@studiobinder: Comment THREEMARKS and we'll send you the link. There are really three kinds of marks, and each protects something different. Actor's marks matter most: focus and exposure are set for a specific distance, so even a foot off the mark can go soft or land in the wrong light. Camera marks tell the dolly or the operator where to be, for consistent distance and framing. And furniture or prop marks tell the art department where a chair, table, or prop sits, so continuity holds from take to take and setup to setup.