Description

OnAxisLock2 50.8mm visual back screws directly onto the M56 thread of ESATTO 2" focuser or ARCO 2" rotator and lets you connect any 50.8mm accessory with a simple manual rotation of the outer ring. Unlike traditional set-screw locking systems, OnAxisLock2 uses a double compression ring that distributes pressure evenly around the full barrel circumference: no scratches, no flexure, no off-axis tilt. The result is a perfectly centered optical axis, whether you are doing visual observation or precision astrophotography even with heavy cameras. The knurled outer ring is easy to operate even with gloves on. Optical thickness: 26mm.

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. 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.

Designed to integrate with ESATTO 2" and ARCO 2"

OnAxisLock2 screws directly onto the M56 thread of ESATTO 2" motorized focuser or ARCO 2" field rotator. No adapters, no additional components. The mechanical connection between focuser, rotator and locking device is rigid and repeatable.

For visual use and astrophotography

OnAxisLock2 is equally suited for visual and photographic use:

• Connect heavy 2" eyepieces and mirror diagonals without any wobble
• Connect DSLR or mirrorless cameras, cooled astronomy cameras or any accessory with a 2" nose screw
• Use it with filter wheels and other photographic accessories where maintaining the sensor perpendicular to the optical axis is critical

The even pressure distribution also protects your accessories: the barrel is not scratched or deformed.

Easy to use, even in the dark

The outer ring has been designed with a deeply knurled grip that allows you to lock and unlock accessories with fingertip pressure. You do not need tools. You can operate it comfortably even when wearing gloves in cold conditions, and the tactile feedback of the ring lets you confirm the lock position without looking.