Patent ID: 9019622
Filing Date: 2015-04-28
Classification: G02B,Y10T

Abstract:
1. A zoom lens comprising, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power, the first lens group including only, in order from the object, a cemented lens of a negative lens and a positive lens, and a positive meniscus lens having a convex surface facing the object, an aperture stop for determining brightness being disposed to the object side of the third lens group, all of the four groups moving and the aperture stop moving together with the third lens group upon zooming, and the following conditional expression being satisfied: where νdp1 denotes an Abbe number of the positive lens, which is disposed closest to the object in the first lens group, at the d-line as a standard, and the fourth lens group includes only a cemented lens of a positive lens and a negative lens which are disposed in order from the object.