| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens capable of achieving a resolution corresponding to a small imaging element of 10 million to 20 million pixels while a half field angle at a short focal end is 42 degrees or more, an f-number at a short focal end is 2.0 or less, an f-number at a long focal end is about 3.0, and the number of lenses is small.SOLUTION: A zoom lens is constituted by arranging, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, and a positive fourth lens group G4. When varying power from the short focal end to the long focal end, the first lens group G1 is moved so as to be convex to an image plane side, the second lens group G2 is moved to the image plane side, the third lens group G3 is moved to the object side, and the fourth lens group G4 is moved. An aperture diaphragm AD is disposed between the second lens group G2 and the third lens group G3 and operated so as to move independently, when varying power from the short focal end to the long focal end. The first lens group G1 is constituted of negative and positive lenses and the second lens group G2 is constituted of negative, negative, negative, and positive lenses. |
