Abstract: A zoom lens has, in succession from the object side, a first lens unit of positive refractive power fixed during focal length change, a second lens unit of negative refractive power for focal length change, a third lens unit of negative refractive power for correcting the fluctuation of the image plane resulting from focal length change, and a fixed fourth lens unit of positive refractive power, and a thin layer of resin satisfying a predetermined condition is provided on at least one lens surface of the first lens unit.

Abstract: An ink conducting core for supplying ink from an ink container to a pen point is formed with an exposing recess in the vicinity of a connecting portion of the ink conducting core with a middle core. With this, even when outside impact etc. causes air bubbles to enter the ink conducting core, the bubbles may be ejected readily through the exposing recess whereby smooth ink supply can be secured all the time. An annular groove and a small diameter portion is provided in the rear part of an ink conducting core. An ink retainer having a through-hole through which the ink conducting core is fitted is constructed such that the through-hole has a small diameter portion in the rear end thereof. The ink conducting core is fitted to the ink retainer with the side walls of the annular groove engaging the small diameter portion in the rear end of the through-hole. As a result, it is possible to securely restrict back-and-forth movement of the ink conducting core due to impact etc.

Abstract: A zoom lens is disclosed comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a flare cut stop for cutting a lower marginal ray of an off-axial bundle of rays for a maximum image height, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power, wherein the second and third lens units move axially to effect zooming, while either varying the aperture diameter of the flare cut stop or axially moving the flare cut stop to thereby cut the harmful rays for good optical performance.

Abstract: A zoom lens comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power for varying the focal length, a third lens unit of positive or negative refractive power for compensating for the image shift with zooming, an aperture stop and a fourth lens unit having the image forming function and stationary during zooming, wherein the first lens unit has a front lens sub-unit of negative refractive power, a first lens sub-unit of positive refractive power and a second lens sub-unit of positive refractive power, and wherein during focusing from an infinitely distant object to an object at the minimum distance, at least the first and second lens sub-units are axially moved.

Abstract: A high range zoom lens is disclosed, comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive or negative refractive power and a fourth lens unit of positive refractive power, the second and third lens units being movable for zooming, wherein an aspheric surface is introduced into the second or third lens unit at a specified location so that the variation of aberrations with zooming is as far reduced for high performance as possible.

Abstract: A high range zoom lens is disclosed, comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive or negative refractive power and a fourth lens unit of positive refractive power, the second and third lens units being movable for zooming, wherein an aspheric surface is introduced into the second or third lens unit at a specified location so that the variation of aberrations with zooming is as far reduced for high performance as possible.

Abstract: The present invention relates to an apparatus for controlling the lens position of a zoom lens. The zoom lens comprises a plurality of lens units movable along the optical axis for zooming, a focal length setting unit for setting the focal length of the zoom lens, an object distance setting unit for setting an object distance, a store containing a plurality of inherent coefficients and an arithmetic logic unit which specifies focal length information and object distance information as variables, and uses the coefficients in calculating a position to which a lens unit should move.

Abstract: A zoom lens comprising, from front to rear, a focusing lens group, a variator lens group, a compensator lens group and a relay lens group, the relay lens group consisting of a front part and a rear part with a longest air spacing therebetween, and the rear part including a first movable lens component arranged upon setting of macro photography made to move along an optical axis, and a second movable lens component arranged upon setting of tracking adjustment made to move along the optical axis.

Abstract: A zoom lens is disclosed comprising a front lens unit, an intermediate lens unit having two lens sub-units with their axial separation varying for zooming purposes, and a rear lens unit, wherein at the wide-angle end, focusing is performed by moving at least the rear lens unit, and, at the telephoto end, focusing is performed by moving the intermediate lens unit and the rear lens unit, whereby the amount of focusing movement of the intermediate lens unit from an infinitely distant object to an object at a certain short distance is greater at the telephoto end than at the wide-angled end.

Abstract: A zoom lens capable of changing the range of variable focal length to another limit, comprising, from front to rear, a zoom section including a variator and a compensator arranged upon zooming movement to vary the focal length in a predetermined range, a diaphragm, and a relay lens section receptive of the afocal light beam from the zoom section to form an image and having a front lens unit and a rear lens unit, the front lens unit being provided with a fixed sub-unit and an interchangeable sub-unit in this order from the front, wherein the interchangeable sub-unit is removed to create a space between the fixed sub-unit and the rear lens unit, into which a range changing lens unit is then inserted, so that the range of variable focal length is changed.

Abstract: A projection lens system comprises a first group of lenses having at least one variable spacing for correcting aberration, and a second group of lenses having a variable spacing for focusing with the lens located closest to an image being fixed. It corrects variation of aberration and allows variable projection magnification.

Abstract: A projection lens for enlarging and projecting a television image on a screen including: a first lens L1 having a positive refracting power; a second lens L2 having a positive refracting power and a convex surface which is located at the side of L2 nearer to the image and which has a larger curvature than that at the side of L2 nearer to the screen; a third lens L3 which consists of a meniscus lens having a concave surface located at the side of L3 nearer to the image; and a fourth lens L4 having a concave surface which is located at the side of L4 nearer to the screen and which has a larger curvature than that at the side of L4 nearer to the image. The lenses L1, L2, L3 and L4 are arranged from the side of the screen in the order named. The combined refracting power of the second and third lenses is larger than that of the first lens. At least one nonspherical surface is provided in the first lens, and at least one nonspherical surface is provided in the second, third and fourth lenses.

Abstract: A television camera is provided with a color resolving optical system for color resolution and for forming a plurality of optical paths, the color resolving optical system having at least one dichroic film, a plurality of image pick-up tubes disposed on the optical paths for receiving the image of an object to be photographed, and an illuminating device emitting a plurality of illuminating lights of a predetermined wavelength range and provided with an adjuster for adjusting the quantity of light of at least one of said illuminating lights. The wavelength band width of said illuminating lights is narrower than the wavelength band width color-resolved by the color resolving optical system and/or the positions at which said illuminating lights are emitted differ from one another, whereby color shading of the image pick-up tubes is eliminated.