A lens system includes a plurality of lens elements arranged from an object side to an image plane side, and a diaphragm arranged between the plurality of lens elements. The plurality of lens elements include a plurality of freeform lenses each having a freeform surface that is asymmetrical with respect to a first direction and a second direction which cross with each other. At least one freeform lens is placed on the image plane side of the diaphragm. With a lens thickness T1 in the first direction at a maximum height of an axial ray and a lens thickness T2 in the second direction at the maximum height of the axial ray, at least one freeform lens satisfying 0.3