Variable power finder

Abstract

Abstract PURPOSE:To easily obtain a specific variable power rate while maintaining the image forming performance of finder images before and after valiable power excellently by extending a positive lens as an objective and mounting an auxiliary lens which has negative refracting power on the optical axis of the objective on its image plane side. CONSTITUTION:A finder image is formed by the objective nearby a visual field frame M through protection glass 1 and a field lens 3. This finder image is inverted upside down and horizontally by a Porro prism 4 and then observed through an ocular 5. For variation in finder power, the objective 2 is extended to an object side as shown by an arrow and the auxiliary lens 7 with negative refracting power is mounted on the optical axis of the objective on the image plane side. Consequently, specific finder power is easily obtained and optical performance before and after the power variation is maintained excellently.

Inventors

• 👤 Yasuyuki Yamada
• 👤 康幸 山田
• 👤 Yasuhisa Sato
• 👤 泰久 佐藤
• 👤 Hiroki Nakayama
• 👤 博喜 中山
• 👤 Koji Oizumi
• 👤 大泉　浩二

Bibliographic Details