ZOOM LENS

• Main Author: HASHIMOTO AKIHIKO
• Format: Patent
• Language: English
• Published: 15.03.1983
• Subjects: ACCESSORIES THEREFOR; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES; APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM; CINEMATOGRAPHY; ELECTROGRAPHY; HOLOGRAPHY; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHOTOGRAPHY; PHYSICS

PURPOSE:To shorten the lens barrel length of a two-group type zoom lens system and to obtain sufficiently long engagement length by fitting a lens barrel for holding one lens group around the external circumference of a fixed lens barrel, and also fitting the other lens barrel for holding the other lens group in the internal circumference. CONSTITUTION:The 1st fixed barrel 1 to be mounted on a mount M has upper and lower openings 2 and 3, and is provided with a rear-group lens 4 and a front-group lens barrel 5 at the internal and external circumferences respectively in such a way that they move forth and back in the optical axis directions. The lens barrels 4 and 5 are provided with a rear-group lens 6 and a front-group lens 7 respectively. Then, the lens barrels 4 and 5 have spiral grooves 8 and 9 cut in the external circumferences respectively. The 2nd fixed lens barrel 10 is provided around the front-group lens barrel 5 and also has upper and lower openings 11 and 12 while blocked by a zoom ring 13. A working plate 13a is provided in the opening 3 and its tip pin 13b is engaged with the groove 8. A focusing ring 18 moves along a hole 14, and a coupled ring 15 is rotated by the zoom ring 13.