Zoom lens device with five lens units

Details Zoom lens device with five lens units Zoom lens device with five lens units

1997-01-22

1998-04-14

Epps, Georgia Y.

Optical: systems and elements

Lens

With variable magnification

359676, 359708, G02B 1514, G02B 302

Patent

active

057399603

ABSTRACT:
A zoom lens device including a total of five lens units which are in order of lens units from the lens unit closest to an object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, a fourth lens unit having a positive refractive power, and a fifth lens unit having a positive refractive power. During magnification changes, the first, second, and fourth lens units move along the optical axis, while the third and fifth lens units are stationary. The zoom lens device satisfies the following conditions: (1) 0.7<f.sub.2 /f.sub.T <1.2; (2) 2.2<.vertline.f.sub.3 .vertline./f.sub.W <3.5; (3) 0.6<.vertline.f.sub.3 .vertline./f.sub.4 <1.45; and (4) f.sub.T <f.sub.4 <f.sub.5, where fi represents the focal length of the ith lens unit, and f.sub.T and f.sub.W represent the focal lengths at the telephoto end and the wide angle end, respectively.

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patent: 5528427 (1996-06-01), Tanaka et al.
patent: 5568321 (1996-10-01), Ogawa et al.
patent: 5576890 (1996-11-01), Tanaka et al.

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