Cam structure for zoom lens barrel assembly

摘要

A cam structure for a zoom lens barrel assembly which includes a first lens group including first and second sub-lens groups, and a second lens group; and a sub-lens group switching mechanism for moving one of the first and second sub-lens groups away from the other in a short focal length photographing range, and toward the other in a long focal length photographing range. The cam structure includes a zoom cam ring having front and rear lens group cam grooves for moving the first and second lens groups toward and away from each other. The front and rear lens group cam grooves are determined according to the following equation:wherein 0<K<1;A designates the other sub-lens group position;B designates the second lens group position; andC designates an imaginary point position between positions A and B.