Baader M68 Extension Tube – 40 mm

Baader M68 Extension Tube – 40 mm

Description
The Baader Planetarium M68 – 40 mm extension tube is designed for demanding optical setups where mechanical precision and rigidity are essential. In astrophotography or spectroscopy, any flexure or tilt in the optical train can degrade sharpness, cause misalignment, or reduce the quality of recorded data.

This issue is even more critical when using long, heavy accessories such as telecentric systems or the Fluorite Flatfield Converter (FFC), which exert significant mechanical leverage on the focuser. Slip-fit connections, even with high-quality brass compression rings, may not always guarantee perfect alignment and can allow slight tilting.

The use of an M68 x 1 thread, derived from the standard used on high-end Zeiss telescopes, ensures a wide and secure screw coupling that eliminates play and tilt, while maintaining perfect concentricity. Precision-machined from high-grade aluminium, this extension tube provides a generous contact surface for optimal holding strength and rigid mechanical coupling.

With a 40 mm optical length, it is ideal for:

• Precisely adjusting backfocus

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

• Using a telecentric system with H-alpha filters for solar observation

• Ensuring full compatibility with M68 and Zeiss accessories

The tube’s interior is carefully blackened to suppress stray light and maintain image contrast. Precision threading ensures smooth, secure assembly without binding, preserving perfect optical axis alignment.

It can be used alone or combined with other M68 extensions to achieve the required spacing. 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: 2458204

• EAN code: 4047825009951

• Adapter family: M68 system

• Optical length: 40 mm

• Telescope-side external thread: M68 x 1

• Accessory-side internal thread: M68 x 1

• Clear aperture: 62 mm

• Outer diameter: 76 mm

• Weight: 0.07 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