M90 to M90 Extension Tube – 25mm

The Dark Clear Skies M90 to M90 25mm Extension Tube is a precision-machined spacer designed for fine back focus adjustment in astrophotography imaging trains that use large-diameter M90 threading.

Featuring M90×1 male threads on both ends, this extension tube is ideal for making smaller spacing corrections when pairing reducers, flatteners, filter systems, and cameras that require accurate optical spacing. The 25mm extension length allows precise tuning 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 contrast in demanding deep-sky imaging configurations.

Key Features

• M90×1 male to M90×1 male threads
• 25mm extension length
• Ideal for fine back focus adjustment
• Precision-machined aluminium construction
• Internally blackened to reduce reflections

Specifications

• Thread Type: M90 × 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
• Advanced astrophotography setups
• Rigid optical train extension