Abstract: An image pickup apparatus, including: a filter including transmittance variable element and adjusting amount of incident light from lens; a photoelectric transducer; and guide optical system guiding the incident light from the filter to the photoelectric transducer. The guide optical system includes color separation optical system including, in order from object side, first prism having first dichroic film, second prism having second dichroic film, and third prism, to separate the incident light into red, green, and blue. The first or second dichroic film is blue reflection dichroic film. Rotational position of the transmittance variable element about optical axis is such a position that ratio of transmittance for blue to transmittance for green of marginal ray entering the blue reflection dichroic film at incident angle smaller than principal ray of axial ray to the blue reflection dichroic film is smaller than such ratio of the principal ray of axial ray.

Abstract: A zoom lens includes, in order from an object side, a first unit that does not move, a negative second unit which moves during zooming, a positive third unit which moves during zooming, a positive fourth unit which moves during zooming and focus adjustment, an aperture stop that does not move in an optical axis direction, and a positive fifth unit which does not move, wherein Zinf representing a zooming ratio of the entire zoom lens when focused on infinity, ?3winf and ?3tinf representing lateral magnifications of the third unit at the wide angle end and a telephoto end, respectively, when focused on infinity, ?4tinf and ?5tinf representing lateral magnifications of the fourth unit and the fifth unit, respectively, at the telephoto end when focused on infinity, and f3 and f4 representing focal lengths of the third unit and the fourth unit, respectively, satisfy predetermined conditional expressions.

Abstract: An image pickup apparatus includes: a lens apparatus; and a camera apparatus that can be attached and removed from the lens apparatus, wherein the camera apparatus includes: an image pickup element; and an optical element configured to be inserted and removed from an optical path, the optical element is a ND filter, and the ND it has a surface with positive refractive power. A ratio of a thickness of the optical element on an optical axis and a thickness of the optical length adjustment unit on the optical axis is appropriately set.

Abstract: A zoom lens includes, in order from the object side, a positive first lens unit which does not move for zooming or focusing, a negative second lens unit which moves during zooming, a positive third lens unit which moves during zooming, a negative fourth lens unit which moves during zooming and focusing, and a positive fifth lens unit which does not move for zooming or focusing. An aperture stop which does not move for zooming or focusing is arranged adjacent to the fourth lens unit. The focal lengths of the second, third, and fourth lens units, a zoom ratio of the zoom lens at infinity focus, the lateral magnification of the third lens unit at the wide angle end and the telephoto end at infinity focus, the lateral magnifications of the fourth and fifth lens units at the telephoto end at infinity focus are appropriately set.

Abstract: A zoom lens including, in order from object side to image side: a first positive lens unit which does not move for zooming; a second negative lens unit which moves during zooming; a third positive lens unit which moves during zooming; a fourth lens unit which moves during zooming; and a fifth positive lens unit which does not move for zooming. The second unit passes through a point at which magnification of the second unit becomes ?1 during zooming from wide-angle end to telephoto end, and ?1<?34<?0.3, and 4.0<|m2/m3|<15 are satisfied where ?34 represents a magnification of a combined unit including the third and fourth units at a zoom position fz at which the magnification of the second unit becomes ?1, and m2 and m3 respectively represent displacements of the second and third units on optical axis at the zoom position fz with reference to the wide-angle end.

Abstract: A tele-side converter lens including a first unit having a positive refractive power and a second unit having a negative refractive power, in which: the first unit includes one or two positive lenses; the second unit includes one negative lens and one or two positive lenses; and average Abbe constant and partial dispersion ratio of materials of positive lenses constituting the first unit, average Abbe constant and partial dispersion ratio of materials of positive lenses constituting the second unit, an Abbe constant and a partial dispersion ratio of materials of the negative lenses constituting the second unit, combined Abbe constants of materials of the lenses constituting the respective first and second units, focal lengths of the first and second units, a refractive index of a material of a positive lens disposed closest to the object side, and a magnification of the tele-side converter lens are appropriately set, respectively.

