Refractors without adjustment screws and where the lens cell is attached to the tube with screws can be adjusted by tilting the lens cell relative to the tube.

To do this, slightly loosen the three screws on the lens cell, allowing the lens cell to be tilted slightly. Observe a star, such as Polaris (we use an artificial star), at high magnification of 100x or more. When the star image is concentric, retighten the screws, and the adjustment remains.

If the lenses show coma, they are too tight in the lens mount.

The front ring can be loosened slightly, which will reduce the pressure on the lens.

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