Abstract: An image taking apparatus is equipped with a zoom lens system which comprises: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; and a fourth lens unit having a positive refractive power, at least the first lens unit, the second lens unit, and the third lens unit move during zooming from a wide-angle end to a telephoto end so that a space between the first lens unit and the second lens unit increases, a space between the second lens unit and the third lens unit decreases, and a space between the third lens unit and the fourth lens unit increases, and the first lens unit is arranged closer to an image side in the wide-angle end than that in the telephoto end.

Abstract: An electronic imaging apparatus includes a zoom optical system having, in order from the object side, a first lens unit with positive power, a second lens unit with negative power, and an aperture stop, in which the first lens unit is composed of a single positive power unit and the second lens unit has a single negative lens element located at the most object-side position, both surfaces of which are concave, and a positive lens component located at the most image-side position; an electronic image sensor located on the image side of the zoom optical system; and an image processing section electrically processing image data obtained by the electronic image sensor to change the form thereof.

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 relates to an optical system which, albeit being simple in construction, enables images of a wide range of natural subjects to be well reproduced with their colors, and provides an image pickup system comprising, at least, an image pickup optical system 1, an electronic image pickup device 3 having three or more different spectral characteristics to obtain a color image and a controller 4 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 comprises an optical element making use of a refraction phenomenon alone.

Abstract: The invention relates to a compact zoom lens system that has a decreased F-number and can easily achieve a high zoom ratio, and an imaging system that incorporates it. The zoom lens system comprises a first group G1 of positive power, a second group G2 of negative power, a third group G3 of positive power and a fourth group G4 of positive power. Upon zooming, at least the first group G1, the second group G2 and the third group G3 move on an optical axis in such a way that, at a telephoto end with respect to a wide-angle end, the space between the first group G1 and the second group G2 becomes wide, the space between the second group G2 and the third group G3 becomes narrow and the space between the third group G3 and the fourth group G4 becomes wide. The second group G2 is composed of a negative lens L21, a negative lens L22 and a positive lens L23.

Abstract: The present invention relates to a digital still camera that is compatible with an increasing number of pixels and uses a zoom lens having a high zoom ratio yet compact, simple construction, wherein chromatic aberration of the zoom lens are reduced and the zoom lens is kept against the influences of chromatic aberrations. The zoom lens comprises a lens group G2 having negative refracting power and at least one lens group G3 located on the image side of G2 and having positive refracting power. Upon zooming, the spacing between the negative lens group G2 and the positive lens group G3 changes. The positive lens group G3 includes two doublet components, in each of which a positive lens element and a negative lens element are cemented together in order from the object side of G3. The doublet component located on the image side of G3 has a meniscus form concave on its image side.

Abstract: A zoom image pickup optical system including, in order 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, in which at least the second lens unit and the fourth lens units are moved along an optical axis to change a magnification, in which the third lens unit includes at least two lens components, in which the fourth lens unit includes at least two lens components, and in which radii of curvature on at least one of pairs of surfaces of the third lens unit and the fourth lens unit such as an image side surface of a most image side lens component in the third lens unit and an object side surface of a most object side lens component in the fourth lens unit which correspond to each other with regard to an airspace between the third lens unit and the fourth lens unit have different signs.

Abstract: A zoom image pickup optical system including, in order 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, in which at least the second lens unit and the fourth lens units are moved along an optical axis to change a magnification, in which the third lens unit includes at least two lens components, in which the fourth lens unit includes at least two lens components, and in which radii of curvature on at least one of pairs of surfaces of the third lens unit and the fourth lens unit such as an image side surface of a most image side lens component in the third lens unit and an object side surface of a most object side lens component in the fourth lens unit which correspond to each other with regard to an airspace between the third lens unit and the fourth lens unit have different signs.

Abstract: The present invention relates to a digital still camera that is compatible with an increasing number of pixels and uses a zoom lens having a high zoom ratio yet compact, simple construction, wherein chromatic aberration of the zoom lens are reduced and the zoom lens is kept against the influences of chromatic aberrations. The zoom lens comprises a lens group G2 having negative refracting power and at least one lens group G3 located on the image side of G2 and having positive refracting power. Upon zooming, the spacing between the negative lens group G2 and the positive lens group G3 changes. The positive lens group G3 includes two doublet components, in each of which a positive lens element and a negative lens element are cemented together in order from the object side of G3. The doublet component located on the image side of G3 has a meniscus form concave on its image side.

Abstract: A zoom image pickup optical system including, in order 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, in which at least the second lens unit and the fourth lens units are moved along an optical axis to change a magnification, in which the third lens unit includes at least two lens components, in which the fourth lens unit includes at least two lens components, and in which radii of curvature on at least one or pairs of surfaces of the third lens unit and the fourth lens unit such as an image side surface of a most image side lens component in the third lens unit and an object side surface of a most object side lens component in the fourth lens unit which correspond to each other with regard to an airspace between the third lens unit and the fourth lens unit have different signs.

Abstract: A zoom image pickup optical system including, in order 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, in which at least the second lens unit and the fourth lens units are moved along an optical axis to change a magnification, in which the third lens unit includes at least two lens components, in which the fourth lens unit includes at least two lens components, and in which radii of curvature on at least one or pairs of surfaces of the third lens unit and the fourth lens unit such as an image side surface of a most image side lens component in the third lens unit and an object side surface of a most object side lens component in the fourth lens unit which correspond to each other with regard to an airspace between the third lens unit and the fourth lens unit have different signs.

Abstract: An image pickup optical system comprising, in order from the object side, a first lens component which comprises a meniscus lens element having a convex surface on the object side and a positive refractive power, a second lens component which comprises a negative lens element, a third lens component which comprises a negative meniscus lens element having a convex surface on the object side and a biconvex lens element, and a fourth lens component which comprises a negative meniscus lens element having a convex surface on the image side. This optical system is configured so as to have a large aperture, reserve a sufficient amount of marginal rays, and correct coma and curvature of field by disposing a stop on the object side of the third lens component and defining a refractive power of a cemented surface of the third lens component within a certain range.