Optical: systems and elements – Lens – With variable magnification
Patent
1996-09-27
1998-09-08
Epps, Georgia Y.
Optical: systems and elements
Lens
With variable magnification
359684, 359679, 359691, 359740, 359753, G02B 1514, G02B 900, G02B 1304
Patent
active
058053492
ABSTRACT:
A retrofocus type lens uses a rear focus method that provides high image forming performance. A retrofocus type lens includes, from an object side, a first lens group G.sub.1 having negative refractive power, which has a negative meniscus lens component L.sub.A having a convex surface facing an object side and a positive lens component L.sub.8 positioned closer to the image side than the negative meniscus lens component L.sub.A. At least one surface among all of the lens surfaces of the first lens group G.sub.1 is aspheric. A second lens group G.sub.2 is provided and has positive refractive power. The second lens group G2 has, from the object side, a front group G.sub.2F and a rear group G.sub.2R having positive refractive power. Focusing on a near object point is accomplished by moving the front group G.sub.2F and the rear group G.sub.2R of the second lens group with different moving amounts. When the moving amount of the front group G.sub.2F and the rear group G.sub.2R, during focusing from the infinite object point and the near object point are defined as X.sub.F and X.sub.R, respectively, the following condition is satisfied:
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Epps Georgia Y.
Lester Evelyn A.
Nikon Corporation
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