Nippon Kogaku K.k.

Soichi Nakamura

Yoshinari Hamanishi

Yutaka Iizuka

Yozo Iida

Kunio Konno

Kiyoshi Hayashi

Norio Mizutani

A beam splitter extracts a light beam from light passing through a picture-taking lens system, and a viewfinder optical system directs the light beam to a viewfinder eyepiece. The optical system includes a focus screen, a master lens for imaging the light beam on the focus screen, a pentaroof prism disposed between the master lens and the focus screen, and an eyepiece for observing therethrough the image on the focus screen.

Viewfinder optical arrangement of a camera

There is described an optical finder system for use with video cameras of the type having a tri-color separation color filter. Positioned in the finder optical path is an optical member onto which the image of an object to be picked up is projected and the optical member has an irregular pattern which is the same or similar to that of the color filter, whereby Moire fringes similar to those produced by the object image in cooperation with the color filter are produced on the finder focussing or imaging surface.

Optical finder system for a video camera

A short distance zoom lens system for forming an image of an object lying at any short distance at a predetermined short distance comprises, in order from the object side, a first group which is a divergent lens group, a second group which is a convergent lens group, and a third group which is a divergent lens group. The second and the third group are movable relative to each other in the direction of the optic axis to effect a magnification change. The first group is stationary during the magnification change and is movable in the direction of the optic axis independently of the second and third groups in accordance with the distance to the object.

Short distance zoom lens system

A Gauss type photographic lens comprises a first convergent lens group G1 and a second convergent lens group G2. The first convergent lens group G1 comprises, in the order from the object side, a positive lens component L1, a positive meniscus lens component L2 having its convex surface facing the object side, and a negative meniscus lens component L3 having its convex surface facing the object side, and the second convergent lens group G2 comprises, in the order from the object side, a meniscus lens component L4 consisting of a negative lens and a positive lens cemented together and having its concave surface facing the object side, and a positive lens component L5. Such a lens arrangement is well-known and to maintain the lens construction more compact and better correct the various aberrations, it is necessary that conditions be satisfied.

Gauss type photographic lens

A rear conversion lens comprises a divergent forward lens group comprising three components and a divergent rearward lens group comprising two components. The three components forming the forward lens group are, in order from the object side, a biconvex positive lens, a biconcave negative lens with its more curved surface facing the image side, and a positive lens with its more curved surface facing the object side. The two components forming the rearward lens group are, in order from the object side, a biconcave negative lens with its more curved surface facing the image side and a biconvex positive lens with its more curved surface facing the object side.

Rear conversion lens

In a wide angle zoom lens system comprising a diverging lens group and a converging lens group which are both movable on the optical axis of the lens system to vary the air space between the two groups so that the magnification of the image is variable while the image plane is being maintained at a fixed position, the diverging lens group comprises, in order from the object side, a negative meniscus lens component convex to the object side, a positive lens component, a negative lens component, a positive meniscus lens component convex to the object side, the four lens components being separate from one another, and an air chamber having a converging effect being formed between the second and the third lens component, the third and the fourth lens component being so disposed that the air space therebetween is greater than the center thickness of the third member, and the converging lens group comprises at least four positive lens components a positive lens component out of which is closest to the object side and a positive lens component out of which is closest to the image side, and a negative lens component disposed among the at least four positive lens components, these five lens components being separate from one another.

Wide angle zoom lens system

A telephoto lens with large relative aperture comprises a first converging lens group, a diverging lens group and a second converging lens group arranged in this order as viewed from the object side. The first converging lens group has two positive lens components and a negative lens component spaced from each other by an air space, the group remaining fixed when focusing. The diverging lens group has a cemented negative lens component and a negative lens component with an air space therebetween which is larger than the sum of the center thickness of the former component and the center thickness of the latter component. The second converging lens group comprises a cemented lens component and remains fixed when focusing. The first converging lens group and the diverging lens group virtually form an afocal system for an object at infinity. The diverging lens group is movable along the optical axis toward the image side for focusing upon an object at a shorter distance and also toward the object side for focusing upon an object at a longer distance.

