| 摘要 |
<p>PURPOSE:To obtain the lens with large power variation which is not large in front-lens diameter and short in overall length, and has excellent image formation characteristics and reduces the quantity of movement of a group for focus correction even when the power variation range is extended to the wide-angle side. CONSTITUTION:This lens consists of a 1st positive group G1, a 2nd negative group G2 which is movable at the time of power variation, a 3rd group G3 which is movable toward an object side along a convex track when the power is varied from the wide-angle end to the telephoto end, a 4th positive group G4 which is so movable as to correct focus movement at the time of power variation and due to a shift in object point position, and a 5th group G5 which is always fixed; and an aperture stop is arranged between the most image side surface of the 2nd group G2 and the most object-side surface of the 4th group G4 and (1) 1.0<beta5<2.0 holds, where beta5 is the lateral power of the 5th group G5.</p> |
