| 摘要 |
PURPOSE:To satisfy specifications of a zooming ratio of three times by which a focal distance and brightness extend from 35mm. F3.5 at a wide angle side to 105mm. F4.5 at a telephoto side, by constituting 15 pieces of single lenses of four groups, and satisfying various conditions of specified expressions. CONSTITUTION:G1 is negative meniscus lens whose concave face is turned to an image side, G2 is a positive lens, G3 consists of a positive mensiscus lens whose convex face is turned to an object side, G4 is a negative lens whose concave face is turned to the image side, G5 is a positive meniscus lens whose convex face is turned to the iage side, G6 is a negative lens, G7 is a positive meniscus lens whose convex face is turned to the object side, G6 and G7 are cemented composite negative lenses, and G8 consists of a positive meniscus lens whose convex face is turned to the object side. G9 and G10 are positive lenses, G11 consists of a negative lens whose concave face is turned to the object side, G12 and G13 are positive lenses, G14 is a negative lens, and G15 is constituted of a positive lens whose convex face is turned to the image side. Variable magnification and focusing can be executed by a relation movement of the first, the third and the fourth lens groups, and a single movement of the first lens group, respectively, also various conditions of a specified expression are satisfied, and a zooming ratio of three times is satisfied in a range where a focal distance and brightness extend from 35mm. F3.5 at a wide angle side to 105mm. F4.5 at a telephote side. |
