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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.
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 – 7.5 mm
Baader Planetarium M54 Extension Tube – 7.5 mm
Baader Planetarium M54 Extension Tube – 7.5 mm

Baader Planetarium M54 Extension Tube – 7.5 mm

by Baader Planetarium
SKU BAA-2958707
$50.00 - $50.00
$50.00
$50.00 - $50.00
$50.00
Price Match Policy!
  • Provides 7.5 mm of Fixed Extension
  • M54 x 0.75 Male and Female Threads
  • Essential for Correcting Back Focus
  • Matte Black Interior to Reduce Reflections
  • Maintains Rigidity in the Imaging Train
2 in stock
Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box

  • M54 Extension Tube – 7.5 mm

    This M54 Extension Tube provides a fixed, non-flexing 7.5 mm of spacing, a critical component for achieving the precise back focus required by field flatteners, coma correctors, and focal reducers. It is designed for modern imaging trains that utilize the large M54 standard to connect full-frame cameras and large-format accessories without vignetting.

    Achieving Precise 7.5 mm Back Focus with M54 Threads

    Achieving sharp, coma-free stars from corner to corner depends entirely on setting the exact distance between your corrector lens and sensor plane. This M54 extension tube adds exactly 7.5 mm to your imaging train, allowing you to precisely dial in the required back focus. Using a fixed-length tube provides a more rigid and tilt-free connection than many variable extension systems, which is crucial for maintaining optical alignment.

    • M54 x 0.75 Threads: Connects seamlessly with a wide range of full-frame cameras, filter wheels, and off-axis guiders that use this large-aperture standard.
    • Anti-Reflection Design: The interior is blackened and baffled to absorb stray light, preventing internal reflections from degrading image contrast.
    • Solid Mechanical Connection: Machined from aluminum, this spacer ensures your camera and corrector remain perfectly parallel, preventing sensor tilt that can ruin an otherwise perfect image.

  • What is the primary use for this M54 Extension Tube – 7.5 mm?

    Its primary purpose is to set the correct back focus distance in an astrophotography imaging train. Most focal reducers and field flatteners require a specific spacing to the camera sensor (typically 55 mm), and this 7.5 mm tube is used to fill a small, precise gap to achieve that target distance.

    How do I know if I need a 7.5 mm M54 extension for my specific setup?

    You need to calculate your current back focus and compare it to what your corrector requires. Add up the optical path length of all components behind your corrector (e.g., filter wheel, off-axis guider, camera flange distance). If the total is, for example, 47.5 mm and your corrector needs 55 mm, this 7.5 mm extension tube is the perfect component to make up the difference.

    Can I stack the 7.5 mm M54 extension tube with other spacers?

    Yes, you can stack multiple extension tubes. However, for maximum rigidity and to minimize the potential for sensor tilt, it is always best to use a single extension tube of the correct length whenever possible. Stacking several small spacers can introduce slight misalignments.

    Why use a fixed 7.5 mm M54 tube instead of a variable spacer?

    A fixed extension tube like this one offers superior rigidity. Variable spacers, while flexible, can sometimes introduce a small amount of tilt or flexure into the imaging train, especially with heavier cameras. A fixed tube provides a solid, stable, and repeatable connection, which is critical for consistent, sharp results.

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

    No. The M54 thread standard is specifically designed to provide a large, clear aperture to fully illuminate full-frame sensors (36x24 mm) without vignetting. This extension tube maintains that clear aperture throughout its length, ensuring the light cone from your corrector reaches the entire sensor.

    Is the 7.5 mm M54 extension tube compatible with imaging trains on Schmidt-Cassegrain telescopes?

    Yes, absolutely. Many focal reducers designed for SCTs, such as the Celestron f/7 reducer for EdgeHD models, use M54 threads and require precise back focus. This extension tube is an ideal component for building out the correct spacing between the reducer and your camera.