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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 M68 Extension Tube - 40mm

Baader M68 Extension Tube - 40mm

by Baader Planetarium
SKU BAA-2458204
$102.00 - $102.00
$102.00
$102.00 - $102.00
$102.00
Price Match Policy!
  • 40mm Fixed Extension Length
  • M68 x 1mm Male and Female Threads
  • Provides Rigid, Flexure-Free Spacing
  • Component of the Baader M68 Tele-Compendium System
  • Blackened Internals to Reduce Stray Light
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Baader M68 Extension Tube - 40mm

    The Baader M68 Extension Tube provides a rock-solid 40mm of spacing for advanced imaging trains built around the M68 threaded connection standard. By replacing slip-fit adapters with a direct screw-on interface, this 40mm tube eliminates the potential for tilt and flexure that can ruin long-exposure images or spectroscopic analysis. It is an essential component for achieving precise, repeatable back focus with heavy cameras, telecentric systems, or solar H-alpha setups.

    The M68 Threaded System: A Zero-Flexure Foundation

    For professional-level astrophotography, mechanical rigidity is non-negotiable. Standard 2" compression rings can allow heavy accessories to tilt, introducing optical aberrations that are invisible visually but destructive to sensor data. The Baader M68 system, based on the standard used in large Zeiss instruments, solves this by creating a continuous, threaded optical train from the focuser to the camera sensor.

    This direct, screwed-in connection ensures perfect axial alignment under heavy loads. Whether you are using a planetary camera with a long telecentric amplifier or a solar telescope with an H-alpha filter, the M68 system prevents any component from sagging, preserving the integrity of your optical alignment throughout an imaging session.

    The 40mm Extension: Achieving Critical Spacing in Your M68 Train

    This extension tube provides exactly 40mm of rigid spacing, a critical function for dialing in the correct distance between a field flattener and a sensor or positioning a Barlow in the optical path. Unlike variable-length extenders, its fixed length is absolute and repeatable, ensuring your setup is identical every time you assemble it.

    As part of the modular Baader M68 Tele-Compendium system, this 40mm tube can be combined with other M68 extensions to achieve any required back focus distance. The interior is carefully blackened to absorb stray light, protecting image contrast and preventing internal reflections from reaching the sensor.

  • Why use a Baader M68 Extension Tube instead of a standard 2" barrel extender?

    A standard 2" extender relies on a slip-fit connection secured by set screws or a compression ring. This can introduce tilt and flexure, especially with heavy cameras or accessories. The Baader M68 Extension Tube threads directly into your optical train, creating a single rigid assembly that guarantees perfect alignment and eliminates sag.

    What is the primary application for the 40mm M68 Extension Tube?

    The 40mm M68 tube is used to achieve precise back focus spacing in a threaded imaging train. It's ideal for placing a camera sensor at the exact distance required by a field flattener, reducer, or coma corrector. It is also used to properly position components like a telecentric system for high-magnification planetary imaging or an H-alpha etalon for solar observation.

    Can I stack multiple Baader M68 extension tubes?

    Yes. The Baader M68 system is designed to be modular. You can thread multiple M68 extension tubes of different lengths together to achieve the precise, custom spacing required by your specific optical setup, all while maintaining a rigid, flexure-free connection.

    How does the Baader M68 extension tube connect to my telescope and camera?

    This tube connects to other components that have a matching M68 thread. This typically involves an M68-threaded focuser drawtube on the telescope side and M68 adapters for your specific camera, filter wheel, or off-axis guider on the other. It is a component within a larger system designed for maximum stability.

    Will the 40mm M68 tube help when imaging Jupiter with a telecentric system?

    Absolutely. Telecentric systems require precise spacing and are often long, creating significant leverage. Using the 40mm M68 tube as part of your imaging train ensures the telecentric and camera are held perfectly on-axis with the telescope, preventing tilt that would degrade the high-resolution view of Jupiter's cloud bands.

    Is the inside of the Baader M68 Extension Tube blackened?

    Yes. The interior of the tube is carefully blackened to absorb off-axis stray light. This prevents internal reflections from reducing contrast or creating artifacts on your final image, which is essential for both deep-sky and planetary astrophotography.

  • Extension Length 40mm
    Telescope Side Connection M68 x 1mm Female Thread
    Camera Side Connection M68 x 1mm Male Thread
    System Compatibility Baader M68 / Tele-Compendium System
    Net weight (kg) 0.07
    Compatible Brands Baader Planetarium, Zeiss
    Inner Diameter / Clear Aperture (mm) 62
    Outer Diameter 76
    Usage serves as additional focus distance for eyepiece projection or FFC
    Inner Connection (eyepiece/-camera-sided) M68 x 1
    Outer Connection (lens sided) M68 x 1

    • Baader M68 Extension Tube - 40mm

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  • Baader Planetarium Warranty