Abstract: First, second, third, and fourth lenses (in order from an object side) are arranged between the object and an image sensor where an image of the object is formed. The first lens may have a positive refractive power and may be a meniscus lens that is convex toward the object. The second lens may have a positive refractive power and may be a meniscus lens that is convex toward the image sensor. The third lens may have a positive refractive power and may be a meniscus lens that is convex toward the image sensor. At least one of an incident surface and an exit surface of the fourth lens may be an aspherical surface. The fourth lens may have a negative refractive power or a positive refractive power. A viewing angle ? of the lens optical system may satisfy a conditional expression, 2.5<|tan ?|<3.5.

Abstract: A lens optical system including first, second, third, fourth, and fifth lenses that are sequentially arranged between an object and an image sensor on which an image of the object is formed. The first lens may have a positive refractive power and may be biconvex. The second lens may have a negative refractive power and may have a meniscus shape that is convex toward the object. The third lens may have a positive refractive power. The fourth lens may have a positive refractive power and may have a meniscus shape that is convex toward the image sensor. The fifth lens may have a negative refractive power, and at least one of an incident surface and an exit surface of the fifth lens may be an aspherical surface.

Abstract: A lens optical system includes first, second, third, fourth, and fifth lenses that are arranged between an object and an image sensor where an image of the object is formed, in order from an object side, wherein the first lens has a positive (+) refractive power and an incident surface that is convex toward the object, the second lens has a negative (?) refractive power and a meniscus shape that is convex toward the object, the third lens has a positive (+) refractive power and both convex surfaces, the fourth lens has a positive (+) refractive power and a meniscus shape that is convex toward the image sensor, and the fifth lens has a negative (?) refractive power and an incident surface and an exit surface, at least one of the incident surface and the exit surface is an aspherical surface.

Abstract: A lens optical system includes first, second, third, and fourth lenses that are arranged between an object and an image sensor, in order from an object side, wherein the first lens has positive refractive power and an incident surface that is convex toward the object, the second lens has negative refractive power and both surfaces of which are concave, the third lens has positive refractive power and a meniscus shape that is convex toward the image sensor, and the fourth lens has negative refractive power and at least one of an incident surface and an exit surface of which is an aspherical surface, wherein the system satisfies the inequality, 3.0<TTL/BL<3.4, wherein TTL is a distance from the incident surface of the first lens to the image sensor and BL is a distance from the exit surface of the fourth lens to the image sensor.

Abstract: First, second, third, and fourth lenses (in order from an object side) are arranged between the object and an image sensor where an image of the object is formed. The first lens may have a positive refractive power and may be a meniscus lens that is convex toward the object. The second lens may have a positive refractive power and may be a meniscus lens that is convex toward the image sensor. The third lens may have a positive refractive power and may be a meniscus lens that is convex toward the image sensor. At least one of an incident surface and an exit surface of the fourth lens may be an aspherical surface. The fourth lens may have a negative refractive power or a positive refractive power. A viewing angle ? of the lens optical system may satisfy a conditional expression, 2.5<|tan ?|<3.5.

Abstract: An imaging lens system includes, sequentially from an object side to an image side: a first lens having a positive refractive power; a second lens having a negative refractive power; and a third lens having a positive refractive power or a negative refractive power, wherein a viewing angle ? satisfies following condition,

Abstract: First, second, third, and fourth lenses (in order from an object side) are arranged between the object and an image sensor where an image of the object is formed. The first lens may have a positive refractive power and both surfaces thereof may be convex. The second lens may have a negative refractive power and both surfaces thereof may be concave. The third lens may have a positive refractive power and have a meniscus shape that is convex toward the image sensor. The fourth lens may have a negative refractive power and at least one of an incident surface and an exit surface thereof may be an aspherical surface. A sagittal depth SAG1 of an incident surface of the second lens along an optical axis and a sagittal depth SAG2 of an exit surface of the second lens along the optical axis may satisfy Inequality |SAG1|>|SAG2|.

