Zoom Lens
First Claim
1. A zoom lens consisting of a front lens group having a negative power as a whole, and a rear lens group having a positive power as a whole and including a stop therein, arranged in this order from an object side, wherein the front and rear lens groups are moved relative to each other on an optical axis for zooming, whereas only a positive lens placed at a rearmost position of the rear lens group in the order from the object side is moved for focusing, and the zoom lens satisfies the following conditions:
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space="preserve" listing-type="equation">0.5<
ff/fR<
5.0
space="preserve" listing-type="equation">0.01<
β
f<
1.00
space="preserve" listing-type="equation">-1.0≦
r1/r2≦
0.3wherein fR represents a synthetic focal length of the rear lens group, ff represents a focal length of the rearmost positive lens, β
f represents an image magnification of the rearmost positive lens, r1 represents a radius of curvature of an object side surface of the rearmost positive lens, and r2 represents a radius of curvature of an image side surface of the rearmost positive lens.
3 Assignments
0 Petitions
Accused Products
Abstract
A zoom lens includes a front lens group having a negative power as a whole and a rear lens group having a positive power as a whole, and a stop included therein. For zooming, the front and rear lens groups are moved relative to each other on an optical axis. For focusing, only a rearmost positive lens of the rear lens group is moved. The zoom lens satisfies the following conditions:
0.5<ff/fR<5.0
0.01<βf<1.00
-1.0≦r1/r2≦0.3
wherein fR represents a synthetic focal length of the rear lens group, ff represents a focal length of the rearmost positive lens, βf represents an image magnification of the rearmost positive lens, r1 represents a radius of curvature of an object side surface of the rearmost positive lens, and r2 represents a radius of curvature of an image side surface of the rearmost positive lens.
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Citations
16 Claims
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1. A zoom lens consisting of a front lens group having a negative power as a whole, and a rear lens group having a positive power as a whole and including a stop therein, arranged in this order from an object side, wherein the front and rear lens groups are moved relative to each other on an optical axis for zooming, whereas only a positive lens placed at a rearmost position of the rear lens group in the order from the object side is moved for focusing, and the zoom lens satisfies the following conditions:
-
space="preserve" listing-type="equation">0.5<
ff/fR<
5.0
space="preserve" listing-type="equation">0.01<
β
f<
1.00
space="preserve" listing-type="equation">-1.0≦
r1/r2≦
0.3wherein fR represents a synthetic focal length of the rear lens group, ff represents a focal length of the rearmost positive lens, β
f represents an image magnification of the rearmost positive lens, r1 represents a radius of curvature of an object side surface of the rearmost positive lens, and r2 represents a radius of curvature of an image side surface of the rearmost positive lens. - View Dependent Claims (2, 3)
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4. A zoom lens, comprising:
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a front lens group having a meniscus negative lens and a positive lens, arranged in this order from an object side, wherein the meniscus negative lens and positive lens are convex on the object side; and a rear lens group having first and second positive lenses, a negative lens having concave surfaces on opposite sides, and a rearmost positive lens, arranged in this order from an object side, and including a stop therein, wherein the front and rear lens groups are moved relative to each other on an optical axis for zooming, wherein only said positive lens located at a rearmost position of the rear lens group in the order from the object side is moved for focusing, and wherein the zoom lens satisfies the following conditions;
space="preserve" listing-type="equation">0.5<
ff/fR<
5.0
space="preserve" listing-type="equation">0.01<
β
f<
1.00
space="preserve" listing-type="equation">-1.0≦
r1/r2≦
0.3where fR represents a synthetic focal length of the rear lens group, ff represents a focal length of the rearmost positive lens, β
f represents an image magnification of the rearmost positive lens, r1 represents a radius of curvature of an object side surface of the rearmost positive lens, and r2 represents a radius of curvature of an image side surface of the rearmost positive lens. - View Dependent Claims (5, 6, 7, 8, 9)
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10. A zoom lens, comprising:
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a front lens group having a meniscus negative lens and a positive lens, arranged in this order from an object side, wherein the meniscus negative lens and positive lens are convex on the object side; and a rear lens group having a first positive lens, a negative lens having concave surfaces on opposite sides, and a rearmost positive lens, arranged in this order from an object side, and including a stop therein, wherein the front and rear lens groups are moved relative to each other on an optical axis for zooming, wherein only said positive lens located at a rearmost position of the rear lens group in the order from the object side is moved for focusing, and wherein the zoom lens satisfies the following conditions;
space="preserve" listing-type="equation">0.5<
ff/fR<
5.0
space="preserve" listing-type="equation">0.01<
β
f<
1.00
space="preserve" listing-type="equation">-1.0≦
r1/r2≦
0.3where fR represents a synthetic focal length of the rear lens group, ff represents a focal length of the rearmost positive lens, β
f represents an image magnification of the rearmost positive lens, r1 represents a radius of curvature of an object side surface of the rearmost positive lens, and r2 represents a radius of curvature of an image side surface of the rearmost positive lens. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification