Imaging system

The invention relates to an imaging system, which comprises a front lens group and a rear lens group, wherein the front lens group and the rear lens group are arranged in turn along an optical axis from the object side to the image side, the rear lens group is a fixed lens group with the position being fixed, the front lens group is a focusing lens group which can move along the optical axis; thefront lens group has positive focal power, and the rear lens group has positive focal power or negative focal power; and the focal length f1 of the front lens group and the focal length f2 of the rearlens group meet a relational expression that f1/f2 is greater than -0.04 and less than 0.02. The imaging system of the invention adopts the dual-lens-group structure combined by the front lens groupand the rear lens group, a sufficient rear focus and a small image-side main light incident angle can be easily ensured because the rear lens group is a fixed lens group, the imaging quality and the color restoration of the fro