Zoom lens system and projection apparatus using the same
AssigneeCanon Kabushiki Kaisha
InventorsHiroto Yasui, Fumihito Wachi
Life of this patent
Estimating the term…
Abstract
A zoom lens system which allows a reduction in size. This zoom lens makes two points at different distances have an optically conjugate relationship, and sequentially includes, from a first conjugate point side at a longer distance to a second conjugate point side at a shorter distance, a first lens unit having a negative optical power, a second lens unit, a third lens unit, a fourth lens unit, a fifth lens unit, and a sixth lens unit. A plurality of lens units of the first to sixth lens units move for zooming, and at least one lens unit of the first to sixth lens units has a diffractive optical element.
Claims36
A zoom lens system which makes two points at different distances have an optically conjugate relationship, sequentially comprising, from a first conjugate point side at a longer distance to a second conjugate point side at a shorter distance:
- a first lens unit having a negative optical power;
- a second lens unit;
- a third lens unit;
- a fourth lens unit;
- a fifth lens unit;
- and
- a sixth lens unit;
- wherein a plurality of lens units of said first to sixth lens units move for zooming,
- at least one lens unit of said first to sixth lens units has a diffractive optical element, and
- wherein said first and sixth lens units do not move for zooming.
A zoom lens system which makes two points at different distances have an optically conjugate relationship, sequentially comprising, from a first conjugate point side at a longer distance to a second conjugate point side at a shorter distance:
- a first lens unit having a negative optical power, said first lens unit not moving for zooming;
- a second lens unit having a positive optical power;
- a third lens unit having a positive optical power;
- a fourth lens unit having a negative optical power;
- a fifth lens unit having a positive optical power;
- and
- a sixth lens unit having a positive optical power, said sixth lens unit not moving for zooming,
- wherein at least three lens units of said second to fifth lens units move for zooming, and
- at least one lens unit of said first to sixth lens units has a diffractive optical element.
Dependencies are inferred from the claim text.