Fisheye lens and imaging device using it
First Claim
1. A fisheye lens comprising two lens groups, arranged in order from the object side, as follows:
- a first lens group having negative refractive power; and
a second lens group having positive refractive power;
wherein the fisheye lens has a field angle of at least one hundred sixty degrees;
said first lens group includes, arranged in order from the object side, two lens elements, each having negative refractive power and a meniscus shape with the convex surface on the object side, a lens element having negative refractive power with a concave surface on the image side, and two lens elements, one having positive refractive power and one having negative refractive power;
said second lens group includes, arranged in order from the object side, two lens elements, one having positive refractive power and one having negative refractive power, a stop, and two lens elements, one having positive refractive power and one having negative refractive power; and
the on-axis distance between the image-side surface of said first lens group and the object-side surface of said second lens group is greater than the on-axis distance between any other adjacent surfaces of any of the lens elements of the fisheye lens.
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Accused Products
Abstract
A fisheye lens with a field angle of at least one hundred sixty degrees is formed of two lens groups, arranged in order from the object side, as follows: a first lens group having negative refractive power and a second lens group having positive refractive power. The first lens group includes, arranged in order from the object side, two lens elements, each having negative refractive power and a meniscus shape with the convex surface on the object side, a lens element having negative refractive power with a concave surface on the image side, and two lens elements of opposite refractive powers. The second lens group includes, arranged in order from the object side, two lens elements of opposite refractive powers, a stop, and two lens elements of opposite refractive powers. The fisheye lens preferably satisfies specified conditions related to spacings of lens surfaces and to distortion characteristics of the fisheye lens.
12 Citations
20 Claims
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1. A fisheye lens comprising two lens groups, arranged in order from the object side, as follows:
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a first lens group having negative refractive power; and
a second lens group having positive refractive power;
wherein the fisheye lens has a field angle of at least one hundred sixty degrees;
said first lens group includes, arranged in order from the object side, two lens elements, each having negative refractive power and a meniscus shape with the convex surface on the object side, a lens element having negative refractive power with a concave surface on the image side, and two lens elements, one having positive refractive power and one having negative refractive power;
said second lens group includes, arranged in order from the object side, two lens elements, one having positive refractive power and one having negative refractive power, a stop, and two lens elements, one having positive refractive power and one having negative refractive power; and
the on-axis distance between the image-side surface of said first lens group and the object-side surface of said second lens group is greater than the on-axis distance between any other adjacent surfaces of any of the lens elements of the fisheye lens. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification