Abstract: The invention is directed to inner-focusing zoom lenses that include multi groups of lens pieces, namely, the first lens group or the leading lens group of positive refractivity, the second lens group of negative refractivity, and the remaining trailing groups of positive refractivity, as a whole. At least one group of positive refractivity among the trailing groups includes two or more negative lens pieces, at least one of which is connected on its surface to another lens piece to form a duplicated composite lens so that the junction between two of them functions to diverge incident beams. Assuming now that a sum of the refractivities of all the junctions of the composite lenses can be expressed as ??=?|(N1?N2)/R| where N1 and N2 are refractivities that substances before and after the junction of the composite lenses respectively have, R is a radius of curvature of the junction, ft is a focal length of the comprehensive lens optics of the zoom lens at the telephoto end.

Abstract: The present invention is directed to high magnification compact zoom lenses that are reduced in diameter of groups of lens pieces closer to the imaging plane to provide downsized lightweight zoom lenses of magnification as high as 20 diameters, with an image stabilizer or vibration compensating mechanism being also reduced in dimensions. An exemplary improved high magnification zoom lens has four groups of lens pieces, namely, the first or leading lens group G1 of positive refractivity in the foremost position closer to the subject, the second lens group G2 of negative refractivity, the third lens group G3 of positive refractivity, and the fourth lens group G4 of positive refractivity in the rearmost position closer to the imaging plane, all arranged in this order.

Abstract: The present invention is directed to high magnification compact zoom lenses that are reduced in diameter of groups of lens pieces closer to the imaging plane to provide downsized lightweight zoom lenses of magnification as high as 20 diameters, with an image stabilizer or vibration compensating mechanism being also reduced in dimensions. An exemplary improved high magnification zoom lens has four groups of lens pieces, namely, the first or leading lens group G1 of positive refractivity in the foremost position closer to the subject, the second lens group G2 of negative refractivity, the third lens group G3 of positive refractivity, and the fourth lens group G4 of positive refractivity in the rearmost position closer to the imaging plane, all arranged in this order.

Abstract: A zoom lens includes sequentially from an object side, a positive first lens group; a negative second lens group; a diaphragm; a positive third lens group; a positive fourth lens group; and a positive fifth lens group, wherein a first condition 0.8?(SLM?(SLW+SLT)/2)/FW?2.0 and a second condition F14t?0 are satisfied. SLW is a distance from the diaphragm at a wide angle edge to an imaging plane; SLM is a distance from the diaphragm at an intermediate zoom position to the imaging plane; SLT is a distance from the diaphragm at a telephoto edge to the imaging plane; FW is optical system focal length for infinity at the wide angle edge; and F14t is a combined focal length for the first to the fourth lens groups at the telephoto edge.

Abstract: A zoom lens includes, sequentially from an object side, a positive first lens group; a negative second lens group; a positive third lens group; and a positive fourth lens group, where 2.0?D23W/FW?3.0 is satisfied. D23W is an interval, at a wide angle edge, between a lens that among lenses of the second lens group, is farthest on an imaging plane side and a lens that among lenses of the third lens group, is farthest on the object side. FW is a focal length of an optical system of the zoom lens at infinity focus, at the wide angle edge.

Abstract: An inner-focusing zoom lens that includes multi groups of lens pieces, namely, the first lens group or the leading lens group of positive refractivity, the second lens group of negative refractivity, and the remaining trailing groups of positive refractivity, as a whole. At least one group of positive refractivity among the trailing groups includes two or more negative lens pieces, at least one of which is connected on its surface to another lens piece to form a duplicated composite lens so that the junction between two of them functions to diverge incident beams. Assuming now that a sum of the refractivities of all the junctions of the composite lenses can be expressed as ??=?|(N1?N2)/R| where N1 and N2 are refractivities that substances before and after the junction of the composite lenses respectively have, R is a radius of curvature of the junction, ft is a focal length of the comprehensive lens optics of the zoom lens at the telephoto end.

Abstract: A zoom lens includes sequentially from an object side, a positive first lens group; a negative second lens group; a diaphragm; a positive third lens group; a positive fourth lens group; and a positive fifth lens group, wherein a first condition 0.8?(SLM?(SLW+SLT)/2)/FW?2.0 and a second condition F14t?0 are satisfied. SLW is a distance from the diaphragm at a wide angle edge to an imaging plane; SLM is a distance from the diaphragm at an intermediate zoom position to the imaging plane; SLT is a distance from the diaphragm at a telephoto edge to the imaging plane; FW is optical system focal length for infinity at the wide angle edge; and F14t is a combined focal length for the first to the fourth lens groups at the telephoto edge.

