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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 M48 Extension Tube - 5mm

Baader M48 Extension Tube - 5mm

by Baader Planetarium
SKU BAA-2958605
$35.00 - $35.00
$35.00
$35.00 - $35.00
$35.00
Price Match Policy!
  • Adds a fixed 5mm of optical path length
  • Standard M48 x 0.75 filter threads
  • Essential for precise back focus adjustment
  • Rigid, non-flexing aluminum construction
  • Matte black interior to prevent reflections
1 in stock
Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Baader M48 Extension Tube - 5mm

    The Baader M48 Extension Tube provides a simple, rigid solution for adding exactly 5mm of length to your imaging train. For astrophotographers using flatteners, reducers, or coma correctors, achieving the manufacturer's specified back focus distance is not optional—it is the single most important factor for achieving sharp stars across the entire sensor, and this 5mm spacer is a critical tool for dialing in that distance perfectly.

    Achieving Critical 5mm Back Focus Spacing

    Modern imaging systems require micrometer-level precision. This M48 extension tube is designed to fill a small, fixed 5mm gap in your optical path. Unlike variable spacers that can introduce tilt, this fixed-length tube ensures your camera remains perfectly orthogonal to the light path, preserving the flatness of your field.

    • Standard M48 Threads: Features M48 x 0.75 female and male threads for seamless integration with 2-inch filter wheels, off-axis guiders, and dedicated astronomy cameras.
    • Fine-Tune Your Spacing: Use this 5mm tube in combination with other spacers to precisely match the required back focus of your specific corrector, eliminating field curvature and distorted stars at the edge of your images.
    • Solid, Flex-Free Connection: Machined from aluminum, it provides a robust connection that prevents sag or tilt, which is especially important when supporting heavier camera packages.

  • What is the primary use for the Baader M48 5mm Extension Tube?

    Its primary use is to fine-tune the back focus distance between an optical corrector (like a field flattener or coma corrector) and the camera sensor. Most correctors require a very specific distance, often 55mm, and this 5mm tube helps you achieve that exact spacing when your existing adapters leave a small gap.

    My stars are elongated at the edge of my images. Could a Baader M48 5mm Extension Tube help?

    Yes, this is a classic symptom of incorrect back focus. If your current spacing is slightly too short, adding this 5mm tube could be the exact correction needed to flatten the field and produce sharp, round stars from corner to corner. You should measure your current optical path to confirm if you need to add 5mm.

    Will the Baader M48 5mm Extension Tube thread into my 2-inch filters?

    Yes. The M48 x 0.75 thread pitch is the standard for 2-inch astronomy filters. You can thread this extension tube directly onto a filter or into any accessory that uses M48 threads, such as a filter drawer or the nosepiece of many cameras.

    Can I stack multiple Baader M48 5mm Extension Tubes?

    Absolutely. You can stack multiple tubes to achieve custom lengths. For example, stacking two of these would give you a 10mm extension. This allows for a modular approach to building out the exact spacing your optical system requires.

    Why use a fixed 5mm Baader tube instead of a variable spacer?

    While variable spacers offer flexibility, they can sometimes introduce optical tilt if not locked down perfectly square. A fixed extension tube like this Baader 5mm provides a more rigid, stable, and perfectly collimated connection, eliminating a potential source of image degradation.

    Will this 5mm Baader M48 Extension Tube cause vignetting with my full-frame camera?

    No. The M48 thread standard (also known as a "wide" T-ring) is specifically designed to provide a larger clear aperture than the older T2 (M42) standard. It is intended for use with full-frame (24x36mm) sensors and will not cause additional vignetting.

  • Extension Length 5mm
    Thread Type M48 x 0.75
    Gender Male one side, Female the other
    Net weight (kg) 0.01
    Compatible Brands Baader Planetarium
    Clamping System no clamp
    Inner Diameter / Clear Aperture (mm) 45 mm
    Outer Diameter 53 mm
    Usage Adjusting the distances of accessories with M48 thread
    Outer Connection (eyepiece/-camera-sided) M48
    Inner Connection (lens sided) M48
    Adapters Family M48 System

    • Baader M48 Extension Tube - 5mm

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  • Baader Planetarium Warranty