Abstract: An imaging lens system includes, sequentially from an object side to an image side: a first lens having a positive refractive power; a second lens having a negative refractive power; and a third lens having a negative refractive power, wherein a viewing angle ? satisfies following condition, 0.3<|tan ?|<0.8.

Abstract: A lens optical system includes first to fourth lenses that are sequentially arranged from an object, and which are between the object and an image sensor on which an image of the object is formed. The first lens has a positive refractive power and an incident surface that is convex toward the object. The second lens has a negative refractive power and both surfaces that are concave. The third lens has a positive refractive power and has a meniscus shape that is convex toward the image sensor. The fourth lens has a negative refractive power and at least one of an incident surface and an exit surface thereof is an aspherical surface. The lens optical system may satisfy an inequality that 0.5<|tan ?|/f<1.5, where “?” denotes an angle of view of the lens optical system and “f” denotes a focal length of the lens optical system.

Abstract: Provided are a lens assembly and an optical system including the same. The lens assembly may include a first lens having a groove region, a second lens having an insertion region that is inserted into the groove region, and a light blocking member between the first lens and the second lens. The light blocking member may be disposed between a first surface portion of the first lens and a second surface portion of the second lens, and the light blocking member may be separated from at least one of the first surface portion and the second surface portion. The lens assembly may further include at least one additional lens. The lens assembly may be applied to various optical systems.

Abstract: Provided are a capsule-type image photographing apparatus and endoscopy using the same. The apparatus includes a shell unit having a globular shape and a main body unit capable of freely rotating in the shell unit. The main body unit includes an image photographing system, a wireless transmitter, a battery, a counterweight for determining the center of gravity of the main body unit, and an encapsulant for fixing the image photographing system, the wireless transmitter, the battery, and the counterweight. The apparatus may be a long-distance capsule-type image photographing apparatus or a short-distance capsule-type image photographing apparatus depending on the position of the counterweight. By use of the long- and short-distance capsule-type image photographing apparatuses, the interior of the tested person's body can be effectively photographed.

Abstract: A photographic lens optical system including: a first lens, a second lens, and a third lens sequentially arranged from a side of an object toward an image sensor, wherein the first lens has a positive (+) refractive power and an incident surface that is convex toward the object, the second lens has a negative (?) refractive power and is convex toward the image sensor, the third lens has a negative (?) refractive power, and at least one of an incident surface and an exit surface thereof is aspherical, and wherein an angle of view (?) of the lens optical system, and a focal length (f) of the lens optical system satisfy the following inequality: 1.0<|tan ?|/f<2.0.

Abstract: A lens optical system including, in a sequence from an object to an imaging device on which an image of the object is formed; a first lens having a a positive refractive power; a second lens having negative refractive power; a third lens having a a positive refractive power; and a fourth lens having a negative refractive power and an incident surface facing the object is concave and an exit surface facing the imaging device has an inflection point.

Abstract: A lens optical system having first to fourth lenses sequentially arranged from an object, and between the object and an image sensor on which an image of the object is formed. The first lens has a positive refractive power and is convex toward the object. The second lens has a negative refractive power and is biconcave. The third lens has a positive refractive power and is convex toward the image sensor. The fourth lens has a negative refractive power and at least one of an incident surface and an exit surface of the fourth lens is an aspherical surface. An aperture may be arranged between the first and second lenses.

Abstract: Provided are a capsule-type image photographing apparatus and endoscopy using the same. The apparatus includes a shell unit having a globular shape and a main body unit capable of freely rotating in the shell unit. The main body unit includes an image photographing system, a wireless transmitter, a battery, a counterweight for determining the center of gravity of the main body unit, and an encapsulant for fixing the image photographing system, the wireless transmitter, the battery, and the counterweight. The apparatus may be a long-distance capsule-type image photographing apparatus or a short-distance capsule-type image photographing apparatus depending on the position of the counterweight. By use of the long- and short-distance capsule-type image photographing apparatuses, the interior of the tested person's body can be effectively photographed.