Abstract: A zoom lens system is disclosed in which a high zoom ratio of 2.5 or more, that is short in the overall lens length, that is composed of a smaller number of lens elements, that will experience less deterioration in performance due to manufacturing or assembly errors or less focus shift due to temperature or humidity changes, and which hence is suitable for use with a compact camera.

Abstract: A cemented plastic lens is formed of two plastic lenses made of dissimilar synthetic resin materials having different coefficients of thermal expansion. The lenses have mating surfaces that have macroscopically the same curvature, and the mating surfaces are bonded together with a soft adhesive that is capable of elastic deformation by itself in a hardened state and that has the ability to attenuate the stress that will develop at the cemented interface due to the thermal expansion mismatch.

Abstract: An imaging lens system is disclosed which comprises a focusing lens and a correcting lens which has aspherical surfaces on both side. Usually, the focusing lens if located on the object side but the correcting lens may be disposed on the object side.

Abstract: An automatic focusing method is disclosed with which a plurality of selected objects can be held within the focusing range of the photographing lens of a camera. For each of object for which it is desired to keep within the focusing range, a focusing detection operation is carried out to provide defocusing data for the object. A weighted mean value of the defocusing data is employed as a common focal position.

Abstract: The improved reading zoom lens system includes, in order from the object side, a front group that has a positive power and that is of a four-unit-six-element composition and a rear group that has a positive power and that is composed of two elements, which lens system is capable of zooming by changing the distance between the front and rear groups and satisfies the following conditions (a) to (c):(a) 0.90<fL/fF<1.10(b) 0.09<fF/fR<0.35(c) 3.0<(dL-dS)/(fL-fS)<9.5where fL: the focal length of the overall system at the highest magnification;fS: the focal length of the overall system at the lowest magnification;fF: the focal length of the front group;fR: the focal length of the rear group;dL: the variable distance at the highest magnification; anddS: the variable distance at the lowest magnification.

Abstract: A signal generator 51 supplies a switching signal to a color difference signal output switch 44 in response to a line index signal LI and/or a horizontal synchronizing signal HD, thus avoiding the outputting of a signal obtained by adding two color difference signals.

Abstract: 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.

Abstract: A real image type view finder comprising at least one cemented lenses. Of the lens components constituting the cemented lens, a lens component is made of resin. The lens component may be made of material of high transmittance to ultraviolet rays.

Abstract: A four-group zoom lens system that achieves satisfactory brightness and zoom ratio for practical applications and yet is compact and can be manufactured at low cost. The lens system includes in order from the object to the image side, a positive first lens group, a negative second lens group, a negative third lens group, and a positive fourth lens group composed of a positive front lens unit (4.sub.f) and a positive rear lens unit (4.sub.r), the first to third lens groups being capable of moving independently of one another along the optical axis. The front lens unit (4.sub.f) includes in order from the object to the image side, a positive first lens element (4.sub.1) having a convex surface on the image side, a positive second lens element (4.sub.2), a positive third lens element (4.sub.1) having a convex surface on the object side and a negative fourth lens element (4.sub.4) having a concave surface on the object side. The rear lens unit (4.sub.

Abstract: A zoo comprises, in order from the object side, a first lens group having a positive refractive power that moves along the optical axis for focusing, a second lens group having a negative refractive power that moves along the optical axis for zooming, a third lens group having a negative refractive power that moves along the optical axis for compensating for the image plane that varies upon zooming, and a fixed, imaging fourth lens group having a positive refractive power. The fourth lens group has an aperture and comprises a first sub-group having a positive refractive power and a second sub-group having a positive refractive power, which fourth lens group further satisfies certain conditions.

Abstract: An optical pickup apparatus includes a lens holder, a focusing coil mounted on the lens holder and passing through a gap between first and second yoke portions, and a tracking coil mounted on the lens holder in such a manner that it does not pass through the gap but passes adjacent a third yoke portion.