Patent ID: 11860347
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 7:
8. An image pickup apparatus comprising:
a zoom lens; and
an image pickup element configured to pick up an image formed by the zoom lens,
wherein the zoom lens includes in order from an object side to an image side:
a first lens unit configured not to move for zooming,
a plurality of zooming lens units configured to move in zooming,
a front relay lens unit configured not to move for zooming,
an extender lens unit insertable into and removable from an optical path for changing a focal length range of the zoom lens, and
a rear relay lens unit configured not to move for zooming,
wherein a part of the first lens unit moves at focusing,
a combined focal length of the front relay lens unit, the extender lens unit and the rear relay lens unit is a positive value,
wherein following conditional expressions are satisfied:

1.00 <(Def/Der)/βe+(1−few/feF)<1.75,

0.50<(le/Der)/βe<1.22, and

0.10<few/feF<1.00,

where few is a focal length at a wide-angle end and in a state where the extender lens unit is inserted, feF is a combined focal length from the first lens unit to the front relay lens unit, Def is an effective diameter of a lens surface in a lens included in the extender lens unit and closest to the object side, Der is an effective diameter of a lens surface in a lens included in the extender lens unit and closest to the image side, βe is a lateral magnification of the extender lens unit, and le is a distance on an optical axis from a surface included in the extender lens unit and closest to the object side to a surface included in the extender lens unit and closest to the image side.