Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2005-01-18
2005-01-18
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S676000
Reexamination Certificate
active
06844986
ABSTRACT:
In order to provide a zoom lens which has excellent optical performance with a compact configuration using a small number of constituent lenses, a zoom lens according to the present invention comprises a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power, which are sequentially arranged from the object side, wherein the gap between the first and second lens units is decreased, the space between the second and third lens units is increased in zooming from the side angle end to the telephoto end, the third lens unit has a cemented lens formed by cementing a positive lens element to a negative lens element, and is moved along the optical axis for zooming, and letting NLi be the number of lensess constituting the ith lens unit, a condition,in-line-formulae description="In-line Formulae" end="lead"?NL3<NL2≦NL1in-line-formulae description="In-line Formulae" end="tail"?is satisfied.
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Canon Kabushiki Kaisha
Choi William
Epps Georgia
Morgan & Finnegan , LLP
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