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ZWO 22.5mm M42 to M48 Extender
The ZWO 22.5mm M42 Male to M48 Female Extender is a purpose-built adapter designed to achieve the standard 55mm back focus when connecting a ZWO ASI2600MM Pro camera to a 7x36mm ZWO Electronic Filter Wheel. This adapter's precise 22.5mm length bridges the exact spacing gap required in this popular imaging train. It converts the EFW's M42 thread to the common M48 thread used by most correctors, simplifying your connection chain.
A 55mm Back Focus Solution for the ASI2600MM
This 22.5mm extender is the key component for building a compact, rigid imaging train with the ASI2600MM Pro and 36mm EFW. By using this adapter, you can reach the critical 55mm back focus distance without needing to add a ZWO Off-Axis Guider into the optical path. This creates a shorter, lighter setup ideal for portable rigs or mounts where moment arm is a concern.
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Optimized Spacing: Provides the exact 22.5mm needed for the ASI2600MM and 7x36mm EFW combination to total 55mm of back focus.
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Streamlined Imaging Train: Eliminates the need for an OAG-L in this specific configuration, reducing complexity and weight.
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Rigid Connection: A single, solid adapter prevents flexure better than a stack of multiple thin spacers.
M42 and M48 Threads with ASI2600MM Installation
The adapter features male M42x0.75 threads on one side that connect directly to the ZWO EFW. The opposite side has female M48x0.75 threads, ready to attach to your telescope's field flattener or reducer. For proper installation with the ASI2600MM camera, the camera's sensor tilt plate must first be unscrewed and removed; the extender and filter wheel are then attached using the same screws, shortening the filter-to-sensor distance as required.
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What is the primary purpose of the ZWO 22.5mm M42-M48 extender?
This extender is specifically designed to set the correct 55mm back focus distance when pairing a ZWO ASI2600MM Pro camera with a ZWO 7x36mm Electronic Filter Wheel (EFW). It provides the exact 22.5mm of spacing needed for this combination.
How do I install the ZWO 22.5mm extender with an ASI2600MM Pro?
To achieve the correct spacing, you must first unscrew and remove the sensor tilt plate from the front of the ASI2600MM Pro camera body. You then use the screws from the tilt plate to attach the filter wheel and this 22.5mm extender directly to the camera.
Can I use the ZWO OAG-L with this 22.5mm extender?
No. This 22.5mm extender is designed as an alternative to achieve 55mm of back focus in configurations without an Off-Axis Guider. If you need to use an OAG-L, you will need a different combination of spacers.
What are the thread types on the ZWO 22.5mm extender?
The extender has male M42x0.75 threads on the side that connects to the filter wheel and female M48x0.75 threads on the side that connects to the telescope's corrector or flattener.
Will the ZWO 22.5mm extender work with my telescope's M48 corrector?
Yes. The female M48 threads on this extender are the standard "wide T-thread" size used by most 2-inch field flatteners, reducers, and coma correctors, ensuring a direct and secure connection.
Can I use this 22.5mm extender for other cameras or spacing needs?
While designed for the ASI2600MM Pro, it can be used in any imaging train where you need exactly 22.5mm of spacing and need to adapt a male M42 thread to a female M48 thread. Always verify your own back focus calculations before using it in other configurations.
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| SKU |
ZWO-M42-M48-22.5 |
| Camera-Side Thread |
M42 x 0.75 Male |
| Telescope-Side Thread |
M48 x 0.75 Female |
| Optical Length |
22.5 mm |
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22.5 mm M42 Male to M48 Female Extender
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- ZWO 2-Year Limited Warranty
