Baader Bague d’extension M68 – 20 mm

Baader M68 Extension Tube – 20 mm

Description
The Baader Planetarium M68 – 20 mm extension tube is a key component for professional optical setups requiring precise backfocus adjustment and absolute mechanical rigidity. In astrophotography or spectroscopy, even the slightest flexure between the telescope and camera can seriously degrade image quality, cause apparent misalignment, or introduce unwanted optical aberrations.

This issue becomes more pronounced when using long, heavy accessories such as telecentric systems or the Fluorite Flatfield Converter (FFC), which apply significant leverage to the focuser. Slip-fit connections, even with brass compression rings, are not always sufficient to eliminate such micro-movements.

The M68 x 1 thread, widely used in high-end instruments like Zeiss telescopes, ensures a large, secure screw connection that eliminates tilt and guarantees perfect stability. Precision-machined from high-grade aluminium, this extension tube delivers impeccable concentricity and a wide contact surface for optimal optical alignment.

With its 20 mm optical length, this extension is ideal for:

• Fine-tuning backfocus in imaging or spectroscopy configurations

• Achieving optimal working distance when using an FFC for high-resolution planetary imaging

• Operating telecentric systems with H-alpha filters for solar observation

• Ensuring mechanical and optical compatibility with M68 and Zeiss accessories

The interior surface is carefully blackened to prevent internal reflections and maintain image contrast, even under bright-light conditions. Precision threading ensures smooth, secure assembly without binding, while maintaining perfect optical axis alignment.

This extension tube can be used on its own or combined with other M68 extensions to achieve the required length. It integrates seamlessly into Baader’s modular M68 system, with optional adapters available for other standards (Astro Physics 2.7", M60 Vixen, M56 Synta, etc.).

Technical specifications

• Manufacturer: Baader Planetarium

• SKU: 2458202

• EAN code: 4047825009968

• Adapter family: M68 system

• Optical length: 20 mm

• Telescope-side external thread: M68 x 1

• Accessory-side internal thread: M68 x 1

• Clear aperture: 62 mm

• Outer diameter: 76 mm

• Weight: 0.05 kg

• Material: precision-machined aluminium

• Internal finish: matte black anti-reflective coating

• Usage: extension for eyepiece projection or FFC

• Compatibility: Baader M68 and Zeiss systems