Focus device for front lens fixed zoom lens

Abstract

Abstract PURPOSE:To prevent photographic power from varying abruptly by photographing a short-distance point temporarily in the middle photography and returning a focusing lens and a power varying lens to positions which are calculated by a detector and stored when the normal photography is restarted. CONSTITUTION:The front lens fixed zoom lens system 14 consists of a fixed front lens 15, the power varying lens 2, and the focusing lens 8. When a power source is turned on, a CPU 24 drives motors 19 and 18 through motor driving circuits 20 and 21 to move the lenses 2 and 8 to their origin positions and switches (SW) 22 and 23 are turned on. Zooming is indicated 1 to a dsired value with SW 16 and the focus is indicated 7 to, for example, 5m to start photography. When focusing 7 on a short-distance point is obtained in the middle, the CPU 24 detects the current position of the power varying lens 2 and stores it, and the lens is moved to a short-focus side. Then, when 5m focusing is set again, the CPU 24 returns the power varying lens 2 to the stored position. Thus, abrupt variation in photographic power is prevented.

Inventors

• 👤 Hiroshi Makino
• 👤 博 牧野
• 👤 Tadaharu Kihara
• 👤 木原　忠晴
• 👤 Akira Takashima
• 👤 明 高嶋

Bibliographic Details