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US 6,639,721 B2Granted
Zoom lens system and optical apparatus using the same
AssigneeCanon Kabushiki Kaisha
InventorHiroshi Endo
Life of this patent
Estimating the term…
Abstract
There are provided A zoom lens system comprising, in order from an object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power, and a fourth lens unit of positive refractive power, wherein the zoom lens system zooming from a wide angle end to a telephoto end a separation between each lens units is varied so that conditional expressions D1W>D1T, D2W>D2T, and D3W>D3T are satisfied where DiW is a separation between an i-th lens unit and an (i+1)-th lens unit at a wide-angle end, DiT is a separation between an i-th lens unit and an (i+1)-th lens unit at a telephoto end, wherein a diffraction optical element is included in at least one of lens units.
Claims14
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-anile end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end, and
- wherein a diffraction optical element is included in the fourth lens unit, and a conditional expression
- 15<f4DOE /ft<1500 is satisfied
- where f4DOE is a focal length of only a diffraction component of the diffraction optical element, and ft is a focal length of an entire lens system at the telephoto end.
5 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-angle end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end, and
- wherein a diffraction optical element is included in the first lens unit, and a conditional expression
- −1500<f1DOE /ft<−15 is satisfied
- where f1DOE is a focal length of only a diffraction component of the diffraction optical element and ft is a focal length of an entire lens system at the telephoto end.
5 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-angle end DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end,
- wherein a diffraction optical element is included in at least one of said lens units, and wherein conditional expressions 0.7<|f1|/{square root over ((fw·ft))}<1.1, 0.6<f2/{square root over ((fw·ft))}<1.4, 1.05<|f3|/f2<1.5, and 1.05<f4/f2<2.5 are satisfied where fw and ft are focal lengths of an entire lens system at the wide-angle and telephoto ends, respectively, and fi is a focal length of the i-th lens unit.
3 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power, wherein said first lens unit has such an aspheric surface that negative refractive power of the aspheric surface decreases from a center of the lens to a peripheral of the lens,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-angle end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end,
- wherein a diffraction optical element is included in at least one of said lens units.
3 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-angle end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end,
- wherein a diffraction optical element is included in at least one of said lens units, and
- wherein a conditional expression −30<θ<30 is satisfied where θ is an angle between a ray incident to and emitted from said diffraction optical element and a plane normal of said diffraction optical element.
4 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power, wherein said fourth lens unit has such an aspheric surface that positive refractive power of the aspheric surface decreases from a center of the lens to a peripheral of the lens,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-angle end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end,
- wherein a diffraction optical element is included in at least one of said lens units.
3 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide-angle end to a telephoto end while varying a separation between each lens units so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between i-th and (i+1)-th lens units at a wide-angle end, DiT is a separation between the i-th and (i+1)-th lens units at a telephoto end,
- wherein a diffraction optical element is included in at least one of said lens units, and
- wherein a conditional expression |dQ(h)/dh|<30 is satisfied where Ci is a phase coefficient, h is a height from a center of an optical axis, λo is a reference wave length, and Q(h)=(C1·h2+C2·h4+C3·h6+ . . . )/λo.
4 more elements
An optical apparatus comprising a zoom lens system comprising, in order from an object side,
- a first lens unit of negative refractive power,
- a second lens unit of positive refractive power,
- a third lens unit of negative refractive power, and
- a fourth lens unit of positive refractive power,
- wherein said zoom lens system zooming from a wide angle end to a telephoto end a separation between each lens units is varied so that conditional expressions D1W>D1T, D2W<D2T, and D3W>D3T are satisfied where DiW is a separation between an i-th lens unit and an (i+1)-th lens unit at a wide-angle end, DiT is a separation between an i-th lens unit and an (i+1)-th lens unit at a telephoto end,
- wherein a diffraction optical element is included in at least one of lens units, and
- wherein a conditional expression −30<θ<30 is satisfied where θ is an angle between a ray incident to and emitted from said diffraction optical element and a plane normal of said diffraction optical element.
4 more elements
Dependencies are inferred from the claim text.