Abstract: A retro focus lens having three lens groups arranged, in order from the longer conjugate length side of the lens, as follows: a negative first lens group G.sub.1, a positive second lens group G.sub.2, and a positive third lens group G.sub.3. The first group G.sub.1 includes, in order from the longer conjugate length side of the lens, a first lens element L.sub.1 of small positive refractive power and made of plastic with an aspherical surface, a second lens element L.sub.2 of negative refractive power that is made of glass and has a concave surface facing the shorter conjugate length side of the lens, and a third lens element L.sub.3 of negative refractive power with a concave surface facing the shorter conjugate length side of the lens, there being no additional lens elements between the first lens element L.sub.1 and the third lens element L.sub.3.

Abstract: A projection lens which has a wide angle view, a short projection distance and telecentricity, and in which the projection can be performed with high contrast, various aberrations such as a distortion aberration are reduced and the optical path is converted by providing a first lens group having negative refractive power and second and third lens groups having positive refractive power are arranged from a longer conjugate side. Representing a back focus at a projection distance of an infinite point by BF; the composite focus distance of the entire system by F; a center distance between said first lens group and said second lens group by GD1; the composite focus distance of said first lens group by F1; the composite focus distance of said second lens group and said third lens group by F23; and the center distance between said second lens group and said third lens group by GD2, the following relationships are satisfied:[2.8<BF/F],[3.0<GD1/F<4.50],[0.40<-F1/F23<0.48],and[0.40<GD2/F23<0.8].

Abstract: An image is picked up by a camera comprising a fisheye lens having a relationship of h=n.multidot.f.multidot.tan(.theta./m), wherein h is the height of an image of a subject at a certain point, f is the focal distance of the fisheye lens, .theta. is a field angle, m has a value of 1.6.ltoreq.m.ltoreq.3, and n has a value of m-0.4.ltoreq.n.ltoreq.m+0.4, and the image data of which is output from the camera, is converted into a plane image by an image data processing unit, and this converted image is then output to a monitor unit. Preferably, n and m both equal 2.

Abstract: A close-up photographing lens (10) having a long back focus and a large aperture, thus making the lens suitable for use with high-performance electronic imaging equipment. The lens comprises, objectwise to imagewise, a first lens group (G1) having positive refractive power, a second lens group (G2) having positive refractive power, and a relay optical system (GL) having positive refractive power. The relay optical system includes a third lens group (GLN) having negative refractive power and a fourth lens group (GLP) having positive refractive power. The first lens group and the second lens group are separated by an axial air space (D12) and move objectwise on different trajectories (16,18) when changing focus from an infinite focus state to a most close-up focus state. The axial air space is narrower in the most close-up focus state than in the infinite focus state. The lens preferably satisfies at least one of a number of design conditions.

Abstract: A projection optical system includes, in order from a first conjugate point side of longer distance to a second conjugate point side of shorter distance, a first lens unit in which negative lenses included therein are larger in number than positive lenses included therein, and a second lens unit in which positive lenses included therein are larger in number than negative lenses included therein, wherein design parameters are determined such that an off-axial principal ray intersects an optical axis at a point between the first lens unit and the second lens unit and telecentricity is made on the second conjugate point side, and wherein the second lens unit includes, in order from the second conjugate point side, a negative lens of meniscus form convex toward the second conjugate point side and a positive lens whose both surfaces are convex.

Abstract: A wide-angle lens system which has a long back focal length comprising a first lens unit having a negative power, a second lens unit having a positive power and a third lens unit having a positive power: the first lens unit being composed of a 1-1 positive lens unit which is composed only of a positive lens component and a 1-2 negative lens unit which is composed only of negative lens components, the third lens unit being composed of a 3-1 subunit which comprises at least a negative lens component and a 3-2 positive subunit which comprises at least a negative lens component, the 3-1 subunit being composed of a first negative lens component and a second positive lens component, and the 3-2 subunit being composed of a third negative lens component and a fourth positive lens component.

