Patent ID: 6490096
Filing Date: 2002-12-03
Classification: G02B

Abstract:
A zoom lens comprising, successively from an object side, a first lens group, fixed upon zooming, having a positive refracting power; a second lens group, movable upon zooming, having a negative refracting power; a third lens group, having a negative refracting power, for correcting a fluctuation of an image surface upon zooming; and a fourth lens group, fixed upon zooming, having a positive refracting power;wherein said second lens group comprises, successively from the object side, two meniscus lenses each having a negative refracting power with a convex surface directed onto the object side; and an achromatic lens comprising, successively from the object side, a cemented lens having a negative refracting power as a whole, and a lens having a positive refracting power with a convex surface directed onto the object side; said cemented lens comprising, successively from the object side, a meniscus lens or plane-convex lens having a positive refracting power with a concave surface or plane directed onto the object side, and a lens having a negative refracting power.