| 摘要 |
PURPOSE:To shorten the time of a focusing a subject in a finder at the time of focusing operation and to speed up the focusing by setting a focus lens at a last focusing position, position of a half of an all extension quantity, or fixed- focus position and then measuring a distance again if the range can not be measured. CONSTITUTION:A power varying lens 2 consists of a single or plural lenses, i.e. 1st - 5th lenses 2a - 2e arranged movably along the optical axis 1 and a focus lens 3 is composed of the 1st lens 2a and 2nd lens 2b. Before the distance is measured again, the focus lens 3 is moved to the last focusing position, position of a half of the all extension quantity, or fixed focus position. Consequently, the subject image in the finder is prevented from becoming out of focus greatly, the subject can easily be focused on a focus area, and the time required for the focusing is shortened. |
