Lens barrel capable of axial zooming operation and with barrel window

Abstract

A zoom lens barrel capable of indicating adjusted distance and focal length is of compact construction having only those members essential for focusing and zooming. No special scale member is provided, although a focal length or zoom ratio scale extends circumferentially along the outer periphery of a cam ring which is rotated upon the zooming operation, while a distance scale extends circumferentially along an operating ring substantially at its rearward end. A stationary barrel on and in which the cam ring and the operating ring, respectively, are fitted has a window for the focal length or zoom ratio scale and an index at an external position adjacent the rearward end of the operating ring. Rotation of the ring causes helicoid threads to axially move a first lens group for focusing and the adjusted distance on the distance scale is indicated by the index. Axial movement of the operating ring axially moves the front lens group as well. This causes a pin-slot engagement to rotate the cam ring so that a second lens group is axially moved for zooming in a given spacial relationship with respect to the first lens group, and the adjusted focal length or zoom ratio on the focal length or zoom ratio scale seen through the window is indicated by the index.