Plastic lens.

摘要

A plastic lens includes a lens body (13) having an effective optical diameter and which is mounted in a lens mount (11) by means of a retaining ring (12) which is threaded in the mount. A portion (14) is formed outside the lens body (13) and is thinner than the minimum thickness of the lens body. An end portion (15) is formed outside from and thicker than the thin portion (14) and is adapted to secure the lens between the lens mount and the retaining ring. The thin portion (14) absorbs heat stress caused by a difference in the linear elongation co-efficient as between the plastic lens and the aluminium lens mount.