Abstract: A long focal length microlens system that controls the variation of the aberration from the infinite object distance to shooting at equal magnification. The long focal length microlens system includes a first lens group G1 of positive refractive power a second lens group G2 of positive refractive power and a third lens group G3 of negative refractive power. When focusing from a infinite object distance to a close shooting distance, a value of D1 is reduced while a value of D2 is increased and a condition of 0.16<.vertline..DELTA.D1 .vertline./.DELTA.D2<0.5 is satisfied where D1 is a gap of lens apexes between said first group G1 and the second group G2. D2 is a gap of lens apexes between said second group G2 and the third group G3, .DELTA.D1 is (D1 at any object distance)-(D1 in the infinite object distance) and .DELTA.D2 is (D2 at any shooting distance)-(D2 in the infinite object distance).

Abstract: A telephoto lens includes, in the following order from the object side, a positive cemented lens component composed of a biconvex lens and a biconcave lens and having a meniscus shape as a whole with the convex side facing the object side, and a negative meniscus lens component with the convex side facing the image side.

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: The internal focusing telephoto lens of the invention has a focusing group with a small effective diameter and small focusing movement amount and maintains favorable optical performance. The internal focusing telephoto lens of the invention includes, in the following order from the object side; a first lens group that has a positive refractive power, a second lens group that has negative refractive power, and a third lens group that has a positive refractive power. The first and second lens groups form a substantially afocal system and focusing is performed by moving the second lens group along the optical axis. The first lens group includes, in the following order from the object side, a front group that has a positive refractive power and a rear group, which has about the same positive refractive power as the front group, and satisfies specified conditions.

Abstract: Disclosed is a telephoto-type lens system of a head separated charge coupled device (CCD) camera, which includes a first lens group having a positive focal length, a second lens group having a negative focal length, and a third lens group. The first lens group has a first convex lens surface facing an object and an upper convex surface. The third lens group has a second lens with a negative focal length joined to a first lens with a positive focal length. An image angle greater than 29.degree. and high definition images can be achieved with the present invention.

Abstract: The invention provides a telephoto lens system that enables the camera operator to shoot an infinite to nearby object with stably maintained optical quality. This lens system comprises a first positive lens unit G.sub.1, a second positive lens unit G.sub.2, a third negative lens unit G.sub.3 and a fourth positive lens unit G.sub.4. The first unit comprises at least two positive lenses and a negative meniscus lens heavily concave on the image surface side; the second unit comprises a positive lens heavily convex on the object side and a doublet consisting of negative and positive lenses; the third unit comprises a doublet consisting of negative and positive lenses; and the fourth unit comprises a cemented doublet consisting of negative and positive lenses. While the first and second units remain fixed, the third and fourth units are moved for focusing. Specific conditions regarding the focal lengths of the units, the separation between adjacent units, and the amount of movement of the units are satisfied.

Abstract: In a large-aperture medium-range telephoto lens system, which includes, in the following order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, and attains focusing by moving the second and third lens units along the optical axis while the first lens unit is fixed in position, the telephoto lens system satisfies:______________________________________ 0.8 < f1/f < 1.5 -3.0 < f2/f < -1.0 0.7 < f3/f < 1.0 0.02 < .vertline.x2/x3.vertline. < 0.

Abstract: An optical system includes, in the following order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, the second lens unit comprising, in the following order from the object side, a front lens group of a negative refractive power and a rear lens group of a negative refractive power, and a third lens unit having a positive refractive power. In the optical system, focusing to a short-distance object is attained by moving the second lens unit toward the image side, and the optical system satisfies:2.5<f2R/f2F<50.ltoreq.D2/f.ltoreq.0.10.15<1/(.vertline..phi.2F.vertline..multidot.f)<0.25where f2F is the focal length of a negative lens, closest to the object side, in the second lens unit, f2R is the focal length of a negative lens, closest to the image side, in the second lens unit, f is the focal length of the entire optical system, .phi.

Abstract: A high-aperture-ratio inner-focus telephoto lens comprises a first lens group of positive refracting power, a second lens group of negative refracting power and a third lens group of positive refracting power arranged in the named order from the object side, in which the first lens group and the second lens group form a substantially afocal system, focusing is effected by moving the second lens group along the optical axis, and the first lens group has a front group of positive refracting power and a rear group of weak positive refracting power arranged in the named order from the object side.

Abstract: In an internal focus telephoto lens comprised, in succession from the object side, of a first lens unit of positive refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power, the first lens unit of positive refractive power and the second lens unit of negative refractive power together forming a substantially afocal system, focusing being effected by the second lens unit, the first lens unit has a front group of positive refractive power and a rear group having weak positive refractive power relative to the front group, the first group being comprised, in succession from the object side, of a positive lens component, a positive lens component and a negative lens component, the second lens unit has, in succession from the object side, at least a negative lens component and a negative lens component, and the third lens unit has a positive lens component, and various predetermined conditions are satisfied.

Abstract: A great aperture zoom lens has, in succession from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. The second lens unit has, in succession from the object side, a negative lens component, a negative lens component, a positive lens component and a negative lens component. In case of the magnification change from the wide angle end to the telephoto end, the first lens unit, the third lens unit and the fourth lens unit are moved toward the object side. The zoom lens satisfies various predetermined conditions.