Abstract: A wide-angle lens has a three-group configuration in which a plastic aspherical lens is used in the first lens group on the enlargement side, and predetermined conditional expressions concerning focal lengths of individual lenses constituting the first lens group are satisfied, whereby image quality is restrained from deteriorating due to changes in temperature, and a telecentric characteristic is attained such that no vignetting occurs in marginal luminous fluxes, thus making various kinds of aberration favorable and allowing the cost to be cut down. The first lens group G.sub.1 disposed on the enlargement side has a three-lens configuration in which the first lens L.sub.1 on the enlargement side and the third lens L.sub.3 on the reduction side are constituted by a plastic aspherical lens having a negative refracting power and a plastic aspherical lens having a positive refracting power, respectively. Letting the focal length of the first lens group G.sub.1 be F.sub.

Abstract: Lens systems for wide band infrared camera having a bandwidth of 1-5 .mu.m with a low f-number and 100% cold stop efficiency.

Abstract: In a large-aperture lens for low-illuminance imaging, a Gauss type lens configuration is employed, and a negative lens having a predetermined refracting power is inserted in front of the front-side cemented lens, whereby back focus is secured while compactness is attained, without using an aspherical lens. Successively disposed from the object side are a biconvex lens L.sub.1, a positive meniscus lens L.sub.2 having a convex surface directed onto the object side, a negative lens L.sub.3 having a concave surface with a stronger curvature directed onto the image side, a positive meniscus lens L.sub.4 (cemented with lens L.sub.5) having a convex surface directed onto the object side, a negative meniscus lens L.sub.5 having a concave surface directed onto the image side, a biconcave lens L.sub.6 (cemented with lens L.sub.7) having a surface with a stronger curvature directed onto the object side, biconvex lenses L.sub.7 and L.sub.

Abstract: A wide-angle lens with an image stabilizing function comprises, from a front, object side to a rear, image side, a lens group GF with negative refractive power; a lens group GL with positive refractive power, wherein the back focal length is longer than the focal length of the entire optical system and overall refractive power is positive and wherein a partial lens group GLP having positive refractive power out of the lens group GL comprises at least a positive meniscus lens with the convex surface facing the image side and a biconvex lens; and a displacement device provided to reduce vibration by causing rotative motion of the partial lens group GLP about a point on the optical axis on the object side which is separated by a predetermined distance from a surface of the partial lens group GLP closest to the image side, wherein the focal length fLP of the partial lens group GLP and the focal length f of the whole lens system at infinite objective distance satisfy 0.3<fLP/f<5.0.

Abstract: In an image forming optical lens system comprising in order from the object end a first lens group of at least two components, a second lens group which has a positive focal length and comprises in order from the object end a first component of positive power, a second component of negative power and a third component of positive power, and a third lens group of at least one component, the components of the lens system are made of at least two different kinds of materials having differences in dispersion of 0.0055 at the greatest from one another and the first to third components of the second lens group are made of materials different in dispersion from one another.

Abstract: An offset reverse telephoto projection lens that is telecentric in modulator space and has an air equivalent back focal distance of at least 3.3 inches and preferably at least 4.0 inches. The lens comprising, from the image side, a first objective lens group 408 having a negative power and a second telecentric lens group having a positive power. The second telecentric lens group 410 is telecentric in object space such that the image of the aperture is focused at infinity and light converges on the object plane perpendicular to the axis of the lens. Embodiments of the lens have a back focal distance to effective focal length ratio of at least 0.86:1, preferably at least 1.2:1, more preferably at least 1.3:1, still more preferably at least 4.08:1, and most preferably 5.0:1. The embodiments described have a field of view between 14 degrees and 73 degrees, have throw ratios of 1.2:1 to 7:1, and an overall length ranging from less than 5 inches to 12.5 inches.

Abstract: A wide angle lens is made of three groups so as to satisfy a predetermined conditional expression concerning abbe number, thereby making it telecentric and yielding no eclipse in its peripheral luminous flux. Also, an apparatus accommodating it is made compact as a whole. This wide angle lens comprises, arranged in the following order from the screen side toward the liquid crystal side, a first lens group composed of a concave lens (L1), whose concave surface having a large radius of curvature is directed toward a smaller conjugate side (liquid crystal panel), and a convex lens (L2); a second lens group composed of one concave lens (L3) and two convex lenses (L4) and (L5); and a third lens group composed of a Fresnel lens (L6) which is disposed near a liquid crystal panel (L7; 4). The abbe number .nu. 1 of the lens L1 which is the concave lens in the first lens group is 57.8, whereas the abbe number .nu. 2 of the lens (L3) which is the concave lens in the second lens group is 25.

