The M81 → M68 (female) adapter with stop ring for ESATTO 3" / ARCO 3" (PrimaLuceLab, SKU: PL3600262 ) enables the connection of accessories with an M68 × 1 male thread to the ESATTO 3" focuser or ARCO 3" rotator, which have an M81 × 1 front thread. The integrated stop ring allows you to precisely set the adapter's screw-in depth and lock it in the selected position, making it easier to maintain the correct back-focus and orientation of the connected device.

Key Features

• thread conversion: input M81 × 1 (ESATTO 3" / ARCO 3") → output M68 × 1 (female)
• stop ring – precise position adjustment and secure adapter lock
• optical thickness of only 7 mm – minimal impact on the back-focus budget
• full internal diameter 68 mm – no vignetting for full frame matrices
• CNC milled body made of 6061-T6 aluminum, hard black anodized – lightweight, stiff and corrosion resistant
• blackened and grooved interior – effective reduction of reflections, better contrast

Set components

• M81 → M68 adapter with stop ring
• Allen screw locking the ring

Technical parameters

• input thread: M81 × 1 (female)
• output thread: M68 × 1 (female)
• optical length: 7 mm
• Inner diameter: 68 mm
• material: aluminum 6061-T6, black anodized
• compatibility: ESATTO 3" lift, ARCO 3" rotator, accessories with M68 × 1 thread
• EAN: 8059020773274
• manufacturer: PrimaLuceLab – Italy

PL3600262 is a practical accessory when you want to connect the wide ESATTO 3" focuser or ARCO 3" rotator with correctors, reducers or other devices in the M68 standard, while maintaining full back-focus adjustment and a rigid, axial optical connection.