Variable power finder optical system

Abstract

Abstract PURPOSE:To vary the power of a finder optical system through inexpensive constitution with high precision by varying the focal length of the liquid crystal lens in the finder optical system associatively with the power variation of a photographic lens system. CONSTITUTION:When the photographic lens system is moved to the telephoto side, a switch 12 is turned on and the voltage of a battery 13 is converted by a DC/AC converter 11 into an AC voltage, which is applied to liquid crystal 9 through transparent electrodes 10a and 10b. Consequently, liquid crystal molecules are oriented to the transparent electrodes 10a and 10b according to the voltage. Therefore, the refractive index to light incident on the liquid crystal as extraordinary light varies. For the purpose, the polarizing direction A of a polarizing plate 2a is made coincident with the orientation direction B of the liquid crystal 9 to make the extraordinary light incident on the liquid crystal lens 2a, and then the focal length of the liquid crystal lens 2b to the incident light increases to convert the power of a finder to a high-power side. At this time, the object-side negative lens 4a of an Albada system 4 is moved along the optical axis without any variation in diopter.

Inventors

• 👤 Masao Kuga
• 👤 久我　正雄
• 👤 Kiyoshi Fujii
• 👤 藤井　澄
• 👤 Kenichi Nakabashi
• 👤 中橋　憲一
• 👤 Yuji Morita
• 👤 森田　勇次

Bibliographic Details