ZWO OAG-L Off-Axis Guider for Astrophotography

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Don't have room for a guidescope on your rig? Well, the ZWO Off-Axis Large Guider is here to save the day.
Our Product #: ZWOOAGL
ZWO Product #: OAG-L
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Product Description

The ZWO Large Off-Axis guider is your solution to adding a guide system to your imaging rig.  You won't need another guidescope and rings added to the equation.  Just drop this 17.5mm thick guider in your train and away you go.  The machined aluminum body is black anodized to provide a durable long lasting finish.

The ZWO OAG is compatible with all ZWO ASI cameras.  It comes with adapters for both M42 and M48.  Just remember to calculate the 17.5 mm thickness into your avialable back focus of your imaging train.  The prism is fairly large at 12mm x 12mm giving you a good piece of sky to guide from.  The larger clear aperture brings a wider field of view to your guiding. It is easy to use, and suitable for users who are interested in long focal length photography.  


  1. Lightweight and exquisite, 17.5mm thickness.
  2. Prism size: 12*12mm.
  3. The effective light-passing aperture is 11.7mm*8.3mm.
  4. Can be used to connect the main camera and guide camera simultaneously. No guide telescope required.
  5. Packaged with an M48 sensor tilt plate (5mm)

Operating Guide:

  1. For guiding, OAG-L can only work with ASI Mini cameras like ASI174MM Mini, ASI290MM Mini and ASI120MM Mini.
  2. Considering the large prism size, we don’t recommend you use OAG-L with telescopes whose clear aperture is smaller than M48.
  3. Yet it is recommended to use with 2” EFW or 7x36mm EFW, and with APS-C cameras (ASI2600) or full-frame cameras (ASI6200/2400). The large clear aperture supports full-frame cameras without vignetting.
  4. The major differences between OAG-L and M68 OAG are about the prism size and the threads. OAG-L removed the inner threads so you can directly use the screws to connect it to other equipment.
  5. If the thread of your telescope side is M48, then you don’t need to remove the M48 sensor tilt plate coming with OAG-L. On the contrary, you need to remove it and use some other sensor tilt plate at the corresponding thread of your telescope.
  6. While adding OAG-L into your optical train, please make sure the prism won’t block the camera sensor.
  7. You can use the guiding screw to adjust the guiding camera’s focus length. Please make sure the distances from the prism to the main camera and to the guide camera are the same. To ensure the result, it is better to do this during the daytime for the adjustment will be very difficult at night.

Tech Details

Warranty 2 years


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