Abstract: A compact zoom lens comprising, from front to rear, a positive 1st group movable for focusing consisting of a positive doublet of negative and positive lenses and a positive singlet, a negative 2nd group movable for variation of magnification consisting of a negative singlet and a negative doublet of negative and positive lenses, a positive 3rd group movable for image shift compensation simultaneously with the second group consisting of a positive doublet of positive and negative lenses, and a relay lens of positive power consisting of 4th and 5th groups, the fourth consisting of at least one positive lens of forward convexity and a negative lens, and the fifth consisting of a negative meniscus lens of rearward convexity and a positive lens, the zoom lens satisfying the following conditions:0.7<.phi.4,5/.phi.4<0.85 (1)1.5<.phi.4s/.phi.4,5<2.2 (2)N4n>N4p (3)1.76<N5n<1.85 (4)30<.nu.5p<45 (5)where .phi.4,5 is the overall refractive power of the 4th and 5th groups; .phi.

Abstract: A telephoto objective lens consisting of a positive front lens group and a negative rear lens group which is divided into sub-groups, the rear one being movable for focusing and the front one remaining stationary, thereby the weight of the complete objective is minimized. As the front lens group consists of only one positive and only one negative lens element, since the provision for focusing is made at such lens, this objective lens tends to produce aberrations of which the spherical and comatic aberrations are particularly deteriorated. According to the invention, therefore, the frontmost surface and rearmost surface of the front lens group and the rearmost surfce of the movable sub-group are specified in radius of curvature to achieve good stability of correction of the aberrations throughout the focusing range.

Abstract: In the camera disclosed, a volume type diffraction device having an indicium recorded therein to be reproduced later, is sealed between transparent optical members and arranged in the finder optical path so that when illuminated by a light source at an oblique angle, the indicium is reproduced, represents photographic information to be displayed in the finder.

Abstract: The present invention relates to a large aperture zoom lens consisting of a positive focusing lens group, a negative variator, a negative compensator, an afocal lens group and an image forming lens in sequence from the object. The focusing lens group consists of a negative meniscus lens whose convex surface is directed toward the object, a bi-convex lens and a positive meniscus lens whose convex surface is directed toward the object, the variator of a negative meniscus lens whose convex surface is directed toward the object, the bi-concave lens and a positive lens cemented with each other, the compensator representing a negative lens of a bi-concave lens and a lens cemented with each other, the negative meniscus lens in the focusing lens group is distant from the bi-convex lens so as to form are air lens with weak divergence and the compensator is moved forwards and backwards at the same time with the movement of the variator for zooming.

Abstract: A method of designing a telephoto type zoom lens having a convergent front member movable for focusing and capable of providing focusing down to as short an object distance as 6.5 times the longest focal length to achieve good stabilization of correction of spherical aberration on adjustment of the other aberrations within predetermined limits throughout the extended focusing range even when zooming is effected to the telephoto settings. This is accomplished by means of the formula:F(Ao, Lo) = .phi..sup.3 h.sup.4 Ao(1-.lambda..sup.4 -4a.beta.+6a.sup.2 .beta..sup.2) + 4.phi..sup.2 h.sup.2 Lo(-.beta.+3a.beta..sup.2) - .beta.(.alpha.').sup.2 + .beta..sup.2 {2.phi.(3+Po) + 3.alpha.'.alpha.'}In the case of the telephoto type zoom lens comprising, in addition to such front component, a divergent second component or variator, a convergent or divergent third component or compensator and a convergent fourth component or relay lens,-0.25.ltoreq.F(Ao, Lo).ltoreq.0.25is found as acceptable.

Abstract: A zoom lens system having a range in the order of 1:9 with a relative aperture of 1:1.4, including a variable afocal front attachment and a basic objective which is designed to improve the Petzval sum with front and rear groups each consisting of three lens elements of positive, positive and negative powers in this order from the front by fulfilling the following relationships with its individual focal length Fr: ##EQU1## wherein Ff is the focal length of the front group; r4 is the radius of curvature of the rear surface of the second positive lens in the front group; r5 is the radius of curvature of the front surface of the negative lens in the front group; r8 and r10 are the radii of curvature of the rear surfaces of the first and second positive lenses in the rear group respectively; and r11 is the radius of curvature of the front surface of the negative lens in the rear group.

Abstract: 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.

Abstract: A zoom lens having a focal length range of about 1:9.5 with a relative aperture of 1:1.4 and whose minimum focal length is made shorter than has heretofore been possible to correspond to an image angle of 56.degree. or more, while good stability of aberration correction is maintained throughout the extended zooming range at the increased relative aperture with limitation of the overall dimensions to a minimum. The lens is suitable for cine cameras of small size and includes a positive first group of four lens elements movable for focusing, negative second and negative third groups axially movable to effect zooming, a positive fourth group acting in afocal manner, and a positive fifth group having an image forming function, the first, fourth and fifth groups being stationary during zooming.

Abstract: A camera according to this invention includes a diffracting means disposed in the optical path of the object image forming light for a finder. The diffracting means is illuminated by a light source also provided within the body of the camera so as to exit the diffracted light toward the object side. A person who stands on the object side as an object can ascertain whether or not he is within the area of the object field to be photographed by the camera. Also, in taking a picture of himself with a camera mounted on a tripod using a self-timer, he can, while standing on the object side, obtain information about the self-timer through a photographic lens. According to one preferred embodiment of the invention, as the diffracting means, there is used a volume type phase diffracting means to avoid any adverse effect of the diffracting means on the object image forming light in which the diffracting means is placed.

Abstract: 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.

Abstract: A zoom lens comprising, as viewed from the side of a photographing object, a first lens group, which is positive and is provided for focusing, including a positive lens formed by joining a negative lens and a positive lens together and a positive meniscus lens; a second lens group, which is negative and is provided for variation, including a negative lens and another negative lens formed by joining a negative lens and a positive lens together; a third lens group, which is provided for compensation, including a positive lens formed by joining a negative lens and a positive lens together; a fourth lens group which is positive and is provided for image formation; and a fifth lens group which is weakly negative, the third lens group drawing a concave locus toward the object side as the second lens group moves in the direction of an optical axis. The fourth lens group is composed of two positive meniscus lenses closedly adjacent to each other and a biconcave lens disposed apart from these meniscus lenses.