Abstract: The present invention is directed to wide-angle zoom lenses dedicated to single-lens reflex digital cameras, which attains zoom ratio greater than 2. Such a wide-angle zoom lens has four groups of lens pieces, namely comprising the leading or foremost 1st lens group of negative refractivity closest to an objective field, the succeeding 2nd lens group of positive refractivity, the third lens group of negative refractivity, and the trailing 4th lens group of positive refractivity arranged in this order to move each lens group to vary optical power; and the 1st lens group includes a front subset of the lens pieces of negative refractive power and a rear subset of negative refractive power. The front-end lens piece in the 1st lens group is shaped in negative meniscus lens that has its concave surface faced toward an imaging plane and has the opposite surfaces shaped aspherical. The front and rear subsets of the 1st lens group meet requirements of a focal length as expressed in the following formula: 3.

Abstract: The present invention is directed to a wide-angle zoom lens that attains the field of view ranging from 80 to 115 degrees in field angle with the zooming power of 2× or even higher, and that is capable of approximately compensating for various types of aberration such as spherical aberration, aberration of distortion, astigmatism and the like. The wide-angle zoom lens of multi groups of lens pieces, namely, a 1st lens group of negative refractivity, a 2nd lens group of negative refractivity, and a 3rd lens group of positive refractivity varies the power from the wide-angle end to the telephoto end with the 1st and 2nd lens groups coming closer to each other, and the 2nd and 3rd lens groups being varied in interval therebetween. The zoom lens attains the widest field of view of 80 degrees or over in field angle in the relations as expressed in the following formula: 2.

Abstract: The present invention is directed to high magnification compact zoom lenses that are reduced in diameter of groups of lens pieces closer to the imaging plane to provide downsized lightweight zoom lenses of magnification as high as 20 diameters, with an image stabilizer or vibration compensating mechanism being also reduced in dimensions. An exemplary improved high magnification zoom lens has four groups of lens pieces, namely, the first or leading lens group G1 of positive refractivity in the foremost position closer to the subject, the second lens group G2 of negative refractivity, the third lens group G3 of positive refractivity, and the fourth lens group G4 of positive refractivity in the rearmost position closer to the imaging plane, all arranged in this order.

Abstract: The present invention is directed to a compact large-aperture-ratio inner-focusing telephoto zoom lens of the reduced total lens extension where minimizing a photo-shooting distance down to as short as 1 meter does not cause the lens optics to displace accordingly greater during the focusing. The large-aperture-ratio inner-focusing telephoto zoom lens has four groups of lens pieces, namely, the 1st lens group of positive refractive power, the 2nd lens group of negative refractive power, the 3rd lens group of positive refractive power, and, the 4th lens group of positive refractive power arranged in series on the basis of “closer to a subject first,” and that has the 2nd and 3rd lens groups moved along the optical axis to vary a magnification power.

Abstract: The invention is directed to inner-focusing zoom lenses that include multi groups of lens pieces, namely, the first lens group or the leading lens group of positive refractivity, the second lens group of negative refractivity, and the remaining trailing groups of positive refractivity, as a whole. At least one group of positive refractivity among the trailing groups includes two or more negative lens pieces, at least one of which is connected on its surface to another lens piece to form a duplicated composite lens so that the junction between two of them functions to diverge incident beams. Assuming now that a sum of the refractivities of all the junctions of the composite lenses can be expressed as ??=?|(N1?N2)/R| where N1 and N2 are refractivities that substances before and after the junction of the composite lenses respectively have, R is a radius of curvature of the junction, ft is a focal length of the comprehensive lens optics of the zoom lens at the telephoto end.

Abstract: The present invention is directed to a wide-angle zoom lens that attains the field of view ranging from 80 to 115 degrees in field angle with the zooming power of 2× or even higher, and that is capable of approximately compensating for various types of aberration such as spherical aberration, aberration of distortion, astigmatism and the like. The wide-angle zoom lens of multi groups of lens pieces, namely, a 1st lens group of negative refractivity, a 2nd lens group of negative refractivity, and a 3rd lens group of positive refractivity varies the power from the wide-angle end to the telephoto end with the 1st and 2nd lens groups coming closer to each other, and the 2nd and 3rd lens groups being varied in interval therebetween. The zoom lens attains the widest field of view of 80 degrees or over in field angle in the relations as expressed in the following formula: 2.

Abstract: The present invention is directed to a compact large-aperture-ratio inner-focusing telephoto zoom lens of the reduced total lens extension where minimizing a photo-shooting distance down to as short as 1 meter does not cause the lens optics to displace accordingly greater during the focusing. The large-aperture-ratio inner-focusing telephoto zoom lens has four groups of lens pieces, namely, the 1st lens group of positive refractive power, the 2nd lens group of negative refractive power, the 3rd lens group of positive refractive power, and, the 4th lens group of positive refractive power arranged in series on the basis of “closer to a subject first,” and that has the 2nd and 3rd lens groups moved along the optical axis to vary a magnification power.