Abstract: An optical pickup apparatus for at least two kinds of optical information recording media, comprises a first light source; a second light source; an optical converging system; and a photo detector. An optical element of the optical converging system comprises a first region including an optical axis and a second region adjoining the first region and locating at the outside of the first region, the first region is a reflective surface and the second region is a diffractive surface. When a first light flux passes through the second region, the light amount of n-th order diffracted ray of the first light flux is larger than that of any other order diffracted ray of the first light flux, and when a second light flux passes through the second region of the optical element, the light amount of n-th order diffracted ray of the second light flux is larger than that of any other order diffracted ray of the second light flux, where n is an integer except 0.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: A zoom lens includes: a first lens group having positive refracting power; and a second lens group provided on an image side of the first lens group, having negative refracting power. The zoom lens has a variable power ratio of not less than 2.5 and a field angle of not less than 70° at a wide angle end, and a magnification of the zoom lens is changed by changing a distance between the first lens group and the second lens group, and further the following conditions are satisfied, 1.25≦Tw/Tt≦1.8 0.6≦fFc/fw≦0.9 where Tw represents a telephoto ratio at a wide angle end of the zoom lens, Tt represents a telephoto ratio at a telephoto end of the zoom lens, fw represents a focal length of the zoom lens at the wide angle end, and fFc represents a focal length of the first lens group.

Abstract: A camera provided with a triplet type lens for taking a photograph in which the first lens having a positive refracting power, the second lens having a negative refracting power and the third lens having a positive refracting power are arranged in that order from the photographic object side of the camera, and a diaphragm is located at the rear of the triplet type lens. In this camera, the longitudinal direction of the picture-taking image plane is curved onto the photographic object side, and the triplet type lens satisfy: 0.41.ltoreq.P.D.ltoreq.0.98 where P is the Petzval's Stun of the triplet type lens and D is the length of the diagonal line of the image plane.

Abstract: A display device in a real image type viewfinder includes an optical member having an image formation surface thereon, which is provided between an objective lens and an eyepiece. An object image is formed by the objective lens on the image formation surface. A display section in a view field frame to display the view field frame is provided when an inclined surface portion is formed in a direction in which a peripheral portion of the image formation surface of the optical member is protruded with respect to the image formation surface.

Abstract: An Albada type inverted Galileo finder which is suitable foruse with a compace lens shutter camera, which is small in size, and which is visible without occurrence of any ghost not only in an object but a finder frame.If lenses are disposed in order of negative, positive and positive from the side of an object and a reflecting surface of an Albada system is a surface on the side of the object of a positive lens, a finder which involves no ghost and is advantageous for correction of aberrations can be obtained. Furthermore, if the on-the-axis thickness of each lens is restricted to thereby provide a plastic lens, precision of molding can be improved.

Abstract: A zoom lens is known which has a first lens group having a negative refracting power and a second lens group having a positive refracting power arranged from an object side, a spacing between both the lens groups being varied to thereby vary magnification (variable power). In order to make such zoom lens compact, the refracting power of the negative lens group is intensified and the negative refracting power is arranged in a portion at the rear of the positive lens group. The portion in the positive lens group is composed of a set of positive and negative lenses, and at least one surface of the lenses is made to be an aspherical surface to correct aberrations.