| 摘要 |
PROBLEM TO BE SOLVED: To provide an inner focus type zoom lens which is capable of high- precision automatic focusing and manual focusing. SOLUTION: This lens system has movement tracks g1 -g4 of focusing lens groups G1-G4 by the composition of a moving cam for focusing and a moving cam for power variation correction. In this case, when the sensitivity of image formation point movement to the movement of the focusing lens groups G1-G4 along the optical axis is larger in a short-distance focusing state than in an infinite-distance focusing state, the ratio of the quantity of focusing rotation from the infinite distance to the short distance to the quantity of power variation rotation by the moving cam for focusing from wide-angle focusing to telephoto focusing is set within a specific range so that the sensitivity of the image formation point movement to the movement of the focusing lens group in a rotating direction meet specific conditions. |
