Imaging system

An imaging system comprising:

• a zoom lens comprising a plurality of lens groups wherein a spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device located on an image side of the zoom lens, wherein:
• the aperture stop has a fixed shape, and a filter for performing light quantity control by varying transmittance is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located,
• the zoom lens comprises at least a first lens group having negative refracting power and a second lens group having positive refracting power, located just after the first lens group,
• a spacing between the first lens group having negative refracting power and the second lens group having positive refracting power becomes narrower at a telephoto end than at a wide-angle end of the zoom lens,
• the aperture stop is located between a surface in the first lens group having negative refracting power, said surface being located nearest to an image side of the zoom lens, and an image side-surface in the second lens group having positive refracting power,
• the light quantity control filter is located on an image plane side with respect to the aperture stop,
• when the focal length is varied, the aperture stop is moved with the second lens group, and
• the imaging system constantly satisfies condition (1):
• 0.01<α/β<1.3 (1)
• where α is an axial distance from the aperture stop to an entrance surface of the light quantity control filter located on an image side with respect thereto, and β is an axial distance from the entrance surface of the light quantity control filter to an image pickup plane of the electronic image pickup device.

An imaging system comprising:

• a zoom lens comprising a plurality of lens groups wherein a spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device located on an image side of the zoom lens, wherein:
• the aperture stop has a fixed shape, and a filter for performing light quantity control by varying transmittance is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located,
• the zoom lens comprises at least a first lens group having negative refracting power and a second lens group having positive refracting power, located just after the first lens group,
• a spacing between the first lens group having negative refracting power and the second lens group having positive refracting power becomes narrower at a telephoto end than at a wide-angle end of the zoom lens,
• the aperture stop is located between a surface in the first lens group having negative refracting power, said surface being located nearest to an image side of the zoom lens, and an image side-surface in the second lens group having positive refracting power,
• the light quantity control filter is located on an image plane side with respect to the aperture stop,
• when the focal length is varied, the aperture stop is moved with the second lens group, and
• the imaging system satisfies condition (2):
• 0.5<φβ/φα<1.5 (2)
• where φα is a maximum diameter of an aperture in the aperture stop and φβ is a maximum effective diameter (diagonal length) of the light quantity control filter.

An imaging system comprising:

• a zoom lens comprising a plurality of lens groups wherein a spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device located on an image side of the zoom lens, wherein:
• the aperture stop has a fixed shape, and a shutter is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located,
• the zoom lens comprises at least a first lens group having negative refracting power and a second lens group having positive refracting power, located just after the first lens group,
• a spacing between the first lens group having negative refracting power and the second lens group having positive refracting power becomes narrower at a telephoto end than at a wide-angle end of the zoom lens,
• the aperture stop is located between a surface in the first lens group having negative refracting power, said surface being located nearest to an image side of the zoom lens, and an image side-surface in the second lens group having positive refracting power,
• the shutter is located on the image plane side with respect to the aperture stop,
• when the focal length is varied, the aperture stop is moved with the second lens group, and
• the imaging system constantly satisfies condition (3):
• 0.01<α′/β′<1.3 (3)
• where α′ is an axial distance from the aperture stop to the shutter located on an image side with respect thereto, and β′ is an axial distance from the shutter to the image pickup plane of the electronic image pickup device.

An imaging system comprising:

• a zoom lens comprising a plurality of lens groups wherein a spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device located on an image side of the zoom lens, wherein:
• the aperture stop has a fixed shape, and a shutter is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located,
• the zoom lens comprises at least a first lens group having negative refracting power and a second lens group having positive refracting power, located just after the first lens group,
• a spacing between the first lens group having negative refracting power and the second lens group having positive refracting power becomes narrower at a telephoto end than at a wide-angle end of the zoom lens,
• the aperture stop is located between a surface in the first lens group having negative refracting power, said surface being located nearest to an image side of the zoom lens, and an image side-surface in the second lens group having positive refracting power,
• the shutter is located on the image plane side with respect to the aperture stop,
• when the focal length is varied, the aperture stop is moved with the second lens group, and
• the imaging system satisfies condition (4):
• 0.5<φβ′/φα′<1.5 (4)
• where φα′ is a maximum diameter of the aperture in the aperture stop and φβ′ is a maximum effective diameter (diagonal length) of the shutter.