M117 to M117 Extension Tube – 25mm

The Dark Clear Skies M117 to M117 25mm Extension Tube is a precision-machined spacer designed for fine back focus adjustment in large-format astrophotography imaging systems.

Featuring M117×1 male threads on both ends, this extension tube is ideal for making smaller spacing corrections when pairing large reducers, flatteners, filter systems, and cameras. The 25mm optical length allows accurate tuning of optical spacing while maintaining a rigid and well-aligned imaging train.

Manufactured from high-quality aluminium alloy and internally blackened, the tube minimises stray reflections and preserves image contrast in demanding deep-sky imaging setups.

Key Features

• M117×1 male to M117×1 male threads
• 25mm extension length
• Ideal for fine back focus adjustment
• Precision-machined aluminium construction
• Internally blackened to reduce reflections

Specifications

• Thread Type: M117 × 1 (male to male)
• Extension Length: 25 mm
• Material: Aluminium alloy
• Application: Astrophotography back focus spacing
• Finish: Black anodised

Typical Applications

• Fine spacing adjustment for reducers and flatteners
• Large-format camera imaging trains
• Observatory-class telescope systems
• Rigid optical train extension