Zoom lens
First Claim
1. A zoom lens comprising, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, at least said second lens unit and said fourth lens unit being moved to vary magnification and said fourth lens unit being moved to effect focusing, wherein said third lens unit consists of one positive lens and one negative lens, and wherein an aperture stop is disposed between said positive lens and said negative lens.
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Accused Products
Abstract
A zoom lens comprises, in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, wherein at least the second and fourth lens units are moved to vary magnification and the fourth lens unit is moved to effect focusing, and wherein the third lens unit is composed of one positive lens and one negative lens and an aperture stop is disposed between the positive lens and the negative lens in the third lens unit.
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Citations
14 Claims
- 1. A zoom lens comprising, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, at least said second lens unit and said fourth lens unit being moved to vary magnification and said fourth lens unit being moved to effect focusing, wherein said third lens unit consists of one positive lens and one negative lens, and wherein an aperture stop is disposed between said positive lens and said negative lens.
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9. A zoom lens consisting of, in order from an object side to an image side, a first lens unit of positive refractive power stationary during zooming, a second lens unit of negative refractive power, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power, said second lens unit being moved toward the image side to effect zooming from a wide-angle end to a telephoto end and said fourth lens unit being moved to compensate for shifting of an image plane resulting from the zooming, and said fourth lens unit being moved to effect focusing, wherein the following condition is satisfied:
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space="preserve" listing-type="equation">0.8≦
TD/f.sub.T ≦
1.05where TD is a distance from the first lens surface, when counted from the object side, to a paraxial image plane with an optical element of no refractive power on the image side removed, and fT is a focal length in the telephoto end of said zoom lens. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification