All Schneider's Compact, C-mount lenses have adjustable focus capability. When you receive your new Compact, C-mount lens, it will look something like this:
Middle adjustment of lens

The lens is actually composed of two parts - the black lens body and the silver focus-locking collar.

Note that the focus-locking collar contains a 2mm hex head screw. Once this hex head screw is loosened (about three revolutions), the focus-locking collar can be screwed onto the lens body...

...or unscrewed from it. This takes a while to do this because it is a fine pitch (23mm x 0.50) thread.

HOW TO MOUNT A LENS ON A CAMERA
- Use a 2-mm Allen Key to make sure the focus-locking collar screw is tight.
- Screw the lens onto your camera and make sure the fit is tight. (Note: If the focus-locking screw ends up in an inaccessible position, you may need to remove the lens from your camera, loosen the locking screw, spin the locking collar about 45 degrees, tighten the locking screw again, and reinstall the lens on your camera.)
- Use a 2-mm Allen Key to loosen the focus-locking collar screw.
- Rotate the focus-locking collar to a position that puts the focus-locking screw in a convenient orientation.
- Rotate the lens body to bring the image into focus.
- Use a 2-mm Allen Key to re-tighten the focus-locking collar screw.