Asahi Kogaku Kogyo Kabushiki Kaisha

Asahi Kogaku Kogyo K.k.

Pentax Corporation

Hoya Corporation

Asahi Kogaku Kabushiki Kaisha

Jun Hirakawa

Toru Chiba

Takayuki Ito

Koichi Maruyama

Tetsuji Shono

Yasunori Arai

Masaki Shimizu

A photographic lens system includes a positive lens element, a positive lens element, a negative lens element having a concave surface facing toward the image, a diaphragm, a negative lens element having a concave surface facing toward the object, a positive lens element which is cemented to the negative lens element, and two or three positive lens elements, in this order from the object. An intermediate negative lens element, having the weakest negative refractive power out of all of the negative lens elements, is provided between the negative lens element having the concave surface facing toward the image and the negative lens element having the concave surface facing toward the object.

Photographic lens system and electronic imaging device using the same

A fisheye lens system includes a negative first lens group and a positive second lens group, which are defined with respect to a maximum air-distance between lens elements constituting the fisheye lens system. The negative first lens group includes a first negative meniscus lens element having the convex surface facing toward the object, a second negative meniscus lens element having the convex surface facing toward the object, and a negative third lens element.

Fisheye lens system and a fisheye zoom lens system

A wide-angle lens system includes a negative first lens group, a negative second lens group, and a positive third lens group. The negative first lens group includes at least two negative meniscus lens elements each having the convex surface facing toward the object, and a positive lens element provided on the image-side of the two negative meniscus lens elements. The negative second lens group includes cemented lens elements and a negative meniscus lens element having the convex surface facing toward the object. The wide-angle lens system satisfies the following conditions:&#x3e;1.6&#x2003;&#x2003;(1)&#x3e;1.5&#x2003;&#x2003;(2)()/()&#x3e;1.0&#x2003;&#x2003;(3)

Wide-angle lens system

An adapter having a tilt and shift mechanism which is mounted between a camera body and a photographic lens to relatively tilt or shift the camera body. The photographic lens includes a body mount frame which is provided with a mount to which the camera body can be detachably mounted, a tilt frame which is connected to the body mount frame, and a shift frame which is provided with a lens mounting mount to which the photographic lens can be detachably mounted and which is connected to the tilt frame to linearly move in a direction intersecting the optical axis of the photographic lens. The tilt frame is connected to the body mount frame to move along an arc having a predetermined radius, the center of the radius being located on a center of an image surface.

Adapter having a tilt and shift mechanism

In a view finder having an objective lens, an indicator is provided in the vicinity of an image forming position of the objective lens. The indicator includes a liquid crystal cell having a pair of spaced first and second glass substrates with transparent electrodes. A transparent macromolecular substance having a liquid crystal dispersed therein is enclosed in the space between the first and second glass substrates. An eyepiece is provided through which an image formed by the objective lens can be viewed. Light sources are provided along side surfaces of the indicator to emit and make light incident upon the indicator.

View finder

A soft focus lens which is designed as a retrofocus type lens, comprises a front lens group having a negative power, a rear lens group having positive power, and a diaphragm located within the rear lens group. The front and rear lens groups are arranged in this order from an object side. In particular, the soft focus lens satisfies the following conditions;

Soft focus lens

A super wide angle zoom lens includes a first lens group of negative power and a rear lens group of positive power, in this order from the object side, so that zooming may be carried out by relatively moving the first lens group and the rear lens group. The zoom lens has, at a wide angle extremity thereof, a half angle of view of more than 60.degree., which constitutes a half angle of view of a fisheye lens.

Super wide angle zoom lens

Reflection-type compound optical elements include a substrate, an aspherical resin layer and a high reflectance layer. The substrate, the aspherical layer and the high reflectance layer are laminated in an optional order to form a laminate structure.

Reflection-type compound optical elements

An inner focus type telephoto zoom lens which includes a first lens group having a positive power, and a rear lens group of a variable power having a plurality of lens groups, located in this order from an object side. The first lens group includes a first sub-group of lenses which is not moved for focusing, and a second sub-group of movable positive lenses that are moved along an optical axis to for focusing.