Telephoto lens with large relative aperture

The wide-angle zoom lens system comprises a divergent lens group and a convergent lens group in the order from the object side, both of the lens groups being movable on the optical axis of the lens system to vary the air space between the two groups so that the magnification of the image is variable while the image plane is being maintained at a fixed position. The divergent lens group includes four air-spaced components which are, in the order from the object side, a first positive component with the more curved surface facing the object side, a first negative component with the more curved surface facing the image side, a second negative component with the more curved surface facing the image side and a first positive meniscus component convex to the object side. The first positive component and the first negative component define therebetween an air chamber having convergent power. The first negative component and the second negative component define therebetween an air chamber having divergent power with its more curved surface facing the object side. The axial space between the second negative component and the first positive meniscus component is greater than the space between the first positive component and the first negative component. The convergent lens group includes at least four positive components and a negative component intervening among the positive components, all components being separated from one another.

Wide-angle zoom lens system

In a wide angle zoom lens system which comprises a diverging lens group and a converging lens group in order from the object side and in which both of the groups are movable on the optical axis of the lens system to vary the air space between the two groups so that the magnification of the image is variable while the image plane is being maintained at a fixed position, the diverging lens group comprises, in order from the object side, a negative meniscus lens component convex to the object side, a negative meniscus lens component convex to the object side, and a positive meniscus lens component convex to the object side, and the converging lens group comprises at least four positive lens components which are separate from one another, a positive lens component being closest to the object side, a positive lens compartment being closest to the image and a negative lens component disposed among the at least four positive lens components.

A rear conversion lens system to be mounted on the image side of a photographic lens to enlarge the total focal length of the entire lens system including the photographic lens comprises a diverging group and a converging group disposed on the image side of the diverging group. The diverging group includes, as viewed in order from the object side, a first positive lens component, a negative lens component and a second positive lens component. The converging group includes, as viewed in order from the object side, a positive lens component and a negative lens component.

A telephoto lens system consists of a first convergent group and a divergent group disposed rearwardly of the first group for forming a substantially afocal converter, and a second convergent group disposed rearwardly of said divergent group. The first convergent lens group and the divergent lens group are movable relative to each other along the optical axis of the lens system for effecting focusing.

Telephoto lens system

A zoom lens system for a projector has three groups of lenses. The first lens group closest to the object has a composite converging function achieved by a doublet consisting of a first positive lens and a first negative lens. The second lens group is located between the other groups and is movable along the optical axis of the lens system relative to the other groups for varying magnification. It has a composite diverging function achieved by a doublet consisting of a second negative lens and a second positive meniscus lens. The third lens group most remote from the object has a composite converging function achieved by a third biconvex positive lens, a fourth positive lens, a forward meniscus lens consisting of a fifth positive lens joined to a third negative lens and having the convex surface thereof facing the object, a rearward meniscus lens consisting of a fourth negative lens joined to a sixth positive lens and having the concave surface thereof facing the object, a seventh biconvex positive lens, and an eighth positive lens.

Zoom lens for a projector

A zoom lens system which is also capable of ultra-closeup photography comprises in succession, as viewed from the object side of the lens system, a focusing lens group of positive power, a variator lens group of negative power, a compensator lens group of positive power and a master lens group of positive power, the variator and compensator lens groups being movable to provide the zooming action. When the lens groups are positioned to provide the minimum zooming focal length configuration of the lens system, the compensator lens groups may be moved toward the master lens group through a distance equal to the maximum amount of its movement during the zooming operation to form a lens system for use in ultra-closeup photography, wherein the focusing, variator and compensator lens groups together form a composite lens group having a focal length equal to or less than the focal length of the master lens group. The focal point of this composite lens group, as viewed from the image side of the lens system, lies on the side of the focusing lens group which faces away from the variator lens group. Alternatively, when the lens groups are positioned to provide the maximum zooming focal length configuration, the variator lens group may be moved toward the focusing lens group through a distance equal to the maximum amount of its movement during zooming operation to form the above-described lens system for ultra-closeup photography.

Growing community of inventors

Kamakura, Japan

Soichi Nakamura