M54 Male to M42 Male Adapter

The threading on the adapter is precise and clean, locking into my filter wheel without any wobble. It’s incredibly thin at 2mm, so I didn’t lose any back focus for my imaging train.

I was worried about back focus issues with my setup, but this adapter's 2mm thickness fits perfectly between my reducer and camera. The M54 to M42 threads engaged smoothly with no wobble.

The threading is so precise on this adapter, it screws onto my flattener with zero play. The 2mm thickness is just right for keeping the back focus where I need it.