Inner focus type telephoto zoom lens

A two-group zoom lens is provided which has a first lens group of negative power and a second lens group of positive power, located in this order from an object to be photographed. The first and second lens groups are moved relative to one another to provide various degrees of magnification. The first lens group includes a first lens of negative power, a second lens of negative power, and a third lens of positive power. The second lens group includes a fourth lens of positive power, a fifth lens of positive power, a sixth lens of negative power, and a seventh lens of positive power. The fifth lens is cemented to the sixth lens. The fifth and sixth lenses satisfy the following conditions: (a) 0.1&lt;n.sub.N -n.sub.P &lt;0.4; (b) -1.3&lt;r.sub.c /f.sub.2 &lt;-0.5; and (c) 0.6&lt;d.sub.1-2 /f.sub.w &lt;1.2; wherein, n.sub.P represents a refractive index of the fifth lens, n.sub.N represents a refractive index of the sixth lens, r.sub.c represents a radius of curvature of the cementing surface of the fifth and sixth lenses, f.sub.2 represents a focal length of the second lens group, d.sub.1-2 represents a distance between the first and second lens groups, and f.sub.w represents a focal length of the entire zoom lens at a wide angle extremity.

Two-group zoom lens

A telephoto zoom lens system is disclosed in which the wide-angle end starts with the middle telephoto range and in which focusing is done by means of a lighter focusing lens group than what is used in the method of focusing by advancing the front lens component and that only small aberrational variations occur even if zooming is done up to the closest focusing distance. The telephoto zoom lens system includes a front lens component and a rear lens component, said front lens component comprising a front lens group and having, in order from the object side, a positive first sub-group 1a and a positive second sub-group 1b and having an overall positive power. The first sub-group 1a is such that a negative meniscus lens having a convex surface directed towards the object is located closest to the image plane, and the rear lens component is located closer to the image plane than the front lens component and having a zooming capability, focusing for the object being effected by moving only the second sub-group 1b towards the object when it is positioned at near distance.

Telephoto zoom lens system

A zoom lens comprises at least four lens groups, including a negative first lens group, positive second lens group, negative third lens group and a positive fourth lens group. When the power is varied from wide angle to telescopic, the lens groups are moved such that the distances between the first and second lens groups and between the third and fourth lens groups are reduced. The distance between the second and third lens groups is increased, and an aperture disposed near the second lens group is moved together with the second lens group.

Zoom lens

A retro-focus wide-angle lens system having, in order from the object side, a negative power front group and a positive power rear group having a diaphragm stop. The front group comprises a positive first lens element and a negative meniscus second lens element having a convex surface directed towards the object. The rear group comprises a positive third lens element, a negative fourth lens element having an aspheric surface and a positive fifth lens element. The negative power of the fourth lens element increases toward the outer edge.

A large aperture, medium telephoto lens system is disclosed which is composed of a front group G.sub.F that comprises, in order from the object side, at least two positive lens elements having a strong convex surface directed toward the object and a negative lens having a strong concave surface directed toward the image and which has a positive overall refractive power, and a rear group G.sub.R with a surface S.sub.R1 which is the closest to the object being convex toward the object and which the a positive overall refractive power, with only the rear group G.sub.R being moved along the optical axis to perform focusing operations.

Large aperture, medium telephoto lens system

A telephoto zoom lens system featuring a zoom ratio on the order of 3 which uses an inexpensive optical material having a lens refractive index and which is compact in size can be attained. A first lens group I closest to the object side has a positive refractive power. The first lens group I includes a first negative maniscus lens element having a convex surface directed toward the object and a second positive lens element having a convex surface with a large curvature directed toward the object. A second lens group II having a negative refractive power is located on the image side of the first lens group I. A third lens group III having a positive refractive power is located on the image side of second lens group II. Lens group III includes a first lens unit IIIa having a positive refractive power and a second lens unit IIIb having a positive or negative refractive power. Zooming is performed by moving the three lens groups independently of one another along the optical axis. Focusing is performed by moving the first lens groups along the optical axis. Second lens group II preferably includes two negative lens elements and one positive lens element. Lens unit IIIa preferably includes two positive lens elements and one negative lens element while lens unit IIIb preferably includes a positive lens and a negative meniscus lens having a convex surface directed toward the image.

Growing community of inventors

Tokyo, Japan

Jun Hirakawa