Negative-lead optical zoom having three lens groups

An optical zoom includes three, respectively negative, positive and positive lens groups. The first lens group (G1) includes a negative lens (L1) and a positive lens (L2). The second lens group (G3) includes a positive lens, a negative lens and an aspherical plastic lens. The third lens group (G3) i...

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Bibliographic Details
Main Author NODA, TAKAYUKI
Format Patent
LanguageEnglish
French
German
Published 16.07.2008
Subjects
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
OPTICS
PHYSICS
PICTORIAL COMMUNICATION, e.g. TELEVISION
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Summary:An optical zoom includes three, respectively negative, positive and positive lens groups. The first lens group (G1) includes a negative lens (L1) and a positive lens (L2). The second lens group (G3) includes a positive lens, a negative lens and an aspherical plastic lens. The third lens group (G3) includes a positive lens. During zooming, the first and second lens groups are independently moved from each other. The first lens group of the optical zoom satisfies the following inequalities: |fg2/f1g|>1,8 and Xp<73 where fg2 denotes the focal length of the second lens L2, f1g denotes the focal lens of the first lens group (G1) and Xp = Np2 2 ×Vp2 where Np2 and Vp2 respectively denote the refractive index and Abbe number of the second lens L2, which is made of plastic.
Bibliography:Application Number: EP20080005474