Abstract: An image forming lens system includes an aperture stop, and an image-side lens unit group which is disposed on an image side of the aperture stop. The image-side lens unit group includes a first image-side lens unit having a negative refractive power, a second image-side lens unit having a positive refractive power, and a third image-side lens unit having a negative refractive power. Any one of the first image-side lens unit, the second image side lens unit, and the third image-side lens unit is a focusing lens unit which moves along the optical axis at the time of focusing, and the following conditional expression (1) is satisfied: 0.06<|ffo/f|<0.4 ??(1) where, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and ffo denotes a focal length of the focusing lens unit.

Abstract: A wide-angle optical system includes a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power. At the time of carrying out a focal-position adjustment, the second lens unit is moved. The third lens unit includes a positive single lens on an image side of a cemented surface Sc having a negative refractive power nearest to an image in the third lens unit, and has a plurality of refractive surfaces having a negative refractive power on the object side of the cemented surface Sc. The third lens unit has at least one refractive surface Sp having a positive refractive power which satisfies following conditional expression (1): 0.02<fL/Rsp<1.20??(1).

Abstract: A wide-angle optical system is a wide-angle optical system having a lens component, and includes in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. At the time of carrying out a focal-position adjustment from a far point to a near point, the second lens unit is moved from a first position toward a second position. The third lens unit includes not less than three lens components. Not less than three lens components include a first lens component and a second lens component. Each of the first lens component and the second lens component has a positive refractive power, and following conditional expression (1) is satisfied: 0.8<f3L12/fL<6.0??(1).

Abstract: A wide-angle optical system includes in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third unit having a positive refractive power. At the time of carrying out a focal-position adjustment from a far point to a near point, the second lens unit is moved from a first position toward a second position. The third lens unit includes not less than three lens components, and not less than three lens components include a first lens component and a second lens component. The first lens component is a single lens and the second lens component is a cemented lens. Following conditional expression (1) is satisfied: ?0.60<(n2C??n2C)/r2C<?0.05??(1).

Abstract: Provided is a method for manufacturing an exercise ball which is made by using a pasted ball such as a soft leather ball and which has a lower impact value compared to a conventional yarn-wound ball. The exercise ball comprises a spherical hollow rubber bladder (2) in which compressed air is sealed, and a yarn-wound reinforcement layer (3) formed by evenly winding a filament yarn around the surface of the rubber bladder, wherein the exercise ball is characterized in that nylon filament yarn, obtained by hard twisting two 30-50 denier nylon filaments 1-a, 1-b in a single-direction twist is used as a winding yarn (1).

Abstract: A wide-angle optical system is a wide-angle optical system having a lens component. The lens component has a plurality of optical surfaces, in the lens component, two optical surfaces are in contact with air, and at least one optical surface is a curved surface. The wide-angle optical system includes in order from an object side, a first lens unit having a negative refractive power, a second lens unit, and a third lens unit having a positive refractive power. The second lens unit, for a focal-position adjustment, is moved between a first position and a second position along an optical axis. The third lens unit includes a cemented lens having a positive refractive power and a cemented lens having a negative refractive power, and following conditional expression (1) is satisfied: 0.05<fL/R31F<1.0 ??(1).

Abstract: Provided is a method for manufacturing an exercise ball which is made by using a pasted ball such as a soft leather ball and which has a lower impact value compared to a conventional yarn-wound ball. The exercise ball comprises a spherical hollow rubber bladder (2) in which compressed air is sealed, and a yarn-wound reinforcement layer (3) formed by evenly winding a filament yarn around the surface of the rubber bladder, wherein the exercise ball is characterized in that nylon filament yarn, obtained by hard twisting two 30-50 denier nylon filaments 1-a, 1-b in a single-direction twist is used as a winding yarn (1).

Abstract: A zoom lens includes a front unit having a negative refractive power; and a rear unit having a positive refractive power, which includes an aperture stop. The front unit includes a first negative refractive power lens, a second negative refractive power lens, and a third positive refractive power lens. The first lens is nearest to an object, and has a meniscus shape with a convex surface directed toward the object side, and the second lens is on an image side of the first lens, and has a meniscus shape with a convex surface directed toward the object side. The rear unit includes a first lens unit A and a second lens unit B, wherein when zooming from a wide angle end to a telephoto end, a distance between the front unit and the rear unit narrows, and a distance between the first lens unit A and the second lens unit B changes. The first lens unit A includes a first sub-lens unit having a positive refractive power, the aperture stop, and a second sub-lens unit.

Abstract: A variable magnification optical system includes a plurality of lens element, and includes 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 at least one lens unit. An aperture stop is either positioned between the second lens unit and the third lens unit, or positioned in the third lens unit. At the time of zooming from a wide angle end to a telephoto end, the first lens unit is fixed, the second lens unit moves from the object side to an image-plane side, and at least one of lens units positioned on an image side of the aperture stop moves. The first lens unit includes at least four positive lens elements and at least two negative lens elements.

Abstract: A variable magnification optical system includes 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 at least one lens unit. A second predetermined positive lens element satisfies conditional expressions (1) and (2) and a second predetermined negative lens element satisfies the following conditional expressions (3) and (4). The second lens unit includes three sub-lens units and the following conditional expressions (5) and (6) are satisfied: 0.520<(?g,F)G2p<0.610??(1), 0.680<(?C,t)G2p<0.900??(2), 0.520<(?g,F)G2n<0.560??(3), 0.750<(?C,t)G2n<0.900??(4), ?0.25<fG21/fG22<0.90??(5), and ?0.70<fG21/fG23<0.40??(6).

