$128.00 USD - $128.00 USD
$128.00 USD
Price Match Policy!
  • Eliminates Differential Flexure
  • Reduces Overall System Weight
  • Includes 1.25" Guide Camera Holder
  • M48 and M48 to M42 Adapters Included
  • Spacer and Hex Key Included
12 in stock
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO OAG Off-Axis Guider

    The ZWO OAG integrates guiding directly into your main optical path using an included 1.25” holder for your guide camera. It ships with a spacer, an M48 adapter and an M48 to M42 adapter for connecting to your imaging train, effectively eliminating the differential flexure that can plague separate guidescope setups.

    End Differential Flexure with a 1.25" Integrated Guider

    The ZWO OAG solves the most persistent problem in long-exposure astrophotography: differential flexure. By using a prism to pick off a small portion of the light from your main telescope's imaging cone, it ensures your guide camera and imaging camera see the exact same minute movements. Any tube flexure, mirror flop, or mount shift is seen by both cameras simultaneously, resulting in perfectly round stars even at long focal lengths.

    This design makes a separate, heavy guidescope unnecessary, reducing the overall weight and complexity of your rig. The OAG includes a standard 1.25” holder, making it compatible with a wide range of popular autoguiding cameras.

    Fine-Tune Focus with the Included Spacer and Adapters

    Achieving simultaneous focus between your main imager and guide camera is critical. The ZWO OAG kit includes a versatile set of adapters to manage the precise spacing required. The package contains an M48 adapter, an M48 to M42 adapter and a spacer.

    • Spacer: ZWO includes a spacer ring with the OAG; ZWO does not state its thickness.
    • Adapter Suite: With the included M48 and M48 to M42 adapters, you have the flexibility to connect to nearly any imaging train configuration right out of the box.

    ZWO OAG vs. Traditional 50mm Guidescopes

    While a 50mm guidescope offers a wider field of view for finding a guide star, the OAG provides superior guiding accuracy where it matters most.

    • Zero Flexure: The ZWO OAG physically eliminates differential flexure, a mechanical problem that guiding software cannot correct. This is the single largest source of elongated stars in systems using a separate guidescope.
    • Reduced Weight and Better Balance: By removing the guidescope, mounting rings, and dovetail bar, you reduce the payload on your mount. This improves tracking and allows the mount to perform more efficiently.
    • Long Focal Length Precision: For Schmidt-Cassegrains and Ritchey-Chrétiens, the OAG guides at the same image scale as your main camera. This allows for far more precise corrections than a short focal length guidescope can deliver, leading to fundamentally sharper images.

  • Why should I use the ZWO OAG instead of a guidescope?

    The primary reason is to eliminate differential flexure. This is any small mechanical shift between your main telescope and your guidescope that causes trailing stars, even with perfect guiding. The ZWO OAG uses one optical path for both cameras, making this problem impossible. It also reduces the weight and complexity of your setup.

    Will the ZWO OAG work with my Celestron EdgeHD 8" and an ASI533MC Pro camera?

    Yes, this is an excellent combination. Long focal length systems like the EdgeHD 8" are the most susceptible to differential flexure, making the ZWO OAG the ideal guiding solution. The included M48 and M48 to M42 adapters will allow you to connect the OAG to your camera and the telescope's reducer or focuser.

    How do I focus the guide camera with the ZWO OAG?

    First, achieve sharp focus with your main imaging camera. Then, loosen the thumbscrew on the 1.25" holder and slide your guide camera up or down until the stars in your guiding software are also sharp. The goal is to make the distance from the prism to the guide sensor equal to the distance from the prism to the main imaging sensor.

    I'm imaging the Pelican Nebula (IC 5070). Will I have trouble finding a guide star?

    The Pelican Nebula is in a dense region of the Milky Way, so finding a guide star with the ZWO OAG should be straightforward. The main trade-off of an OAG is a smaller field of view for finding stars compared to a guidescope. In star-poor regions, you may need to rotate your camera to place a suitable guide star onto the prism, but for most deep-sky targets, this is not an issue.

    What adapters come included with the ZWO OAG?

    The ZWO OAG comes with a comprehensive set of adapters to fit most imaging trains. Included are an M48 adapter, an M48 to M42 adapter and a spacer.

    Can I use a non-ZWO guide camera with this OAG?

    Yes. The ZWO OAG includes a standard 1.25” holder. Any guide camera with a 1.25" nosepiece form factor will fit and can be used for autoguiding.

  • SKU ZWO-OAG
    Warranty 2 Years
    Optical length 16.5 mm
    Prism size 8 x 8 mm
    Recommended main camera ASI cameras with APS-C sensor or smaller
    Recommended guide camera ASI Mini camera
    Compatible filter wheels 1.25", 2" and 36mm EFW
    Weight 181 g
    Telescope-Side Connection M48x0.75 female

    • ZWO OAG Body

      × 1

    • Spacer

      × 1

    • M48 Adapter

      × 1

    • M48 to M42 Adapter

      × 1

    • Hexagon Wrench

      × 1

  • ZWO 2-Year Limited Warranty