Adapter to fit 40-mm diameter lens into 2 inch mounts

Motivation: some lenses are available only in 40 mm diameter, which is quite uncommon. However, most optomechanical mounts accept 1 or 2-inch diameter optics.

Solution: this is a simple adapter for 40-mm diameter lens to fit into 2-inch optomechanical mounts.

The ring is cut so that lens can be easily inserted or removed from the ring.

For best results, apply a 1-2 drops of glue or wax between lens edge and adapter, so the lens cannot slip out.