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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader Planetarium M54 Extension Tube – 5 mm
Baader Planetarium M54 Extension Tube – 5 mm
Baader Planetarium M54 Extension Tube – 5 mm

Baader Planetarium M54 Extension Tube – 5 mm

by Baader Planetarium
SKU BAA-2958705
$49.00 - $49.00
$49.00
$49.00 - $49.00
$49.00
Price Match Policy!
  • 5 mm Fixed Extension: Adds a precise, non-flexing 5 mm of optical path length to your imaging train.
  • M54 Thread Standard: Connects seamlessly with M54 threaded accessories, common in full-frame imaging trains.
  • Rigid Construction: Provides a solid, tilt-free connection that is often more stable than variable-length adapters.
  • Internal Baffling: Features a matte-black interior to absorb stray light and maximize image contrast.
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • M54 Extension Tube – 5 mm

    The M54 Extension Tube adds exactly 5 mm of fixed spacing to any optical train using the M54 thread standard, making it an essential component for achieving the precise back focus required by modern field flatteners and focal reducers. By filling a small gap in your imaging train, this 5 mm ring ensures your corrector-to-sensor distance is set correctly, eliminating elongated stars at the edge of the frame.

    Achieve Critical Back Focus with 5 mm of Precision Spacing

    Most flatteners and reducers require a specific distance to the sensor, typically 55 mm, to deliver a perfectly flat field. This 5 mm extension tube is the ideal solution for bridging the final gap when your camera and other accessories don't add up to the exact spacing needed. Its fixed-length, rigid design prevents the flexure and tilt that can compromise image quality in adjustable spacers, ensuring your optical alignment remains perfect.

    M54 Threads: A Wide 54 mm Path for Full-Frame Sensors

    For imagers using full-frame or other large-format sensors, the M54 thread standard is critical for preventing vignetting. Unlike smaller M42 or M48 threads that can constrict the light cone, the larger 54 mm diameter of this extension provides an unobstructed path to the sensor. This ensures even illumination from corner to corner, preserving the faint details in wide-field targets like the Andromeda Galaxy (M31) or the North America Nebula (NGC 7000).

  • What is the primary use for the M54 Extension Tube – 5 mm?

    Its primary use is to add a precise 5 mm of length to an M54-threaded imaging train. This is crucial for achieving the exact back focus distance (typically 55 mm) required by field flatteners, coma correctors, and focal reducers to ensure sharp, point-like stars across the entire field of view.

    Why would I use a fixed 5 mm M54 extension tube instead of a variable spacer?

    A fixed 5 mm extension tube offers superior rigidity and stability. Variable spacers can sometimes introduce slight tilt or flexure into the optical train, which can degrade image quality, especially with heavy cameras. When you know you need exactly 5 mm, a fixed tube provides a more robust and reliable connection.

    Will this 5 mm M54 extension tube cause vignetting with my full-frame camera?

    No, quite the opposite. This extension uses the M54 standard specifically to prevent vignetting on large sensors, including full-frame (36x24 mm) and larger formats. The wide diameter ensures the light cone from the telescope is not clipped before it reaches the sensor corners.

    How do I know if I need this 5 mm M54 extension tube for my imaging setup?

    You need to calculate your current back focus. Start with the required spacing for your flattener/reducer (e.g., 55 mm). Then, subtract the flange distance of your camera (e.g., 17.5 mm for a ZWO camera) and the thickness of any other accessories like filter wheels or off-axis guiders. If the remaining gap is 5 mm, this extension is the perfect solution.

    Can I stack multiple 5 mm M54 extension tubes?

    Yes, you can stack multiple extensions to achieve different lengths (e.g., two tubes for 10 mm of spacing). However, for longer distances, it is generally recommended to use a single extension of the correct length to minimize the number of threaded connections and potential for tilt.

    My flattener requires 55 mm of back focus and my ASI camera has 17.5 mm. How does this 5 mm M54 tube help?

    In a common ZWO imaging train, you might have a 17.5 mm camera flange, a 21 mm off-axis guider, and a 16.5 mm M48-M54 adapter, totaling 55 mm. If you replace the 16.5 mm adapter with an 11 mm version to get closer to the sensor, you create a 5.5 mm gap. This 5 mm extension tube would then be used to get you to 54.5 mm, which is often well within the tolerance for sharp stars.

  • This product is covered by a standard 1-year warranty against manufacturing defects.