1. A zoom lens having a telephoto end and a wide angle end, and comprising in order from the object side a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group,wherein the following conditional expression (2) is satisfied:

0.7965?f1/?(fw×fT)?1.3 (2)

where fw is a focal length of the zoom lens taking a wide-angle position, fT is a focal length of the zoom lens taking a telephoto position, and f1 is a focal length of the first lens group,

wherein the first lens group comprises at least one lens piece that satisfies the following conditional expression (3):

0.018??PgF (3)

where PgF is the partial dispersion for glass for the respective wavelengths 435.8 nm, 486.1 nm, and 656.3 nm of spectral lines g, F, and C, given by the following expression (3):

PgF=(ng?nF)/(nF?nC),

where ng, nF, and nC are the refractive indices for the respective wavelengths 435.8 nm, and 486.1 nm, and 656.3 nm of spectral lines g, F, and C, and

?PgF is a deviation from a straight line defined by a first point having as its x, y coordinates the Abbe constant on the d-line ?d=60.49 and the partial dispersion PgF=0.5393 for a glass type C7 and a second point having as its x, y coordinates the Abbe constant on the d-line ?d=36.30 and the partial dispersion PgF=0.5829 for a glass type F2, where the Abbe constant on the d-line ?d is given by the following expression:

?d=(nd?1)/(nF?nC),

where nd is the refractive index for the wavelength 589.6 nm of spectral line d,

wherein the following conditional expression (4) is satisfied:

0.60?Lt/fT?0.75 (4)

where Lt is an entire length of the optical system of the zoom lens taking a telephoto position, and fT is a focal length of the same of the zoom lens at the telephoto position,

wherein the second lens group is held in a fixed position while all the other lens groups are displaced when zooming from a wide-angle position to a telephoto position to vary magnification,

wherein a surface closest to the object side of the third lens group is convex toward the object side,

wherein the third lens group is an immediately adjacent lens group to the fourth lens group, and

wherein during zooming from a wide-angle end to a telephoto end, the third lens group is axially moved toward the object side.