Patent ID: 8493665

Claim:
A zoom lens comprising: 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, and a fourth lens group having a positive refractive power, which are disposed in order from an object side to an image side; and an aperture stop disposed between the second and third lens groups, wherein when changing magnification of the zoom lens from a short focal end to a long focal end, an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups increases; the first and third lens groups are moved so as to be positioned at object side positions at the long focal end relative to positions at the short focal end; the third lens group has two positive lenses including a first positive lens L_p 1 and a second positive lens L_p 2 which are disposed in order from an object side; and in a case where a partial dispersion ratio P g,F is defined by the following equation: P g,F =( n g −n F )/( n F −n C ) where n g , n F , and n c are refractive indices of a positive lens for g, F, and C lines, respectively, the following conditions are satisfied: 3.1 <p 1 — n d +p 2 — n d <3.4 (1) 60<p1_ν d <80 (2) 60<p2_ν d <80 (3) 0.008 <p 1 — P g,F −(−0.001802 ×p 1_ν d +0.6483)<0.050 (4) 0.008 <p 2 — P g,F −(−0.001802 ×p 2_ν d +0.6483)<0.050 (5), where p 1 _n d is a refractive index of the first positive lens L_p 1 , p 2 _n d is a refractive index of the second positive lens L_p 2 , p 1 _ν d is an Abbe number of the first positive lens L_p 1 , p 2 _ν d is an Abbe number of the second positive lens L_p 2 , p 1 _P g,F is a partial dispersion ratio of the first positive lens L_p 1 , and p 2 _P g,F is a partial dispersion ratio of the second positive lens L_p 2 .