The lens MC Zenitar-M 2.8/16mm accepts rear filters by default.

If you want to use front filters, you need such filter adapter.

It has 62mm inner diameter to match outer diameter of the lens housing, and female M77x0.75 thread to accept filters.

The lens is fish-eye, so it is necessary to place your filter as close to the front glass as possible. Recommended installation procedure is following:

1. Loose three set screws on the step ring.

2. Screw your filter into the step ring till stop.

3. Place the step ring onto the lens and slide it carefully till stop. Caution is necessary since front ring of the lens barrel will touch the filter glass. DON'T ROTATE filter or step ring after you placed it onto the lens, or you may scratch filter glass.

4. Tighten three set screws of the step ring gently.

Remove in reverse sequence - release screws and pull the step ring off the lens first, and unscrew filter out of the step ring then.