Zoom lens and image pickup apparatus
AssigneeCanon Kabushiki Kaisha
InventorsMasao Hori, Naotoshi Ogawa
Life of this patent
Estimating the term…
Abstract
Provided is a zoom lens including, in order from object side: a positive first unit configured not to be moved for zooming; one or two negative second units configured to be moved for zooming; a stop configured to reduce an outer part of an off-axis light; two or three third units configured to be moved for zooming; and a fourth unit, in which focal lengths of the first unit and the second units, a distance on an optical axis from the stop to a vertex of a surface closest to the object side in the third units under a zoom state in which F-drop starts, and a distance on the optical axis from a vertex of a surface closest to the image side in the second units to the vertex of the surface closest to the object side in the third units under the zoom state are appropriately set.
Claims12
A zoom lens comprising in order from an object side to an image side:
- a first lens unit having a positive refractive power and configured not to be moved for zooming;
- one or two second lens units having a negative refractive power and configured to be moved for zooming;
- a stop configured to reduce an outer part of an off-axial light;
- two or three third lens units configured to be moved for zooming;
- and
- a fourth lens unit,
- wherein conditional expressions
- −13.0≤f1/f2≤−5.0;
- and
- 0.26≤Xi3/S23≤0.46
- are satisfied where f1 represents a focal length of the first lens unit, f2 represents a focal length of the one or two second lens units, Xi3 represents a distance on an optical axis from the stop to a vertex of a surface closest to the object side in the two or three third lens units at a zoom state in which F-drop starts, and S23 represents a distance on the optical axis from a vertex of a surface closest to the image side in the one or two second lens units to the vertex of the surface closest to the object side in the two or three third lens units at the zoom state.
An image pickup apparatus comprising:
- a zoom lens comprising in order from an object side to an image side:
- a first lens unit having a positive refractive power and configured not to be moved for zooming;
- one or two second lens units having a negative refractive power and configured to be moved for zooming;
- a stop configured to reduce an outer part of an off-axial light;
- two or three third lens units configured to be moved for zooming;
- and
- a fourth lens unit,
- wherein conditional expressions
- −13.0≤f1/f2≤−5.0;
- and
- 0.26≤Xi3/S23≤0.46
- are satisfied where f1 represents a focal length of the first lens unit, f2 represents a focal length of the one or two second lens units, Xi3 represents a distance on an optical axis from the stop to a vertex of a surface closest to the object side in the two or three third lens units at a zoom state in which F-drop starts, and S23 represents a distance on the optical axis from a vertex of a surface closest to the image side in the one or two second lens units to the vertex of the surface closest to the object side in the two or three third lens units at the zoom state;
- and
- an image pickup element configured to receive an image formed by the zoom lens.
Dependencies are inferred from the claim text.