PRIMA LUCE LAB OnAxisLock2 2" FOR ESATTO / ARCO 2"

The PrimaLuceLab OnAxisLock2 2" for ESATTO & ARCO 2" is a double compression ring eyepiece holder which perfectly centres 2" eyepieces and accessories with no flexure, no scratches and no off-axis tilt.

Whether you are using eyepieces and diagonals for visual observation or precision astrophotography with heavy cameras, the OnAxisLock2 ensures a perfectly centred optical axis. Simply attach the OnAxisLock2 to the M56 x 1 threads as found on the PrimaLuceLab Esatto 2" electronic focuser or Arco 2" robotic rotator, then rotate the outer ring clockwise to secure your gear in place.

Why a locking ring matters

When you insert a heavy camera, a filter wheel, or a large mirror diagonal into a focuser, the weakest point in the optical chain is often the accessory clamp. A traditional set screw applies all clamping force to a single contact point on the barrel. Under load, this causes micro-flexures that shift the focal plane and tilt the sensor relative to the optical axis. It also leaves pressure marks and scratches on expensive accessories.

The OnAxisLock2 solves this with a double compression ring mechanism. A single manual rotation of the outer ring simultaneously tightens two internal rings that grip the inserted barrel with uniform, 360° pressure. The accessory is held firmly against any tilting movement, perfectly centered on the optical axis of the telescope.

Note: Unlike the 1.25" version, the OnAxisLock2 2" is designed specifically to fit the M56 x 1 threads of the Esatto 2" and Arco 2".

Specifications