Abstract: A zoom lens includes a first lens unit, a second lens unit, a third lens unit, a fourth lens unit and a fifth lens unit. In the zoom lens, air intervals L2w, L3w between the second lens unit and the third lens unit and between the third lens unit and the fourth lens unit at a wide-angle end, a focal length f1 of the first lens unit, a combined focal length f23w of the second lens unit and the third lens unit at the wide-angle end, a focal length fw of the whole system at the wide-angle end, a zoom ratio Z, and a smallest value L2z1a of the air interval between the second lens unit and the third lens unit in a wide angle zoom range in which a magnification-varying ratio relative to that at the wide-angle end ranges from Z0.02 to Z0.35 are appropriately set.

Abstract: A zoom lens includes a first lens unit having a positive refractive power which does not move for zooming; a second lens unit having a negative refractive power which moves during zooming; a third lens unit having a negative refractive power which moves during zooming; a fourth lens unit having a positive refractive power which moves during zooming; and a fifth lens unit having a positive refractive power which does not move for zooming. Air intervals (L2w and L2t) between the second lens unit and the third lens unit at a wide-angle end and at a telephoto end, respectively, an air interval (L3w) between the third lens unit and the fourth lens unit at the wide-angle end, a focal length (f1) of the first lens unit, and a combined focal length (f23w) of the second lens unit and the third lens unit at the wide-angle end are appropriately set.

Abstract: A zoom lens includes, in order from an object side, a first unit that does not move, a negative second unit which moves during zooming, a positive third unit which moves during zooming, a positive fourth unit which moves during zooming and focus adjustment, an aperture stop that does not move in an optical axis direction, and a positive fifth unit which does not move, wherein Zinf representing a zooming ratio of the entire zoom lens when focused on infinity, ?3winf and ?3tinf representing lateral magnifications of the third unit at the wide angle end and a telephoto end, respectively, when focused on infinity, ?4tinf and ?5tinf representing lateral magnifications of the fourth unit and the fifth unit, respectively, at the telephoto end when focused on infinity, and f3 and f4 representing focal lengths of the third unit and the fourth unit, respectively, satisfy predetermined conditional expressions.

Abstract: A zoom lens, including, in order from object side: a positive first unit which is fixed during zooming; a negative second unit which moves for zooming; a positive third unit which moves for zooming; a positive fourth unit which moves for zooming; and a positive fifth unit which is fixed during zooming, in which 1.50<LN(Z2)/LN(Z34)<2.30 and 0.70<f34w/f34t<0.96 are satisfied, where LN(Z2) is natural logarithm of Z2 obtained by dividing a lateral magnification ?2t of the second unit at telephoto end by a lateral magnification ?2w at wide angle end, LN(Z34) is natural logarithm of Z34 obtained by dividing a combined lateral magnification ?34t of the third unit and the fourth unit at telephoto end by a combined lateral magnification ?34w at wide angle end, and f34w and f34t are combined focal lengths of the third unit and the fourth unit at wide angle end and telephoto end, respectively.

Abstract: Provided is an adapter optical system attachable between an image pickup lens and a camera body, the adapter optical system including, in order from an object side: a first optical unit having negative refractive power; a second optical unit that is insertable in and removable from an optical path; and a third optical unit having positive refractive power, in which the following expression is satisfied: 0.03<|?2|<0.50, where ?a2 represents an incident converted inclination angle obtained by normalizing an incident inclination angle of an axial beam entering the second optical unit inserted in an optical path with an exit inclination angle of an axial paraxial ray emerging from a surface closest to an image plane side in the adapter optical system being set to one (1).

Abstract: A zoom lens includes a first lens unit, a magnification-varying system including at least a second lens unit and a third lens unit, and a fourth lens unit. The fourth lens first unit has a first lens subunit having a negative refractive power, a second lens subunit having a negative refractive power, and a third lens subunit having a positive refractive power. The fourth lens unit satisfies the following conditional expression: 1.2<f41/f42<3.5, where f41 represents a focal length of the first lens subunit, and f42 represents a focal length of the second lens subunit.

Abstract: An image pickup apparatus, including: a filter including transmittance variable element and adjusting amount of incident light from lens; a photoelectric transducer; and guide optical system guiding the incident light from the filter to the photoelectric transducer. The guide optical system includes color separation optical system including, in order from object side, first prism having first dichroic film, second prism having second dichroic film, and third prism, to separate the incident light into red, green, and blue. The first or second dichroic film is blue reflection dichroic film. Rotational position of the transmittance variable element about optical axis is such a position that ratio of transmittance for blue to transmittance for green of marginal ray entering the blue reflection dichroic film at incident angle smaller than principal ray of axial ray to the blue reflection dichroic film is smaller than such ratio of the principal ray of axial ray.

