Patent ID: 8836822

Claim:
A zoom lens system which is used in a spectrum region including visible light and which includes a plurality of movable lens groups that are moved for zooming, the zoom lens system comprising: in at least one of the movable lens groups, at least one negative lens element made of a material that fulfills conditional formulae (1) and (2) below; and in at least one of the movable lens groups, at least one positive lens element made of a material that fulfills conditional formulae (3), (4), and (5) below, the negative and positive lens elements moving in a same direction along an optical axis during zooming: Vd< 55 (1) 0.0018× Vd+P< 0.65 (2) 60< Vd (3) 0.645<0.0018× Vd+P (4) 9×10 −6 <dN/dT (5) where Vd represents an Abbe number for a d-line, P =( Ng−NF )/( NF−NC ), Ng represents a refractive index for a g-line, NF represents a refractive index for a F-line, NC represents a refractive index for a C-line, and dN/dT represents a rate of variation in refractive index accompanying variation in temperature around room temperature.