Abstract: A micro lens allowing a short-distance photographing operation from infinity to an equal magnification consists of, in order from the object side, a first lens group including a negative lens and having a positive refracting power, a second lens group having a positive refracting power, a third lens group including a cemented lens (doublet lens) and having a negative refracting power, and a fourth lens group having a positive refracting power. When a focusing operation is performed from infinity to a short distance, the first lens group is nonlinearly moved and the group interval between the second and third lens groups is increased, thereby satisfying required conditions.

Abstract: The telephoto lens is in each case put together from two different lens systems, a front group and a focusing group. The object-side front groups have fixedly arranged lens elements or lens element groups and the image-side focusing groups have mutually displaceable lens elements or lens element groups. The focal lengths of the focusing groups are chosen such that with the front groups, they produce telephoto lenses of different overall focal lengths. The front groups can be combined in a modular manner with the focusing groups. Telephoto lenses having excellent imaging performances can be put together with reduced production expenditure. The numerical data of a number of lens parts are specified.

Abstract: A telephoto lens system that adopts an inner focusing method and that is capable of satisfactory correction of aberrations while insuring an adequate back focus without increasing the overall lens length. The present telephoto lens system comprises, in order from the object side, a positive first lens group, a negative second lens group and a positive third lens group. The system can be focused on a close-up object by moving the second lens group toward the image. The first lens group comprises a positive first sub-group 1a and a positive second sub-group 1b separated from the first sub-group airspace. The system satisfies the following conditions:(1) 1.4<f/f.sub.1 <2.0(2) -3.5<f/f.sub.2 <-2.5(3) 0.4<f/f.sub.1b <1.0(4) 0.1<d.sub.1ab /f.sub.1 <0.3where f is the focal length of the overall system; f.sub.1 is the focal length of the first lens group; f.sub.2 is the focal length of the second lens group; f.sub.1b is the focal length of the sub-group 1b; and d.sub.

Abstract: An internal focusing telephoto lens includes, in succession from the object side, a first lens unit of positive refractive power having at least a positive first lens component, a second lens unit having negative refractive power and movable along the optical axis for focusing, and a third lens unit having positive refractive power and having an imaging function. The first lens unit forms a substantially afocal system with the second lens unit, and is designed to satisfy the following conditions:0.43<.phi./f.sub.1 <0.750.39<f.sub.1 /F<0.55,where.phi.: the effective diameter of the object side lens surface of the positive first lens component in the first lens unit,f.sub.1 : the focal length of the first lens unit,F: the focal length of the entire system.

Abstract: A simple zoom lens is disclosed having lens units of negative, positive and negative powers in this order from the object side, zooming from the wide-angle end to the telephoto end being performed by moving each lens unit toward the object side, and at least the leading negative and positive lens units each consisting of one lens.

Abstract: A large aperture, medium telephoto lens system is disclosed which is composed of a front group G.sub.F that comprises, in order from the object side, at least two positive lens elements having a strong convex surface directed toward the object and a negative lens having a strong concave surface directed toward the image and which has a positive overall refractive power, and a rear group G.sub.R with a surface S.sub.R1 which is the closest to the object being convex toward the object and which the a positive overall refractive power, with only the rear group G.sub.R being moved along the optical axis to perform focusing operations.

Abstract: An image blur compensating telephotographic lens has four lens groups. The four lens groups comprise a first lens group having a positive power, a second lens group having a negative power, a third lens group having a positive power, and a fourth lens group having a negative power arranged in this order from an object side. In one embodiment, the telephotographic lens has a lens moving mechanism for moving the second lens group in a direction vertical to the optical axis in order to compensate for an image blur when a photograph is taken. In another embodiment, the telephotographic lens has a lens moving mechanism for moving the third lens group in a direction vertical to the optical axis in order to compensate for an image blur when a photograph is taken.

Abstract: A telephoto zoom lens system featuring a zoom ratio on the order of 3 which uses an inexpensive optical material having a lens refractive index and which is compact in size can be attained. A first lens group I closest to the object side has a positive refractive power. The first lens group I includes a first negative maniscus lens element having a convex surface directed toward the object and a second positive lens element having a convex surface with a large curvature directed toward the object. A second lens group II having a negative refractive power is located on the image side of the first lens group I. A third lens group III having a positive refractive power is located on the image side of second lens group II. Lens group III includes a first lens unit IIIa having a positive refractive power and a second lens unit IIIb having a positive or negative refractive power. Zooming is performed by moving the three lens groups independently of one another along the optical axis.

Abstract: A telephoto lens system which composed of a front group comprising, in order from the object side, a positive first lens having a convex surface of large curvature directed toward the object, a positive meniscus second lens having a convex surface of large curvature directed toward the object and a negative third lens having a concave surface of large curvature directed toward the image, and a rear group comprising, in order from the object side, a biconvex fourth lens, a biconcave fifth lens, a positive sixth lens and a seventh lens having a weak positive refractive power, all lenses except the seventh lens being moved in unison to effect focusing. The lens system satisfies conditions which result in a light weight lens system having a focal length of about 100 mm and a large effective aperture ratio of 1:2.0, and which is capable of satisfactory compensation for spherical aberration and astigmatism over a shooting range from infinity to close-up at a magnification of about -0.1.times..