Zoom lens

Details Zoom lens Zoom lens

1998-03-27

1999-12-14

Epps, Georgia

Optical: systems and elements

Lens

With variable magnification

359687, 359688, G02B 1514

Patent

active

06002528&

ABSTRACT:
A zoom lens including, in succession from the object side, a first positive lens unit (focal length f1), a second negative lens unit, a third lens unit, and a fourth positive lens unit, the second and third lens units moving for zooming, the first lens unit having, from the object side, a front lens subunit (focal length f11) fixed during focusing and a rear lens subunit (focal length f12) movable toward the object side for focusing on an infinity object to a short distance object, the front lens subunit having a cemented lens comprising a first negative lens (refractive power N111, Abbe number .nu.111) and a second positive lens (refractive power N112, Abbe number .nu.112) cemented together, the rear lens subunit having first and second positive lenses, wherein, where Ri is the radius of curvature of the ith lens surface from the object side:

REFERENCES:
patent: 3594066 (1971-07-01), Cook
patent: 4110006 (1978-08-01), Ikemori
patent: 5416639 (1995-05-01), Yamanashi
patent: 5737127 (1998-04-01), Tsutsumi
patent: 5737128 (1998-04-01), Usui
patent: 5790316 (1998-08-01), Terasawa et al.
patent: 5808809 (1998-09-01), Yahagi

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