REAR FOCUS TYPE ZOOM LENS

摘要

PROBLEM TO BE SOLVED: To have satisfactory performance and a high variable power ratio over all zoom areas and all object distance ranges by composing a zoom lens of plural lens groups and making the focal length of a lens or the like satisfy specified formulas. SOLUTION: This lens has a first lens group L1 having a positive refracting power, a second lens group L2 having a negative refracting power, a third lens group L3 having a positive refracting power and a fourth lens group L4 having a positive refracting power successively from the side of an object. The first lens group L1 is composed of a 11th lens having a negative refracting power, a 12th lens having a positive refracting power and 13th lens having a positive refracting power from the object side and the second lens group L2 is composed of three negative lenses and one positive lenses. When the focal length of the 12th lens is defined as f12, a focal length at the telescopic end of all systems is defined as Ft, the Abbe number of the 12th lens is defined asν12 and the focal length of an i-th lens group is defined as Fi, the conditions of 0.95