Abstract: A zoom lens comprises, in order from its object side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. The first lens unit comprises a first lens having a negative refractive power and a second lens having a positive refractive power. The zoom lens satisfies the following conditional expressions (1), (2), and (3): n1n?1.70??(1), n1p?1.70??(2), and |?1n??1p?31??(3), where n1n is the refractive index of the first lens having a negative refractive power in the first lens unit for the d-line, ?1n is the Abbe constant of the first lens having a negative refractive power in the first lens unit, n1p is the refractive index of the second lens having a positive refractive power in the first lens unit for the d-line, and ?1p is the Abbe constant of the second lens having a positive refractive power in the first lens unit.

Abstract: A zoom lens comprises, in order from its object side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. The first lens unit comprises a first lens having a negative refractive power and a second lens having a positive refractive power. The zoom lens satisfies the following conditional expressions (1), (2), and (3): n1n?1.70??(1), n1p?1.70??(2), and |?1n??1p?31??(3), where n1n is the refractive index of the first lens having a negative refractive power in the first lens unit for the d-line, ?1n is the Abbe constant of the first lens having a negative refractive power in the first lens unit, n1p is the refractive index of the second lens having a positive refractive power in the first lens unit for the d-line, and ?1p is the Abbe constant of the second lens having a positive refractive power in the first lens unit.

Abstract: There is disclosed a light projection optical system comprising a light source; a relay lens unit which has a negative lateral magnification and which converts a luminous flux that has diverged from the light source into converged light; and a projection lens unit which reduces a divergent angle of the luminous flux from the relay lens unit to convert a state of the luminous flux into a state close to that of a parallel luminous flux and which projects light toward a target region, wherein the following conditions are satisfied: 0.9<?r<3.0 ??(1); and 1.0<(1+?r)(fr/|fo|)<6.0 ??(2), in which ?r is an absolute value of the lateral magnification of the relay lens unit, fr is a focal length of the relay lens unit and fo is a focal length of the projection lens unit.

Abstract: An optical system is presented that enables images of a wide range of natural subjects to be well reproduced with their colors, and provides an image pickup system including, at least, an image pickup optical system, an electronic image pickup device having three or more different spectral characteristics to obtain a color image, and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in determining the focal length in the image pickup system includes an optical element making use of a refraction phenomenon alone.

Abstract: An optical system is presented that enables images of a wide range of natural subjects to be well reproduced with their colors, and provides an image pickup system including, at least, an image pickup optical system, an electronic image pickup device having three or more different spectral characteristics to obtain a color image, and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in determining the focal length in the image pickup system includes an optical element making use of a refraction phenomenon alone.

Abstract: An optical system enables images to be well reproduced with their colors, and provides an image pickup system including an image pickup optical system, an electronic image pickup device to obtain a color image and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in the determination of a focal length includes an optical element making use of a refraction phenomenon alone. The 400-nm wavelength input/output ratio is 10% or less with respect to an input-output ratio for a 400-nm to 800-nm wavelength at which an output signal strength ratio with respect to an input quantity of light is highest when the input quantity of light is defined by the quantity of a light beam emanating from the same object point and entering the image pickup optical system and the output signal strength is defined by the strength of a signal produced from the controller in response to the light beam.

Abstract: An optical system enables images of a wide range of natural subjects to be well reproduced with their colors, and provides an image pickup system including, at least, an image pickup optical system, an electronic image pickup device having three or more different spectral characteristics to obtain a color image, and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in the determination of a focal length in said image pickup system includes an optical element making use of a refraction phenomenon alone.

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: There is disclosed a light projection optical system comprising a light source; a relay lens unit which has a negative lateral magnification and which converts a luminous flux that has diverged from the light source into converged light; and a projection lens unit which reduces a divergent angle of the luminous flux from the relay lens unit to convert a state of the luminous flux into a state close to that of a parallel luminous flux and which projects light toward a target region, wherein the following conditions are satisfied: 0.9<?r<3.0 ; and ??(1) 1.0<(1+?r)(fr/|fo|)<6.0 , ??(2) in which ?r is an absolute value of the lateral magnification of the relay lens unit, fr is a focal length of the relay lens unit and fo is a focal length of the projection lens unit.

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention relates to an image-formation optical system capable of achieving wide-angle arrangement and compactness at the same time and an imaging system that incorporates the same. The image-formation optical system is made up of, in order from its object side, a first positive lens L1, a second negative lens L2, a third positive lens L3 and a fourth positive lens L4. The composite focal length of the first positive lens L1 and the second negative lens L2 is positive, or the composite focal length of the second negative lens L2, the third positive lens L3 and the fourth positive lens L4 is negative.

Abstract: An optical system is presented that enables images of a wide range of natural subjects to be well reproduced with their colors, and provides an image pickup system including, at least, an image pickup optical system, an electronic image pickup device having three or more different spectral characteristics to obtain a color image, and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in determining the focal length in the image pickup system includes an optical element making use of a refraction phenomenon alone.

Abstract: An optical system is presented that enables images of a wide range of natural subjects to be well reproduced with their colors, and provides an image pickup system including, at least, an image pickup optical system, an electronic image pickup device having three or more different spectral characteristics to obtain a color image, and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in determining the focal length in the image pickup system includes an optical element making use of a refraction phenomenon alone.

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: An optical system enables images to be well reproduced with their colors, and provides an image pickup system including an image pickup optical system, an electronic image pickup device to obtain a color image and a controller for implementing signal processing or image processing on the basis of an output from the electronic image pickup device. The optical element that takes part in the determination of a focal length includes an optical element making use of a refraction phenomenon alone. The 400-nm wavelength input/output ratio is 10% or less with respect to an input-output ratio for a 400-nm to 800-nm wavelength at which an output signal strength ratio with respect to an input quantity of light is highest when the input quantity of light is defined by the quantity of a light beam emanating from the same object point and entering the image pickup optical system and the output signal strength is defined by the strength of a signal produced from the controller in response to the light beam.

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention relates to a stereo imaging unit or system that can have a suitable degree of parallax and a wide angle of view even when used with an image pickup device smaller than film.