Abstract: The present invention relates to a compact and low-cost image pickup apparatus that is capable of photographing a high-quality image comparable to silver halide photographs even when the image is enlarged to 8×10? size or larger and that enables the depth of field to be controlled with an aperture number exceeding F4. In the image pickup apparatus, an image of an object produced by an optical system (10) is formed on an electronic image pickup device (20), thereby obtaining image information concerning the object. The optical system (10) has a structure capable of obtaining an aperture number equal to or larger than F4 by reducing the beam diameter. Performance required for the optical system (10) is such that the size of the diameter of 90% encircled energy of the point spread function by amplitude is allowed to be up to about 8 times larger than the pixel pitch corresponding to the resolvable pixel unit. The pixel pitch of the image pickup device (20) is not larger than about 5 micrometers.

Abstract: The invention relates to an electronic image pickup system that enables a wide image-pickup, and ensures that even when an image is printed, sufficient image quality and clearness are obtained from the center to as far as the margin of the image and the image of a subject is depicted with a sense of extension. The electronic image pickup system comprises an image-formation optical system 10 for forming an image of a subject and an electronic image pickup device 20 located on an image side of the image-formation optical system for obtaining image information on the image.

Abstract: The invention relates to an electronic image pickup system that enables a wide image-pickup, and ensures that even when an image is printed, sufficient image quality and clearness are obtained from the center to as far as the margin of the image and the image of a subject is depicted with a sense of extension. The electronic image pickup system comprises an image-formation optical system 10 for forming an image of a subject and an electronic image pickup device 20 located on an image side of the image-formation optical system for obtaining image information on the image.

Abstract: The invention relates to an electronic image pickup system that enables a wide image-pickup, and ensures that even when an image is printed, sufficient image quality and clearness are obtained from the center to as far as the margin of the image and the image of a subject is depicted with a sense of extension. The electronic image pickup system comprises an image-formation optical system 10 for forming an image of a subject and an electronic image pickup device 20 located on an image side of the image-formation optical system for obtaining image information on the image.

Abstract: The present invention relates to a compact and low-cost image pickup apparatus capable of photographing a high-quality image comparable to silver halide photographs, particularly an image in which color shift is inconspicuous. In the image pickup apparatus, an image of an object produced by an optical system 10 is formed on an electronic image pickup device 20, thereby obtaining image information concerning the object. The electronic image pickup device 20 and the optical system 10 satisfy the conditions: (1) 1.5<P<7.0; (2) 3.0<N<20; (3) 1.0×P<67 <5.0×P; and (4) nL/nT<0.25; where P is the pixel pitch (given in micrometers) of the image pickup device; N is the number of pixels (given in million) of the image pickup device; and &thgr; is the angle (°) at which the central ray of a light beam exiting from the optical system or a ray passing through the center of a stop is incident on the image pickup device at the maximum image height.

Abstract: The present invention relates to a compact and low-cost image pickup apparatus capable of providing high-quality images comparable to silver halide photographs and also capable of obtaining photographic effects equivalent to those which are available for silver halide photographs, e.g. utilization of blurring. In the image pickup apparatus, an image of an object produced by an optical system is formed on an electronic image pickup device, thereby obtaining image information concerning the object. The image pickup device 20 is a device having a matrix or mosaic color filter array provided over a photoelectric conversion surface, and the electronic image pickup device 20 and the optical system 10 satisfy the conditions: (1) 6.2/{square root over ( )}N<P<21/{square root over ( )}N; (2) 3.8<N<20; (3) 3.4×P−25<N<20; and (4) 0<&thgr;<1.

Abstract: The present invention relates to a compact and low-cost image pickup apparatus that is capable of photographing a high-quality image comparable to silver halide photographs even when the image is enlarged to 8×10″ size or larger and that enables the depth of field to be controlled with an aperture number exceeding F4. In the image pickup apparatus, an image of an object produced by an optical system (10) is formed on an electronic image pickup device (20), thereby obtaining image information concerning the object. The optical system (10) has a structure capable of obtaining an aperture number equal to or larger than F4 by reducing the beam diameter. Performance required for the optical system (10) is such that the size of the diameter of 90% encircled energy of the point spread function by amplitude is allowed to be up to about 8 times larger than the pixel pitch corresponding to the resolvable pixel unit. The pixel pitch of the image pickup device (20) is not larger than about 5 micrometers.

Abstract: A compact image pickup optical system capable of providing a clear image of minimal distortion even at a wide field angle, and an image pickup apparatus using such an image pickup optical system. The image pickup optical system forms an object image on the surface of an image pickup device (8). At least a rear optical unit (4) is provided on the image side of a pupil plane (1). The rear optical unit (4) has at least one reflecting surface decentered such that the whole surface is tilted with respect to an axial principal ray (2) defined by a light ray emanating from the object center and passing through the pupil center to reach the image center. The reflecting surface has a rotationally asymmetric surface configuration that corrects rotationally asymmetric decentration aberrations caused by decentration, thereby reducing rotationally asymmetric aberrations of the object image.