Abstract: The invention proves a compact and simple wide-angle lens system composed of a reduced number of lenses and having high productivity, which is well suited for use on digital cameras, while making sure of the space necessary for edge, and middle thicknesses, and constructing the system and, at the same time, having a given back focus and exit pupil position, and sufficient image-forming capability, and which comprises two lens groups or, in order from the object side thereof, a negative lens group GN and a positive lens group GP with an aperture stop D midway between them and a lens located nearest to the object side thereof being defined by a positive lens, said positive lens conforming to three conditions in terms of focal length, shape factor, and ensuring sufficient edge thickness.

Abstract: A cluster lens for imaging a transparency onto an image plane comprises a plurality of lenses which simultaneously have a field of view sufficient to include the transparency. All of the lenses image simultaneously. At least two of these lenses have different magnifications. The lenses are located in a spaced relationship to each other so that that not one of these lenses encroaches upon that section of the field of view of another lens that is used to image the transparency onto the image plane.

Abstract: An apochromatic wide-angle objective has an improved correction of transverse chromatic aberration while at the same providing a high correction of other errors. These corrections are obtained utilizing long-crown and short-flint glasses.

Abstract: A super wide-angle fast lens system includes a front lens group having a negative power, a diaphragm and a rear lens group having a positive power. The front lens group consists of a first sub-lens group having a negative power and a second sub-lens group having a negative power which is spaced from the first sub-lens group by a maximum distance. The lens system satisfies the following relationships:-0.5<f/f.sub.F <-0.2,-0.2<f/f.sub.1a <-0.07,3<d.sub.ab /f<7, and10<.SIGMA.d.sub.F+S /f<15,wherein "f" represents the focal length of the whole lens system, "f.sub.F " represents the focal length of the front lens group, "f.sub.1a " represents the focal length of the first sub-lens group, "d.sub.ab " represents the distance between the first sub-lens group and the second sub-lens group, and ".SIGMA.d.sub.F+S " represents the sum of the thickness of the front lens group and the distance between the front and rear lens groups.

Abstract: A retrofocus type wide-angle lens for achieving a highly stable imaging performance and a reduction in spherical aberrations, astigmatism, and coma, while allowing for a large aperture and a large wide angle of view. The retrofocus type wide-angle lens has, in the following order from an object side, a first lens group having a negative refracting power and being fixed in a focusing operation and a second lens group having a positive refracting power and being moved in the focusing operation. The first lens group has, in the following order from the object side, a first unit with a negative refracting power and a second unit having a positive refracting power. The second lens group has, in the following order from the object side, a first unit with a negative refracting power, a second unit with a positive refracting power, a third unit with a negative refracting power and a fourth unit with a positive refracting power.

Abstract: The present invention provides a photographic lens system capable of close-up photography in which various aberrations such as spherical aberration and coma, and curvature of field are concurrently corrected in a well-balanced state and which is relatively bright as expressed by an F-number of about 2.8, and is characterized by comprising a first lens group G.sub.1 which includes a front sub-group G.sub.1F having positive refracting power and a rear sub-group G.sub.1R having negative refracting power and has positive refracting power in its entirety, a second lens group G.sub.2 having positive refracting power in its entirety, and a third lens group G.sub.3 having positive refracting power in its entirety, the lens of the front sub-group G.sub.1F nearest to the image side being concave on the image side and the lens of the rear sub-group G.sub.

Abstract: An optical apparatus that enables an object at a first location to be viewed from a second remote location. The optical apparatus includes at least one objective lens assembly that views the object at the first location. The objective lens assembly focuses the viewed image onto the input plane of an image conduit. The fiber optic conduit propagates the image to the second remote location, wherein the image is projected from the image conduit onto the back surface of a substantially transparent planar member. The back surface of the planar member is not highly polished. As a result, the image projected onto the back surface does not pass directly through the planar member. The reflections caused by the unpolished nature of the surface allow the image to be viewed on the back surface of the planar member through the body of the planar member.

