| 摘要 |
PURPOSE:To correct satisfactorily an aberration variation of a small-sized zoom lens having a wide variable power area including a wide view angle by moving the first lens group to an object side, and also moving as one body the second and the third lens groups to an image side so as to be focused on a short distance object. CONSTITUTION:A titled zoom lens is constituted of four groups consisting of the first lens group G1 of a positive refractive power, the second lens group G2 of a negative refractive power, the third lens group G3 of a positive refractive power, and the fourth lens group G4 of a positive refractive power, in order from an object side, and an almost afocal system is formed by the first, the second and the third lens groups. In this state, when focusing this lens to an object of a short distance, it is constituted so that the first lens group G1 is moved to the object side along the optical axis against an image surface I , and also the second lens group G2 and the third lens group G3 are moved as one body to the image side along the optical axis. In this way, a short distance variation of a curvature of image is reduced remarkably, and also a structure of a lens barrel is simplified. |
