Canon Kabushiki Kaisha

Kouji Oizumi

Yasuyuki Yamada

Hiroki Nakayama

Yasuhisa Sato

Nozomu Kitagishi

Takashi Matsushita

Takeshi Koyama

Keiji Ikemori

Yoshinori Itoh

Sadatoshi Takahashi

Shoichi Yamzaki

A varifocal lens is disclosed, comprising, from front to rear, a first lens unit of negative power, a second lens unit of positive power, and a third lens unit of negative power, all these lenses being moved along a common optical axis when the focal length of the entire lens system varies, wherein all the lens units each are constructed with either one lens, or two lenses, the total number of lenses being limited to 3 or 4, while still maintaining good optical performance.

Compact varifocal lens

A zoom lens comprising, from front to rear, a first lens unit of negative power, a second lens unit of positive power and a third lens unit of negative power, the second and third lens units being moved to effect zooming, and the third lens unit having its focal length f.sub.3 laid in the following range:

Compact zoom lens

An image stabilizing system includes a photographic lens device having a plurality of lens units, wherein for zooming at least one lens unit separation varies, a detecting circuit for detecting the jiggle of the system, and a drive device for driving at least one lens unit in a direction perpendicular to a photographic optical axis of the photographic lens device on the basis of an output of the detecting circuit to stabilize an image.

Optical system for stabilizing an image

A small-sized camera in which while the light emerging from a photographic lens having an optical axis parallel with a photosensitive plane is conducted by first and second mirrors to the photosensitive plane to form a photographic system, the first or second mirror is turned around a predetermined axis to conduct the light to an eyepiece lens to form a finder system. And, a structure of construction for efficiently removing the stray light of this camera is disclosed.

Small-sized camera

A distance measuring device has a light source for emitting a plurality of light beams in a plurality of directions, and a light receiving lens having a plurality of optical axes for receiving the plurality of light beams reflected from objects in said plurality of directions. Light receiving apparatus is provided for receiving the reflected light beams passing through said light receiving lens and providing an output corresponding to distances to the object. The light receiving lens has (1) a central portion with a thickness (D), a focal length f.sub.a, and a refractive index .phi..sub.A, and (2) a second portion adjacent said central portion. Surfaces of said central and second portions closest to said light receiving apparatus comprising one spherical surface having a refractive power .phi..sub.R. the central and second portions being disposed to satisfy the following conditions:

Automatic multi-point distance measuring device

A finder device is disclosed comprising a first lens group having a positive refractive power to form a first image, a second lens group having a positive refractive power to re-form the first image, and an eyepiece lens group having a positive refractive power to observe the image the second lens group forms, wherein zooming is performed by moving the first and second lens groups along respective different loci of motion from each other.

Variable magnification finder of real image type

A finder device capable of forming an erecting non-reverse image to be observed at either of the waist level and the eye level, wherein when used as the waist-level finder, the photographer, while taking his eye at a good distance from the finder, can observe the image of an object to be photographed.

Finder device

A camera having a photographic lens and an eyepiece lens for observing an image formed by the photographic lens, wherein when this camera is used as a telescope, the interval between the image and the eyepiece lens is shortened, while simultaneously changing the focal length of the eyepiece lens, so that the magnification of the finder is increased.

Camera having telescopic capability

A photographic optical device of this invention comprises: a master lens unit having a positive refractive power, determining a photographic optical path and moving along the optical axis to change magnification; a first auxiliary lens unit having a positive refractive power and being capable of being placed on and off the optical path; and a second auxiliary lens unit having a negative refractive power and being capable of being placed on and off the optical path. The first auxiliary lens unit is attached to an image-plane side of the master lens unit to form a photographic unit giving a low ratio of magnification. The second auxiliary lens unit is attached to an image-plane side of the master lens unit to form another photographic unit giving a high ratio of magnification. The first and second auxiliary lens units are placed outside of the optical path to form another photographic unit giving a middle ratio of magnification.

Photographic optical device with variable magnification

The disclosed variable magnification finder includes, from front to rear, a first lens unit of negative power, a second lens unit of positive power, a third lens unit of positive power, the first, second and third lens units constituting an objective lens of positive power, and an eyepiece of positive power. The first and second lens units form a finder image on a plane just in front of the third lens unit. The second lens unit is moved axially forward to increase the image magnification, while the shift of diopter of the finder is simultaneously compensated for by moving the first lens unit.

Finder of variable magnification

A changeover type variable magnification optical system whose focal length is changed by locating an auxiliary lens on the image side of a master lens assembly. The system satisfies following inequalities of:

Variable magnification optical system

A conversion lens for attachment to the rear of a master lens to increase the focal length of the entire system, includes a positive lens, and a negative lens positioned on the image side of the positive lens, wherein at least one of the lens surfaces of the positive lens and the negative lens is an aspherical surface.

Conversion lens releasably attached behind master lens

A view finder having, from front to rear, a first lens unit of negative power, a second lens unit of positive power and a third lens unit of negative power, the second lens unit being moved axially forward as the magnification varies from the smallest to the largest value, while the first lens unit is moved to compensate for the diopter shift resulting from the variation of the magnification.

View finder of variable magnification

A variable power finder having an objective lens of positive refracting power comprising a first lens unit of positive refracting power movable along an optical axis and a second lens unit releasably attached to the first lens unit in axial alignment, wherein a real image to be observed is formed by the objective lens.

Variable power finder

In the disclosed zoom lens, a positive front lens unit and a negative rear lens unit are moved forwardly axially in differential relation to vary the overall focal length from a minimum to a maximum value, while a positive middle lens unit is kept stationary during the variation of the focal length. A diaphragm determining the F-number is positioned at a fixed point between the front and rear lens units.

Growing community of inventors

Kanagawa, Japan

Kouji Oizumi