Abstract: An image forming lens system includes an aperture stop, and an image-side lens unit group which is disposed on an image side of the aperture stop. The image-side lens unit group includes a first image-side lens unit having a negative refractive power, a second image-side lens unit having a positive refractive power, and a third image-side lens unit having a negative refractive power. Any one of the first image-side lens unit, the second image side lens unit, and the third image-side lens unit is a focusing lens unit which moves along the optical axis at the time of focusing, and the following conditional expression (1) is satisfied: 0.06<|ffo/f|<0.4 ??(1) where, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and ffo denotes a focal length of the focusing lens unit.

Abstract: An image forming lens system includes an aperture stop, and an image-side lens unit group which is disposed on an image side of the aperture stop. The image-side lens unit group includes a first image-side lens unit having a negative refractive power, a second image-side lens unit having a positive refractive power, and a third image-side lens unit having a negative refractive power. Any one of the first image-side lens unit, the second image side lens unit, and the third image-side lens unit is a focusing lens unit which moves along the optical axis at the time of focusing, and the following conditional expression (1) is satisfied: 0.06<|ffo/f|<0.4??(1) where, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and ffo denotes a focal length of the focusing lens unit.

Abstract: A zoom lens includes in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power, and at the time of zooming, movement of the first lens unit includes at least a movement toward an image side, the second lens unit moves integrally with an aperture stop, and the third lens unit moves toward the object side, and the first lens unit includes at least a negative lens and a positive lens, and the negative lens is disposed nearest to an object, and the following conditional expressions are satisfied: 0.75<(?2t/?2w)/(?3t/?3w)<1.38 ?0.70<?2w<?0.32 0.96<f2/fw<1.80.

Abstract: A variable magnification optical system includes 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 at least one lens unit. A second predetermined positive lens element satisfies conditional expressions (1) and (2) and a second predetermined negative lens element satisfies the following conditional expressions (3) and (4). The second lens unit includes three sub-lens units and the following conditional expressions (5) and (6) are satisfied: 0.520<(?g,F)G2p<0.610??(1), 0.680<(?C,t)G2p<0.900??(2), 0.520<(?g,F)G2n<0.560??(3), 0.750<(?C,t)G2n<0.900??(4), ?0.25<fG21/fG22<0.90??(5), and ?0.70<fG21/fG23<0.40??(6).

Abstract: A variable magnification optical system includes a plurality of lens element, and includes 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 at least one lens unit. An aperture stop is either positioned between the second lens unit and the third lens unit, or positioned in the third lens unit. At the time of zooming from a wide angle end to a telephoto end, the first lens unit is fixed, the second lens unit moves from the object side to an image-plane side, and at least one of lens units positioned on an image side of the aperture stop moves. The first lens unit includes at least four positive lens elements and at least two negative lens elements.

Abstract: A zoom lens includes a front unit having a negative refractive power; and a rear unit having a positive refractive power, which includes an aperture stop. The front unit includes a first negative refractive power lens, a second negative refractive power lens, and a third positive refractive power lens. The first lens is nearest to an object, and has a meniscus shape with a convex surface directed toward the object side, and the second lens is on an image side of the first lens, and has a meniscus shape with a convex surface directed toward the object side. The rear unit includes a first lens unit A and a second lens unit B, wherein when zooming from a wide angle end to a telephoto end, a distance between the front unit and the rear unit narrows, and a distance between the first lens unit A and the second lens unit B changes. The first lens unit A includes a first sub-lens unit having a positive refractive power, the aperture stop, and a second sub-lens unit.

Abstract: A zoom lens includes a front unit having a negative refractive power and a rear unit having a positive refractive power, which includes an aperture stop, and the front unit includes a first lens having a negative refractive power, and the first lens has a meniscus shape of which a convex surface is directed toward the object side, and the rear unit includes a first lens unit A and a second lens unit B, and at the time of zooming from a wide angle end to a telephoto end, a distance between the front unit and the rear unit changes.

Abstract: An image forming lens system includes a front lens unit having a positive refractive power, and a rear lens unit, and does not include any other lens unit. The front lens unit includes a first lens unit having a positive refractive power and a second lens unit having a negative refractive power. Each of the first lens unit and the second lens unit includes a positive lens and a negative lens. The second lens unit is a focusing lens unit. The rear lens unit includes a positive lens and a negative lens. The second lens unit is the only lens unit that moves, in the front lens unit, and the following conditional expressions (1) and (2?) are satisfied: 0.5<fFF/f<1.65??(1) 0?|f/rG2b|<6.5??(2?).

Abstract: A zoom lens comprising in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a negative refractive power, a lens unit having a positive refractive power, and a rearmost lens unit having a negative refractive power, and the rearmost lens unit is positioned nearest to an image in the plurality of lens units, and at the time of zooming, distances between the lens units in the plurality of lens units change. Moreover, an image pickup apparatus includes the zoom lens, and an image pickup element having an image pickup surface.

Abstract: A zoom lens includes a front unit having a negative refractive power and a rear unit having a positive refractive power, which includes an aperture stop, and the front unit includes a first lens having a negative refractive power, and the first lens has a meniscus shape of which a convex surface is directed toward the object side, and the rear unit includes a first lens unit A and a second lens unit B, and at the time of zooming from a wide angle end to a telephoto end, a distance between the front unit and the rear unit changes.