The ZWO OAG (Off-Axis Guider) is a compact and lightweight accessory designed for astrophotography, enabling precise guiding without the need for a separate guide scope. This manual, version 2.0, released in August 2019, provides a comprehensive overview of the OAG's features, connection procedures, and maintenance guidelines.
Function Description
The primary function of the ZWO OAG is to allow an imaging camera and a guide camera to share the same optical path, eliminating the flexure and weight issues often associated with traditional guide scope setups. By diverting a small portion of the main telescope's light path to a guide camera, the OAG enables real-time tracking of celestial objects, crucial for long-exposure astrophotography. This integrated guiding solution ensures that the guide camera sees the same field of view as the main imaging camera, leading to more accurate guiding and sharper images. The OAG is particularly beneficial for setups where minimizing weight and complexity is important, or where a guide scope might introduce unwanted flexure. It is designed to be fully compatible with all ZWO ASI cameras, offering a versatile guiding solution for a wide range of astrophotography setups.
Important Technical Specifications
- Thickness: The OAG boasts a slim profile with a thickness of 16.5mm, making it suitable for setups with limited back focus. This compact design helps maintain the overall optical train length, which is critical for achieving focus with various cameras and telescopes.
- Prism Size: It features a large 8x8mm prism, which is responsible for diverting light to the guide camera. The generous size of the prism ensures that sufficient light is captured for guiding, even with fainter guide stars, enhancing guiding sensitivity and reliability.
- Compatibility: The OAG is fully compatible with all ZWO ASI cameras. This broad compatibility ensures that users of ZWO's extensive range of imaging and guiding cameras can seamlessly integrate the OAG into their existing setups.
- Adapters: The OAG comes equipped with both M42 and M48 adapters, providing flexibility for connecting to various telescopes and imaging cameras. The inclusion of these common thread sizes simplifies the integration process, allowing for direct attachment to most astrophotography equipment.
- Secure Connections: The design incorporates hexagon socket head cap screws to prevent looseness, ensuring a stable and secure connection between the OAG, cameras, and telescope. This robust fastening mechanism minimizes any potential for movement or misalignment during imaging sessions.
- Included Components: The package includes the OAG body (with a 1.25" holder, 5mm extender, and M42 adapter pre-installed), an M48 adapter for the main imaging camera, an M48-M42 adapter for the telescope, and a hexagon wrench for adjustments. These components provide a complete solution for setting up the OAG.
- Back Focus Considerations: For ASI cameras with a back focus distance of 12.5mm, a 5mm extension is provided. This ensures that the guide camera can reach focus when used with the OAG. However, if using an ASI174 for guiding, this extension may not be necessary, highlighting the importance of checking specific camera requirements.
Usage Features
- Integrated Guiding: The OAG connects directly between the main imaging camera and the telescope, allowing the guide camera to tap into the main optical path. This eliminates the need for a separate guide scope, reducing overall weight, potential flexure, and setup complexity.
- Prism Adjustment: The OAG features an adjustable prism, allowing users to unlock a screw and precisely position the prism. This adjustment is crucial to ensure that the prism does not obstruct the imaging train while still allowing a guide star to be found. The ability to fine-tune the prism's position helps optimize both imaging and guiding performance.
- Guide Camera Focus Adjustment: A dedicated screw allows for adjusting the focus of the guide camera. Users can unlock this screw, achieve focus for the guide camera, and then fix it in place. This independent focus adjustment ensures that the guide camera can achieve sharp focus regardless of the main imaging camera's focus position.
- Camera Mounting: The imaging camera is mounted onto the OAG in the correct position and secured with three locking screws. It is critical to ensure that the prism does not block the imaging area of the main camera during this process.
- Daytime Setup Recommendation: It is recommended to perform the initial setup and focus adjustments during the daytime. This allows users to easily verify that both the imaging camera and the guiding camera can reach focus simultaneously, streamlining the process for nighttime observations.
- Helical Focuser Recommendation: For more convenient guiding experience, especially when fine-tuning focus, the manual recommends pairing the OAG with a ZWO 1.25-inch Helical Focuser. This accessory, with its 6mm stroke and 0.1mm adjustment accuracy, can greatly simplify achieving precise focus for the guide camera.
Maintenance Features
- Servicing and Repairs: ZWO offers repair and servicing options for the OAG. Customers can contact info@zwoptical.com for assistance. For products purchased through local dealers, the dealer is responsible for providing customer service and support.
- Warranty: The ZWO OAG comes with a 2-year warranty. During this period, ZWO provides free repair service or replacement if the product fails to function under normal use. This warranty covers manufacturing defects and ensures peace of mind for users.
- Post-Warranty Support: After the warranty period, ZWO continues to offer repair support and service on a charged basis, ensuring that users can maintain their OAG for an extended period.
- Warranty Exclusions: The warranty does not cover damage resulting from abuse, misuse, falls, or transportation failures after purchase. This clarifies the scope of the warranty and emphasizes the importance of proper handling and care of the device.
- Shipping Costs: Customers are responsible for paying shipping costs when sending the camera back for repair or replacement, whether under warranty or for charged services.
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