| 摘要 |
A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power arranged to move during a variation of magnification, a third lens unit arranged to move during a variation of magnification, and a fourth lens unit of positive refractive power, the first lens unit including a first lens subunit of negative refractive power, a second lens subunit of positive refractive power arranged to move during focusing, and a third lens subunit of positive refractive power, wherein the zoom lens satisfies the following conditions:where deltabeta1 is the ratio of a lateral magnification of the first lens unit with respect to a standard-distance object obtained when the second lens subunit is located at such a position as to focus on a minimum distance to a lateral magnification of the first lens unit with respect to the standard-distance object obtained when the second lens subunit is located at such a position as to focus on an infinite distance, deltabeta24 is the ratio of a lateral magnification of a lens system composed of the second lens unit to the fourth lens unit with respect to the standard-distance object obtained when the second lens subunit is located at such a position as to focus on the minimum distance to a lateral magnification of the lens system composed of the second lens unit to the fourth lens unit with respect to the standard-distance object obtained when the second lens subunit is located at such a position as to focus on the infinite distance, f11 is the focal length of the first lens subunit, and f12 is the focal length of the second lens subunit.
|