Abstract: A wide angle lens system comprises a front lens group and a rear lens group having positive refractive power. The front lens group includes in the order from the object side, a negative meniscus lens component having a convex surface facing the object side, a cemented lens component having a negative lens element and a positive lens element and a convex cemented surface facing the object side. The rear lens group includes a cemented lens component having a positive lens element and a negative lens element and a convex surface facing the object side. The rear lens group is moved toward the object side for focusing operation from the infinite object distance to the shortest object distance.

Abstract: A wide-angle lens system comprising, in order from the object side, a front unit, a stop and a rear unit: the front unit comprising, in order from the object side, a first lens unit which comprises a plurality of lens components including a positive lens component and has a negative refractive power as a whole, a negative lens component having a concave surface on the object side and a cemented lens component; and the rear unit comprising a negative lens component disposed on the side of the stop and at least two positive lens components. This wide-angle lens system has sufficiently corrected aberrations, in particular, negative distortion, curvature of field and sagittal coma.

Abstract: An inverse telescopic wide angle lens comprises a diaphragm; a front lens group of an integral positive or negative refractive power, positioned in the object side in front of the diaphragm and having a first lens group of a negative refractive power including a negative lens of which an image-side air-contacting surface is formed as an aspherical surface concave to the image side, and a second lens group of a positive refractive power positioned between the first lens group and the diaphragm; and a rear lens group of an integral positive refractive power, positioned behind the diaphragm and having plural lenses.

Abstract: A fast ultra-wide angle lens system is provided which includes a front lens group having a negative power, a diaphragm, and a rear lens group having a positive power, arranged in this order from a side of an object to be photographed. The lens system satisfies the following conditions:-0.5<f/f.sub.F <-0.2; (1)7.0<.SIGMA.d.sub.F+S /f<12.0; and (2)5.0<.SIGMA.d.sub.R /f<10.0, (3)wherein f represents a focal length of the entire lens system, f.sub.F represents a focal length of the front lens group, .SIGMA.d.sub.F+S represents a sum of the length of the front lens group and a distance between the front lens group and the rear lens group, and .SIGMA.d.sub.R represents a length of the rear lens group.

Abstract: A refractive inverse telephoto optical system (10) has a first lens doublet (12), a Pechan prism assembly (14) and a second lens doublet (16). The Pechan prism assembly (14) is spaced between the front negative doublet (12) and the rear positive doublet (16). The Pechan prism assembly (14) may be rotated and, as rotation occurs, the associated linear detector array is rotated around within the optical field of view.

Abstract: An air spaced reverse telephoto objective lens for use in a laser chemical vapor deposition system or the like having a quartz plate window. The objective lens includes a negative component having a first air-spaced doublet wherein each doublet element is made of crown glass and a negative meniscus crown glass element spaced from said first air-spaced doublet. The objective lens further includes an aperture stop, a positive component including second and third doublet components for effecting color correction, and a pair of bi-convex elements for effecting spherical aberration correction. The objective lens provides a common focal plane for both illuminating light and laser light passing through the objective lens and the quartz plate window.

Abstract: A wide angle lens system of the retrofocus type is provided which includes two lens units. The first lens unit is of negative power and includes a combination of a positive element having a high dispersion and a negative element having a low dispersion for correction of lateral color. The second lens unit is of positive power and includes a combination of a positive element having a low dispersion and a negative element having a high dispersion for correction of longitudinal color. The lens units satisfy the relationship that the magnitude of f.sub.1 is less than about 1.15 times f.sub.2 and preferably satisfy the relationship that the magnitude of f.sub.1 is less than f.sub.0. The first and second lens units each preferably include an aspheric surface. Applications of the lens system include rear projection television systems wherein a single lens is used to project light from three LCD light valves onto a viewing screen.

Abstract: Described herein is a retrofocus type wide angle lens system composed of a front group with a negative power and a rear group with a positive power, in which the front group is divided into a fixed group starting with a negative meniscus lens having a convex surface on the object side and terminating with a negative lens element having a concave surface on the image-forming side, and a corrective group starting with a positive lens element having a convex surface on the object side. The fixed group which is constituted by larger and heavier lens elements is held stationary relative to an image forming plane, while the corrective group of smaller and light-weight lens elements is movable in the direction of the optical axis concurrently with the rear group to vary the width of the air space between the respective groups at the time of focusing, thereby effectively correcting various aberrations which would otherwise occur in a conspicuous degree in infinite to near distance focusing.