Rear group adjusting video shooting high-definition zoom lens and rear group adjusting method for lens

The invention relates to a rear group adjusting video shooting high-definition zoom lens and a rear group adjusting method for the lens. The lens comprises a front fixed lens group with a positive focal length, a zoom lens group with a negative focal length, a compensating lens group with a positive or negative focal length, a diaphragm and a rear fixed lens group with a positive focal length, and the front fixed lens group, the zoom lens group, the compensating lens group, the diaphragm and the rear fixed lens group are arranged on a main optical shaft in order in light incident direction. The lens also comprises a rear adjusting lens group located between the rear fixed lens group and an image surface. The rear adjusting lens group has a positive focal length and can move back and forth between the rear fixed lens group and the image plane to adjust an image formed by an object when an object distance is changed and thus the image shown in the image plane position is clear. The zoom lens group and the compensating lens group are in linkage connection and achieve change of the lens focal length. In the method, a focal length is adjusted through the rear adjusting lens group. Better image quality can be obtained in a near distance when the provided method is compared with a front group adjusting method. During the focusing process, the caliber of the lens front group is not changed, the whole length of the lens is not changed, and the combined focal length of the lens is not changed basically.