Baader Planetarium M68 VariLock Extension – 15-20 mm

The M68 VariLock is designed for fine-tuning the back focus distance in an M68-threaded imaging train. It is crucial when using field flatteners or focal reducers that require a very specific distance to the sensor for optimal performance, allowing you to achieve any spacing between 15mm and 20mm.

The M68 dovetail and receptor provide two key benefits. First, it creates a secure, zero-tilt mechanical lock that prevents flexure. Second, it allows you to rotate your camera for precise framing without unthreading any components, which maintains optical alignment and prevents the connection from loosening accidentally.

Yes, absolutely. The M68 VariLock's continuous 15mm to 20mm adjustment range covers 17.5mm perfectly. You can set it to that exact distance, lock it down, and be confident your spacing is correct without needing to stack multiple fixed-length spacers.

The M68 VariLock uses the standard M68x1 thread pitch. It is designed to integrate with other components that use this common large-format thread, making it a versatile tool for building robust imaging trains with parts from various manufacturers.

After achieving focus, you can slightly loosen the VariLock's locking mechanism. This will allow you to rotate your entire camera and filter wheel assembly smoothly. You can then orient your camera sensor to perfectly frame M31's elongated disc and then re-tighten the lock, all without affecting focus or optical alignment.

No. The M68 dovetail and receptor system is specifically engineered to provide a rigid, secure connection that resists flexure, even with heavy cameras or filter wheels. This is a significant improvement over simple friction-fit or set-screw extension tubes.