Abstract: The invention relates to a zoom lens and an imaging apparatus incorporating the same. More particularly, the invention is concerned with a zoom lens that is downsized for use with imaging apparatus inclusive of video cameras and digital cameras. The zoom lens comprises a positive first group G1, a negative lens group G2, a positive third group G3, a positive fourth group G4 and an aperture stop S. At least the first group G1 and the second group G2 move for zooming from the wide-angle end to the telephoto end. The first group G1, the third group G3 and the aperture stop S are positioned more on the object side in a state of the telephoto end than in a state of the wide-angle end. The spacing sandwiched between the first group G1 and the second group G2 grows wide, the spacing sandwiched between the second group G2 and the third group G3 becomes narrows, and the spacing sandwiched between the third group G3 and the fourth lens group G4 grows wide.

Abstract: A zoom optical system comprising, in order from an object side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a positive refractive power, a space between the lens units being changed to thereby perform zooming and focusing, wherein the first lens unit is constituted of a negative lens.

Abstract: The invention relates to a less costly zoom lens that can offer a sensible tradeoff between size reductions and high zoom ratios with a well-kept image quality, and that lends itself to an electronic imaging device such as a CCD or CMOS. The zoom lens comprises a positive first lens group G1, a negative second lens group G2, a positive third lens group G3 and a positive fourth lens group G4, wherein zooming is implemented by changing the space between adjacent lens groups. The first lens group G1 comprises one positive lens, the second lens group G2 comprises two lenses, and the fourth lens group G4 comprises one positive lens. The zoom lens satisfies condition (1) needed for making sure an ideal situation for the zoom ratio and low costs and condition (2) needed for the first lens group to comprise a minimum one lens and to hold back chromatic aberration of magnification as much as possible.

Abstract: A zoom lens system has, in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, an aperture stop, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power; during magnification change, the first lens unit, the second lens unit, the third lens unit, the fourth lens unit and the aperture stop move; the first lens unit includes a negative lens and a positive lens in order from the object side; the second lens unit includes a negative lens and a positive lens in order from the object side; the third lens unit includes three or less lenses including one positive lens and one negative lens; and the fourth lens unit includes one positive lens.

Abstract: A zoom optical system comprising, in order from an object side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a positive refractive power, a space between the lens units being changed to thereby perform zooming and focusing, wherein the first lens unit is constituted of a negative lens.