Patent ID: 6462886
Filing Date: 2002-10-08
Classification: G02B

Abstract:
An optical device comprising:a zoom lens system having an optical system which comprises a plurality of lens units and which achieves zooming by varying unit-to-unit distances; and an image sensor for converting an optical image formed by the zoom lens system into an electrical signal, wherein the zoom lens system comprises at least, from an object side thereof to an image side thereof, 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, and a fourth lens unit having a positive optical power, wherein, during zooming from wide-angle to telephoto, the fourth lens unit is moved toward the object side of said zoom lens system in a zoom range from wide-angle to a middle-focal-length position and toward the image side of said zoom lens system in a zoom range from the middle-focal-length position to telephoto, and wherein the following conditional formula is satisfied: 91/fW<30 â€ƒwhere f1 represents a focal length of the first lens unit; and fW represents a focal length of an entirety of said optical system at the wide-angle.