Patent ID: 8254035

Claim:
A zoom lens comprising: a plurality of lens groups having at least first, second, third, fourth, and fifth lens groups arranged in order from an object side, wherein; the first lens group having a positive refractive power which is firmly secured when the magnification is changed, the second lens group having a negative refractive power which is shifted to the image side when the magnification is changed from the wide angle end to the telescopic end, the third lens group having a positive refractive power which is firmly secured when the magnification is changed, the fourth lens group having a positive refractive power which is shifted to the object side when the magnification is changed from the wide angle end to the telescopic end, and the fifth lens group having a negative refractive power which is firmly secured when the magnification is changed, wherein the first lens group is configured by arranging, in order from the object side, a single lens having a negative refractive power, a prism having a reflection surface to create a 90° bend in a light path, and at least one single lens having a positive refractive power, a double convex shape, and a double-aspherical surface, wherein the prism has a positive refractive power, at least one surface thereof has an aspherical surface, a object side surface thereof has a convex surface directed to the object side, and an image side surface thereof has a convex surface directed to the image side, wherein the second lens group is configured by arranging in order from the object side, a lens having a negative refractive power, a lens having a negative refractive power, a lens having a positive refractive power, and a lens having a negative refractive power, and wherein the positive lens, the negative lens and the prism constituting the first lens group satisfy one of the following conditional expressions (1) and (2): ν1 p−ν 1 n= 33.27 (1), and ν1 p−ν 1 n= 36.15 (2), where ν1p is the average value of the Abbe number, at the d line, of the prism in the first lens group and the positive lens arranged on the image side of the prism (the wavelength is equal to 587.6 nm); and ν1n is the Abbe number at the d line of the negative lens arranged at a position most near to the object side in the first lens group.