The invention provides a
zoom lens
system that is reduced in terms of both size and cost. The
zoom lens
system comprises a first positive lens group G1, a second negative lens group G2, a stop S, a third positive lens group G3 and a fourth positive lens group G4. During zooming from a wide-angle end to a telephoto end of the
system, while the first lens group G1 remains fixed, the second lens group G2 moves from an object side to an
image plane side of the system, the third lens group G3 moves from the
image plane side to the object side, and the fourth lens group G4 moves to keep an
image plane at a constant position. The first lens group G1 is made up of a negative
meniscus lens convex on an object side and a double-convex lens, the second lens group G2 is made up of a double-concave lens and a positive
meniscus lens convex on an object side thereof, with an aspherical surface being used for a surface of the positive
meniscus lens that is located on an image side thereof, the third lens group G3 is made up of a double-convex lens and a negative meniscus lens convex on an object side thereof, with an aspherical surface being used for a surface of the double-convex lens that is located on an object side thereof, and the fourth lens group G4 is made up of one double-convex lens.