Patent ID: 7277234
Filing Date: 2007-10-02
Classification: G02B

Abstract:
1. A zoom lens system comprising in order from an object side to an image side: a first lens unit having a positive optical power; a second lens unit having a negative optical power; a third lens unit having a positive optical power, the third lens unit consisting of, in order from the object side to the image side, a first lens sub-unit including a positive lens element with an object-side surface which has convex shape and having a positive refractive power, an aperture stop, a second lens sub-unit including a negative lens element and having a negative optical power, and a third lens sub-unit including a positive lens element and having a positive optical power; and a fourth lens unit having a positive optical power, wherein a distance between the respective lens units is changed during zooming; wherein at least one of the first lens unit and the third lens unit is not moved for zooming; and the following conditions are satisfied: where f