WIDE ANGLE LENS AND IMAGING DEVICE
First Claim
1. A wide angle lens whose field angle exceeds 160 degrees, comprising:
- a front group, an aperture stop, and a rear group, which are arranged in the stated order from an object side toward an image side, whereinthe front group includes a first lens that is a negative meniscus lens whose convex surface is facing the object side, a second lens that is a negative lens, a third lens that is a negative lens, and a fourth lens that is a positive lens, which are arranged in the stated order from the object side toward the image side,the rear group includes a fifth lens that is a positive lens, a sixth lens that is a negative lens, and a seventh lens that is a positive lens, which are arranged in the stated order from an aperture stop side toward the image side, wherein the fifth lens and the sixth lens are combined together forming a cemented lens having positive refractive power,the first to seventh lenses form an imaging system including a total of seven lenses,the fifth lens is made of a material having an Abbe number ν
d5 that is greater than or equal to 50,the sixth lens is made of a material having an Abbe number ν
d6 that is less than or equal to 30, anda surface of the seventh lens facing the image side is an aspheric surface.
1 Assignment
0 Petitions
Accused Products
Abstract
A wide angle lens whose field angle exceeds 160 degrees, includes a front group, an aperture stop, and a rear group arranged in this order from an object-side toward an image-side. The front group includes a first lens (negative meniscus) whose convex surface faces the object, a second lens (negative), a third lens (negative), and a fourth lens (positive), arranged in this order from the object-side toward the image-side. The rear group includes a fifth lens (positive), a sixth lens (negative), and a seventh lens (positive), arranged in this order from an aperture-side toward the image-side. The fifth and sixth lenses are combined, forming a cemented lens having positive refractive power. The fifth and sixth lenses are made of materials having Abbe numbers of greater than or equal to 50 and less than or equal to 30, respectively. A surface of the seventh lens facing the image is aspheric.
27 Citations
9 Claims
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1. A wide angle lens whose field angle exceeds 160 degrees, comprising:
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a front group, an aperture stop, and a rear group, which are arranged in the stated order from an object side toward an image side, wherein the front group includes a first lens that is a negative meniscus lens whose convex surface is facing the object side, a second lens that is a negative lens, a third lens that is a negative lens, and a fourth lens that is a positive lens, which are arranged in the stated order from the object side toward the image side, the rear group includes a fifth lens that is a positive lens, a sixth lens that is a negative lens, and a seventh lens that is a positive lens, which are arranged in the stated order from an aperture stop side toward the image side, wherein the fifth lens and the sixth lens are combined together forming a cemented lens having positive refractive power, the first to seventh lenses form an imaging system including a total of seven lenses, the fifth lens is made of a material having an Abbe number ν
d5 that is greater than or equal to 50,the sixth lens is made of a material having an Abbe number ν
d6 that is less than or equal to 30, anda surface of the seventh lens facing the image side is an aspheric surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification