Zoom lens of retrofocus type
AssigneeCanon Kabushiki Kaisha
InventorsHidemi Takayama, Hiroki Nakayama, Akihisa Horiuchi, Fumihito Wachi
Life of this patent
Estimating the term…
Abstract
A zoom lens of the retrofocus type includes, in order from a longer-distance conjugate point side to a shorter-distance conjugate point side, a front lens unit of negative refractive power, and a rear lens unit of positive refractive power, wherein a separation between the front lens unit and the rear lens unit varies according to variation of magnification, and at least one of the front lens unit and the rear lens unit is provided with a diffractive optical element.
Claims37
A zoom lens of retrofocus type, comprising, in order from a longer-distance conjugate point side to a shorter-distance conjugate point side:
- a front lens unit of negative refractive power;
- and one or more lens units, wherein said one or more lens units, taken together, have a positive refractive power, wherein a separation between said front lens unit and a most longer-distance conjugate point side lens unit of said one or more lens units varies when zooming, and at least one of said front lens unit and said one or more lens units is provided with a diffractive optical element, wherein plural lens units of said zoom lens move independently during zooming, and wherein said diffractive optical element has a positive refractive power.
Dependencies are inferred from the claim text.