M81 × 1 extension tube 65 mm for ESATTO 3" (PrimaLuceLab, SKU: PL3600284 ) extends the optical path of the ESATTO 3" focuser by exactly 65 mm. The tube has an external and internal M81 × 1 thread, so it can be screwed directly between the focuser and any accessory (ARCO 3 rotator, corrector, filter wheel, camera) without losing axiality and mechanical stiffness.

Key Features

• precise optical length of 65 mm – easy adjustment of the back-focus budget
• Threads: M81 × 1 male (extractor side) / M81 × 1 female (accessory side)
• full internal diameter 76 mm – no vignetting for full frame matrices
• CNC milled body made of 6061-T6 aluminum, hard anodized - lightweight and corrosion resistant
• blackened and grooved interior – effective reduction of reflections, better contrast

Set components

• spacer sleeve 65 mm M81 × 1

Technical parameters

• input thread: M81 × 1 (female)
• output thread: M81 × 1 (male)
• optical length: 65 mm
• Inner diameter: 76 mm
• material: aluminum 6061-T6, anodized
• Compatibility: ESATTO 3" extractor and accessories with M81 × 1 thread
• EAN: 8059020773410
• manufacturer: PrimaLuceLab – Italy

PL3600284 is a simple and precise solution when you need to increase the back-focus by 65 mm in astrophotography setups with an ESATTO 3" focuser, while maintaining full aperture and mechanical stability of the entire system.