Patent ID: 7742236

Claim:
A zoom lens comprising, in order from an object side: a first lens group having a negative power; a second lens group having a positive power; and a third lens group having a positive power, wherein at least the first lens group and the second lens group are movable during a change from a wide-angle end state in which a focal length becomes shortest to a telephoto end state in which the focal length becomes longest; the first lens group is constructed of a glass lens and a plastic lens, the glass lens being positioned on the object side and having a negative power, the plastic lens being positioned on an image side and having a positive power; the second lens group includes a single plastic lens having a negative power; the third lens group includes at least one plastic lens having a positive power; and the following conditional expressions (1), (2), (3), (4), (5), and (6) are satisfied: α>2.5; (1) lw /(α· Y )<4.5; (2) |φ P 1/φ1|≦0.55; (3) |φ P 2/φ2|≦0.3; (4) |φ P 1/φ t|< 0.7; and (5) |φ P 2/φ t|< 0.4, (6) where α is a zoom ratio (=focal length of a total system at a telephoto end/focal length of the total system at a wide-angle end); φ 1 is a power of the first lens group; φP 1 is a power of the plastic lens having a positive power in the first lens group; φ 2 is a power of the second lens group; φP 2 is a power of the plastic lens having a negative power in the second lens group; φt is a power at the telephoto end of the total system; lw is a total optical length at the wide-angle end; and Y is a maximum image height.