| 摘要 |
<p>PURPOSE:To provide the ultra-compact lens of telephoto ratio about 1.0, angle of view 60 deg. or more abd F-number 3.5 by providing the 1st group of a positive meniscus lens whose convex face is directed to the object side, the biconcave 2nd group, the biconvex 3rd group and the 4th group of a negative meniscus lens in such a manner as to satisfy the specific conditions. CONSTITUTION:The lens is so made as to satisfy the conditions of formula I among the focal length f of the entire system, the combined focal length f123 of the 1st, 2nd and 3rd group lenses, the focal length f4 of the 4th group lens, the wall thickness d3 of the 3rd group lens and the air spacing d6 between the 3rd group and 4th group lenses. Such constitution yields the ultra-compact photographic lens of telephoto ratio about 1.0, angle of view 60 deg. or more and F-number 3.5.</p> |
