The CS & C ring does not fit with the camera or lens it came with.
- There should be a back focus ring in that front panel of the camera as shown in Reference Diagram #1. It's held up by two set screws on the opposite end. If you tried fitting the lens without the CS ring, It may have gotten stuck onto the lens. If the set screws were not very tight it would come out with the lens.
- If the back focus ring is not present on the camera or the lens, please refer to Reference Diagram #2 and email what part missing to email@example.com