Abstract: The present invention relates to a compact and low-cost image pickup apparatus that is capable of photographing a high-quality image comparable to silver halide photographs even when the image is enlarged to 8×10″ size or larger and that enables the depth of field to be controlled with an aperture number exceeding F4. In the image pickup apparatus, an image of an object produced by an optical system (10) is formed on an electronic image pickup device (20), thereby obtaining image information concerning the object. The optical system (10) has a structure capable of obtaining an aperture number equal to or larger than F4 by reducing the beam diameter. Performance required for the optical system (10) is such that the size of the diameter of 90% encircled energy of the point spread function by amplitude is allowed to be up to about 8 times larger than the pixel pitch corresponding to the resolvable pixel unit. The pixel pitch of the image pickup device (20) is not larger than about 5 micrometers.

Abstract: The invention relates to an electronic image pickup system that enables a wide image-pickup, and ensures that even when an image is printed, sufficient image quality and clearness are obtained from the center to as far as the margin of the image and the image of a subject is depicted with a sense of extension. The electronic image pickup system comprises an image-formation optical system 10 for forming an image of a subject and an electronic image pickup device 20 located on an image side of the image-formation optical system for obtaining image information on the image.

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 telephoto lens system consisting of a front lens group and a rear lens group: the front lens group being composed of a first lens unit which is composed only of a positive lens components and a second lens unit which is composed only of negative lens components, and the rear lens group being composed of a third positive lens unit, a fourth negative lens unit and a fifth positive lens unit. This lens system has a back focal length long enough to permit disposing filters such as a low pass filter and optical path splitting members.

Abstract: A zoom lens system comprising, in order from the object side, a first positive lens unit, a second lens unit which is moved monotonously during zooming mainly for sharing a vari-focal function and has a positive power, a third positive lens unit, and a fourth lens unit which is moved during zooming forward and backward mainly for correcting a location of an image surface and has a positive power; the third lens unit consisting of a first lens component which comprises at least one positive lens element and a second lens component which comprises at least one negative lens element, whereas the fourth lens unit consisting of a first lens component which comprises at least one negative lens element and a second lens component which comprises at least one positive lens element.

Abstract: A zoom lens system comprising, in order from the object side, a first lens unit having a negative refractive power as a whole, a second lens unit having a negative refractive power as a whole and a third lens unit having a positive refractive power as a whole. This zoom lens system has a very wide field angle of approximately 102.degree. to 93.degree., a high aperture ratio of F/2.8 and a relatively simple composition.

Abstract: The invention provides an ultra-wide zoom lens system that has a very wide angle coverage, as indicated by a field angle change of about 92.degree. to about 65.degree., is bright, as indicated by an F-number of 4.5 at the telephoto end, and is relatively simple in lens unit construction, and consists of, in order from the object side, a first lens unit I of negative refracting power, a second lens unit II of positive refracting power and a third lens unit III of negative refracting power, all said lens units being moved toward the object side for wide angle to telephoto zooming. The zoom lens system then conforms to Conditional Formulae (1), (2) and (3):-6.5<f.sub.1 /f.sup.T <-1.5 (1)0.4<f.sub.2 /f.sup.T <1.0 (2)0.8<e.sub.1.sup.W /e.sub.1.sup.T <1.2 (3)where f.sub.1 and f.sub.2 are the focal lengths of the first and second lens units, respectively, f.sup.T is the focal length of the overall lens system at the telephoto end, and e.sub.1.sup.W and e.sub.1.sup.

Abstract: A microscope objective lens system comprising a plurality of lenses, at least one of the lenses being a graded refractive index lens (GRIN lens) whose refractive index varies as the radial distance from the optical axis varies, which is simpler in construction and in which aberrations are corrected sufficiently to a wide range of NA.

Abstract: A compact zoom lens system with a high zooming ratio comprises, in order from the object side, a first lens group having a positive refracting power, a second lens group having a positive refracting power and a third lens group having a negative refracting power, in which the first lens group, the second lens group and the third lens group are respectively moved on the optical axis toward the object side during the zooming operation taking place from the wide-angle position as the reference point to the telephoto position, and at least one graded refractive index lens of an axial type which has the distribution of its refractive index in the direction of the optical axis is arranged in at least one lens group, so that the zooming ratio exceeds 2, the fluctuation of aberrations during the zooming operation is small and the flatness of the image surface is favorable.

Abstract: A microscope objective comprising a first lens component, a second lens component located in a range wherein the height of paraxial marginal ray becomes at least a half of the maximum height of paraxial marginal ray to be reached in the microscope objective, and a third lens component, the second lens component being arranged as a graded refractive index (GRIN) lens formed that the refractive index thereof is graded according to the radial distance from the optical axis and, moreover, the dispersion in the marginal portion thereof is different from the dispersion in the central portion thereof, the microscope objective being arranged that chromatic aberration as well as aberrations for the basic wavelength are corrected satisfactorily favorably.

Abstract: A graded refractive index (GRIN) lens that is compact and light in weight comprising two refracting surfaces having positive powers respectively, at least one refracting surface being formed aspherically, thereby enabling to have spherical aberration, coma, astigmatism, etc., well-corrected while securing a sufficiently large working distance.

Abstract: An eyepiece comprising at least one graded refractive index (GRIN) lens formed that the refractive index thereof is graded according to the radial distance from the optical axis, the eyepiece being arranged to comprise a small number of lenses and to have a long eye relief about 0.8 time of the focal length and an angle of view of 45.degree. or more and arranged that aberrations thereof, especially astigmatism and distortion, are corrected satisfactorily favorably.