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ZWO M54(M)-M48(F) Adapter - 21mm

ZWO M54(M)-M48(F) Adapter - 21mm

by ZWO
SKU ZWO-M54-M48-21
$25.00 - $25.00
$25.00
$25.00 - $25.00
$25.00
Price Match Policy!
  • Adds exactly 21mm of optical path length
  • Connects M54 male threads to M48 female threads
  • Standard 2-inch filter threading on the M48 side
  • Black anodized aluminum construction minimizes reflections
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • ZWO M54(M)-M48(F) Adapter - 21mm

    The ZWO M54 to M48 adapter provides a fixed 21mm of extension, bridging the connection between full-frame ZWO cameras with M54 threads and correctors or accessories with standard M48 male threads. This adapter is a critical component for achieving precise back focus in imaging trains that require specific, non-standard spacing to reach the sensor at the correct distance.

    Achieving Precise 21mm Back Focus Spacing

    In astrophotography, hitting the exact back focus distance specified by your flattener or reducer is non-negotiable for a sharp, flat field. This adapter adds exactly 21mm of length, allowing you to fine-tune the spacing in your optical train. It's an essential tool when your camera, filter wheel, and off-axis guider combination doesn't add up to the required 55mm or other custom back focus distances.

    Connecting M54 Cameras to M48 Correctors

    ZWO's full-frame cameras use a wide M54 thread to minimize vignetting, while many flatteners, reducers, and correctors terminate in the M48x0.75 standard. This ZWO adapter screws into the camera with its M54 male thread and presents an M48 female thread for your corrector, ensuring broad compatibility across your equipment.

    • M54 Male Thread: Connects directly to a ZWO full-frame camera with M54 threads.
    • M48 Female Thread: Accepts standard 2-inch filters and connects to the M48 male thread of your corrector, flattener, or reducer.
    • Durable Construction: Machined from black anodized aluminum to reduce internal reflections and provide a rigid connection that prevents flexure.

    ZWO's 21mm vs. Other M54-M48 Adapters

    ZWO offers a range of M54 to M48 adapters, and choosing the correct length is critical. The 21mm adapter is not a universal solution but a specific tool for a specific spacing requirement.

    • vs. ZWO 16.5mm Extender: The two lengths are often used together. In a train without an off-axis guider, a ZWO camera with 17.5mm of back focus, a 21mm extension, and the 16.5mm M48 extender give 17.5 + 21 + 16.5 = 55mm. Whether you need one, the other, or both depends entirely on the optical path length of the other components in your imaging train.
    • Fixed Length Trade-off: Unlike a variable spacer, this 21mm adapter provides a fixed, rigid extension. This rigidity is a benefit, as it eliminates potential tilt, but it means you must calculate your required back focus precisely before purchasing.

  • What is the main purpose of the ZWO M54-M48 21mm adapter?

    This adapter serves two primary functions: it connects a camera with M54 threads to a corrector with the more common M48 male thread, and it adds a precise 21mm of spacing to help you achieve the correct back focus for your imaging system.

    How do I use the ZWO 21mm adapter to achieve 55mm back focus with my ZWO camera?

    You would use this 21mm adapter as part of a calculated imaging train. With a ZWO full-frame camera that has 17.5mm of back focus, this adapter brings the total to 38.5mm. Adding a 16.5mm M48 extender completes the train at 17.5mm + 21mm + 16.5mm = 55mm. If you add a filter wheel or off-axis guider, subtract its optical length and adjust your other spacers accordingly.

    Can I thread a 2-inch filter into the ZWO M54-M48 adapter?

    Yes. The female M48 side of the adapter is threaded to accept standard 2-inch astronomy filters (M48x0.75). This allows you to place a filter within the adapter itself, which can be useful in specific imaging configurations.

    Will this 21mm adapter connect my Sky-Watcher Quattro corrector to a full-frame ZWO camera?

    Yes, if your Sky-Watcher Quattro coma corrector terminates in an M48 male thread. The adapter's M48 female side threads onto the corrector and its M54 male side threads into the camera, all while adding 21mm to the optical path.

    Is the ZWO M54-M48 21mm adapter compatible with non-ZWO equipment?

    Absolutely. As long as your equipment uses the standard M54x0.75 male thread and M48x0.75 female thread conventions, this adapter will work regardless of the brand. It is a universal part for connecting these two common astronomy thread sizes.

    Why would I choose this fixed 21mm adapter instead of a variable spacer?

    A fixed adapter like this 21mm ZWO model offers superior rigidity and eliminates the risk of tilt that can be introduced by some variable or helical spacers. When you know the exact spacing you need, a fixed adapter is the most stable and reliable way to achieve it.

  • SKU ZWO-M54-M48-21
    Connector Side A M54 Male (camera side)
    Connector Side B M48 Female (2" Filter Thread, corrector side)
    Length 21 mm

    • ZWO M54 to M48 Extension - 21 mm

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  • ZWO 2-Year Warranty