Lens assembly which zooms by combined movement of plural barrels

摘要

A lens assembly is disclosed in which the amount of movement of at least one lens unit is achieved by combining the amounts of relative movement of at least two barrels. A linear advancement barrel advances straight ahead relative to a fixed barrel. A first lens unit moves together with the linear advancement barrel. A second lens unit is located in front of the first lens unit along the optical axis. A third lens unit is located behind the first lens unit along the optical axis. A cam ring moves together with the linear advancement barrel along the optical axis and rotates around the optical axis. The cam ring has first and second cams that move the second lens unit and the third lens unit by amounts of movement relative to the linear advancement barrel.