Canon Kabushiki Kaisha

Akira Tajima

Sadahiko Tsuji

Naoto Kawamura

Keiji Ikemori

Hiroshi Furukawa

Yasuhisa Sato

Yukiharu Ono

Kazuo Tanaka

Kazuya Hosoe

Nozomu Kitagishi

Toshikazu Ichiyanagi

Setsuo Minami

Noritsugu Hirata

Sadatoshi Takahashi

Muneharu Sugiura

Ryusho Hirose

Kazuo Ishikawa

Tomoshi Takigawa

Toshiaki Asano

Shin Yamaguchi

Keiichi Sakaguchi

Yujiro Agari

Katumi Tanaka

An ultrasmall size zoom lens comprising two lens groups of which the first has a positive refractive power and the second has a negative refractive power, the first lens group including at least two positive lenses and at least one negative lens, the second group including at least one positive lens and at least one negative lens, and the axial air separation between the first and the second lens groups being variable to effect zooming.

Ultrasmall size zoom lens

Focusing optics placed behind the zooms optics of a zoom arrangement are focused by computing the necessary focusing movement in response to the output of a focal length detector and an object distance detector. Comparison is made to the actual position of the focusing optics.

Focus apparatus for zoom lens system with distance detection

A zoom objective comprising four lens groups of which the first three lens groups counting from the object side are movable for zooming, whereby the refractive powers and the conditions of zooming movement of the aforesaid three lens groups are properly specified so as to improve the compactness while still maintaining good correction of aberrations.

Zoom objective

A focusing device in which, in a condition in which the focus detecting operation is impossible, when the set focus position of the picture-taking lens is on the short distance focus side, the lens is forcibly shifted to the long distance focus side and when the set focus position is on the long distance focus side, the lens is shifted to the short distance focus side, whereby the device can quickly get away from the condition in which the focus detecting operation is impossible.

Focusing device for a camera

An optical low-pass filter is comprized of micro stripe prisms arranged on the surface of a transparent member. A transmissive medium which is of different refractive index from that of air is used to fill the grooves of the microprisms to permit the arrangement to have micro stripe prisms with a large vertex angle.

Optical low-pass filter

The wide angle zoom lens disclosed includes, from front to rear, a negative first lens group and a positive second lens group, both of which are moved axially in variable relation to each other to effect a change in the image magnification. The first lens group includes, front to rear, a first lens with a rear surface of strong negative refractive power, a second lens of convex curvature towards the front with a focal length having an absolute value not less than 30 times the shortest focal length of the entire system and with at least one of the surfaces thereof aspherical and a positive meniscus 3rd lens of forward convexity. According to one embodiment, the second lens is made of glass and according to another, of plastic.

Wide angle zoom lens

A zoom lens comprising, from front to rear, a first lens group of negative power, and a second lens group of positive power with the axial air separation therebetween being variable to effect zooming. The first lens group includes at least one negative lens element and one positive lens element, and the negative lens element has its one surface configured to an aspheric shape, and is made of a plastic material. The bulk and size of the lens system is minimized even though the aberrations are well corrected.

Zoom lens

The focal length at the telephoto end of a zoom lens is increased by making the magnification of the system .beta. with auxiliary focusing means while the ordinary focusing means of the zoom lens system is focused on infinity. An attachment lens having a focal length fA is provided in front of the zoom lens system in such a manner that the composite lens system is focused on infinity. The product fA .beta. of the magnification .beta. and the focal length fA of the attachment lens is longer than the focal length of the zoom lens.

Method to increase focal distance at telephotographic side of a zoom

The disclosed two-group wide-image-angle zoom lens is zoomed by changing the distance between the front and the rear group. The front group exhibits a negative refracting power and includes a first positive lens, a second negative lens concave toward the image end, a third positive lens, a fourth negative lens concave toward the image end, and a fifth positive image lens convex toward the object end, all in sequence; the rear group is closer to the image end than the front group, exhibits a positive refracting power, and includes a first positive sub-group, a second positive sub-group, a third negative sub-group, and a fourth positive sub-group.

Two group type zoom lens with wide image angle

An optical system for forming a view-finder image in combination with an image of exposure condition indicia as applied to a cinematographic camera includes a first image plane at which a focusing screen lies with the exposure condition indicia located at a desired large distance from the finder field of view, and a prism positioned ahead of a second image plane at which both the images are erected, and oriented so that the image of the indicia can be seen immediately adjacent the finder field of view by a photographer looking through an ocular of the system.

Photographic camera with an image of exposure condition indicia visible

A light meter arrangement for a camera having a zoom objective and a view finder. A beam splitter is arranged between the zoom control lens assembly and the relay lens to split off a fraction of the beam of light coming from the assembly and to direct the fraction of afocal form to the view finder. In order to deflect an integral marginal portion of the view finder light beam to a light-sensitive element, there is provided a single prismatic entity having an entrance face positioned adjacent the exit face of the beam splitter. This entity is constructed to have a number of total reflection surfaces arranged to function as a condenser for the light rays passing therethrough.

Light metering system in a camera

In the disclosed camera, an SLR viewfinder displays exposure conditions by means of a translucent indicia carrier adjacent the focusing plate which defines the field of view of the finder. A light source illuminates the translucent indicia carrier and its light is passed by suitable lenses to a viewer. Ghost images of the indicia indications, which might be caused by indicia image light beams being internally reflected by the plate and lenses, are effectively eliminated by an optical deflector that orients light from the source along an optical axis parallel to or away from the light passing through the focusing plate's field of view. According to one embodiment of the invention, the light deflector is a prism. According to another, it is a mirror.

Photographic camera with an information indicating finder

A zoom lens system comprising from front to rear a first lens group of negative power and a second lens group of positive power with the axial separation therebetween being variable for zooming purposes. The first lens group is provided with a non-spherical surface to achieve minimization of the overall dimensions of the complete system without causing any decrease in the extent to which the corrections of various aberrations are maintained throughout the zooming range irrespective of a great increase in the photographable range extended toward the wide angle side.

Zoom lens system

In a zoom lens consisting of a first lens group having a negative refractive power and a second lens group having a positive refractive power with the air separation between the first and second groups being variable for zooming, there are provided two non-spherical surfaces positioned respectively in the first lens group and on the image side of a diaphragm in the second lens group at optional locations to prevent deterioration of aberrations which occurs when the image angle of the zoom lens is increased.

In a variable focus objective an axial air space between a negative front lens and a positive rear lens component is variable for zooming. The first component is movable for focusing independently of the rear component and provided with a variable air space defined therein to facilitate focusing down to short object distances while preserving high grade imagery for close objects throughout the zooming range and assuring a good uniformity of image quality throughout the entire image region even at the full open aperture.

Growing community of inventors

Kawasaki, Japan

Akira Tajima