Optical: systems and elements – Image stabilization – By movable refractive structure
Patent
1997-07-23
1998-11-10
Nelms, David C.
Optical: systems and elements
Image stabilization
By movable refractive structure
359682, 359684, 359686, 359715, 359740, G02B 2764, G02B 1514, G02B 302, G02B 900
Patent
active
058352724
ABSTRACT:
A zoom lens is provided such that it has a high image quality over its entire zooming range, an angle of view of 70.degree. or greater at a wide-angle end, a zooming ratio of 2.5 or greater, and an F-number of about 2.8 throughout the entire range. The zoom lens has a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power. The first, second, third and fourth lens groups are arranged in order from the object side of the zoom lens. The zoom lens also has an aperture stop. The third lens group has at least one concave aspheric surface. During zooming, at least the first, second and fourth lens groups are moved along the optical axis. The zoom lens satisfies the condition 0.5<(A.sub.w /l.sub.w)/(A.sub.t /l.sub.t)<1 when A.sub.w is a distance between the image plane and the lens plane that is located closest to the object side in the fourth lens group when the zoom lens is at a wide-angle end, A.sub.t is a distance between the image plane and the lens plane that is located closest to the object side in the fourth lens group when the zoom lens is at a telephoto end, l.sub.w is a distance between the image plane and the aperture stop at the wide-angle end, and l.sub.t is a distance between the image plane and the aperture stop at the telephoto end.
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Lester Evelyn A.
Nelms David C.
Nikon Corporation
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