Abstract: A wide-angle converter lens capable of being detachably mounted on an enlargement side of an imaging lens includes a first optical element, at least one optical element having negative refractive power, and at least one optical element having positive refractive power, wherein, when an average value of relative partial dispersions of the first optical element and all optical elements of which the sign of refractive power is the same as that of the first optical element is denoted by ?gF_ave, a relative partial dispersion of the first optical element is denoted by ?gF, and an Abbe number of the first optical element is denoted by ?d, these numerical values satisfy appropriate relationships.

Abstract: A wide-angle converter lens capable of being detachably mounted on an enlargement side of an imaging lens includes a first optical element, at least one optical element having negative refractive power, and at least one optical element having positive refractive power, wherein, when an average value of relative partial dispersions of the first optical element and all optical elements of which the sign of refractive power is the same as that of the first optical element is denoted by ?gF_ave, a relative partial dispersion of the first optical element is denoted by ?gF, and an Abbe number of the first optical element is denoted by ?d, these numerical values satisfy appropriate relationships.

Abstract: Provided is an adapter optical system attachable between an image pickup lens and a camera body, the adapter optical system including, in order from an object side: a first optical unit having negative refractive power; a second optical unit that is insertable in and removable from an optical path; and a third optical unit having positive refractive power, in which the following expression is satisfied: 0.03<|?a2|<0.50, where ?a2 represents an incident converted inclination angle obtained by normalizing an incident inclination angle of an axial beam entering the second optical unit inserted in an optical path with an exit inclination angle of an axial paraxial ray emerging from a surface closest to an image plane side in the adapter optical system being set to one (1).

Abstract: A zoom lens includes a first lens unit, a second lens unit, a third lens unit, a fourth lens unit and a fifth lens unit. In the zoom lens, air intervals L2w, L3w between the second lens unit and the third lens unit and between the third lens unit and the fourth lens unit at a wide-angle end, a focal length f1 of the first lens unit, a combined focal length f23w of the second lens unit and the third lens unit at the wide-angle end, a focal length fw of the whole system at the wide-angle end, a zoom ratio Z, and a smallest value L2z1a of the air interval between the second lens unit and the third lens unit in a wide angle zoom range in which a magnification-varying ratio relative to that at the wide-angle end ranges from Z0.02 to Z0.35 are appropriately set.

Abstract: A zoom lens includes a first lens unit having a positive refractive power which does not move for zooming; a second lens unit having a negative refractive power which moves during zooming; a third lens unit having a negative refractive power which moves during zooming; a fourth lens unit having a positive refractive power which moves during zooming; and a fifth lens unit having a positive refractive power which does not move for zooming. Air intervals (L2w and L2t) between the second lens unit and the third lens unit at a wide-angle end and at a telephoto end, respectively, an air interval (L3w) between the third lens unit and the fourth lens unit at the wide-angle end, a focal length (f1) of the first lens unit, and a combined focal length (f23w) of the second lens unit and the third lens unit at the wide-angle end are appropriately set.

Abstract: An image pickup apparatus includes: a lens apparatus; and a camera apparatus that can be attached and removed from the lens apparatus, wherein the camera apparatus includes: an image pickup element; and an optical element configured to be inserted and removed from an optical path, the optical element is a ND filter, and the ND it has a surface with positive refractive power. A ratio of a thickness of the optical element on an optical axis and a thickness of the optical length adjustment unit on the optical axis is appropriately set.

Abstract: A zoom lens, including: a first lens unit; a second lens unit; a magnification-varying system including two or more lens units; and a fourth lens unit, in which: the fourth lens unit includes: a forth lens first unit having a negative refractive power; a forth lens second unit having a negative refractive power that moves so as to have a component perpendicular to an optical axis so that an image is displaced in a direction perpendicular to the optical axis; and a forth lens third unit having a positive refractive power; and the following conditional expression is satisfied: 1.2<f41/f42<3.5, where f41 represents a focal length of the forth lens first unit, and f42 represents a focal length of the forth lens second unit.