Patent ID: 8116010

Claim:
A projection variable focus lens comprising of: seven lenses including first and second lenses that are provided closest to a magnification side and have a negative composite refractive power, a third lens having a positive refractive power, a fifth lens having a negative refractive power, a sixth lens having a positive refractive power, and a seventh lens having a positive refractive power, wherein the first to seventh lenses are provided in this order from the magnification side, a reduction side of a lens system is telecentric, the seven lenses are classified into three or more lens groups, three or less of the three or more lens groups are movable to change a focal length, when the focal length varies from a wide angle end to a telephoto end, the third lens is moved from the reduction side to the magnification side along an optical axis, the seven lenses include a fourth lens from the magnification side that has a positive refractive power and includes a convex surface facing the reduction side, and the projection variable focus lens satisfies the following conditional expression: −2.2 <fl 2 /fw<− 0.5 where fw indicates the focal length of the entire system at the wide angle end, and f12 indicates a composite focal length of the first lens and the second lens.