Wide-angle zoom lens
AssigneeCanon Kabushiki Kaisha
InventorHiroshi Endo
Life of this patent
Estimating the term…
Abstract
A zoom lens is disclosed comprising, from front to rear, 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, zooming being performed by varying the separations between these lens units, and the zoom lens satisfying the following conditions: -0.3<M1/M2<1.0 6.0<TLW/fW<10.0 where fW is the shortest focal length of the entire system, M1 and M2 are the total zooming movements of the first and second lens units, respectively, and TLW is the optical total length for the wide-angle end.
Claims6
A zoom lens, comprising, from front to rear, 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 zooming is effected by changing spaces between said lens units, and said first lens unit has, from front to rear, a negative lens, a negative lens, and a positive lens, and at least one non-spherical lens surface which shows a positive refractive power increasing from center to periphery, and said fourth lens unit has at least one non-spherical lens surface which shows a positive refractive power decreasing from center to periphery, and which satisfies the following conditions:
- D1T<D1W
- D2W<D2T
- D3T<D3W,
- wherein for said first to fourth lens units, DiW denotes the axial air separation for the wide-angle end between the i-th and the (i+1)st lens units, and DiT denotes the axial air separation for the telephoto end between the i-th and the (i+1)st lens unit.
A zoom lens, comprising, from front to rear, 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 zooming is effected by changing spaces between said lens units, and said fourth lens unit has a positive sub-lens unit, a second sub-lens unit of a meniscus lens having a strong negative refractive power on the image side, and a third positive sub-lens unit and has at least one non-spherical lens surface which shows a positive refractive power decreasing from center to periphery, and which satisfies the following conditions:
- D1T<D1W
- D2W<D2T
- D3T<D3W,
- wherein for said first to fourth lens units, DiW denotes the axial air separation for the wide-angle end between the i-th and the (i+1)st lens units, and DiT denotes the axial air separation for the telephoto end between the i-th and the (i+1)st lens unit.
Dependencies are inferred from the claim text.