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US 6,785,055 B2Granted
Zoom lens system
AssigneeMinolta Co., Ltd.
InventorsJun Nishikawa, Tomoko Nakagawa
Life of this patent
Estimating the term…
Abstract
A zoom lens system has, in order from an enlargement side, a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having positive optical power, a fourth lens unit having negative optical power, including an aperture stop, a fifth lens unit having positive or negative optical power, and a sixth lens unit having positive optical power. Zooming is achieved by varying the first to fifth variable distances between the lens units. The third and fifth lens units move from the enlargement side to the reduction side during zooming from the telephoto end to the wide-angle end. The zoom lens system is substantially telecentric toward the reduction side.
Claims19
A zoom lens system comprising, from an enlargement side:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power and disposed on an image side of the first lens unit with a first variable distance secured in between;
- a third lens unit having a positive optical power and disposed on an image side of the second lens unit with a second variable distance secured in between;
- a fourth lens unit having a negative optical power and disposed on an image side of the third lens unit with a third variable distance secured in between, the fourth lens unit including an aperture stop;
- a fifth lens unit having a positive or negative optical power and disposed on an image side of the fourth lens unit with a fourth variable distance secured in between;
- and
- a sixth lens unit having a positive optical power and disposed on an image side of the fifth lens unit with a fifth variable distance secured in between,
- wherein zooming is achieved by varying the first to fifth variable distances,
- wherein the third and fifth lens units move from the enlargement side to a reduction side during zooming from a telephoto end to a wide-angle end, and
- wherein the zoom lens system is substantially telecentric toward the reduction side.
7 more elements
A zoom lens system comprising, from an enlargement side:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power and disposed on an image side of the first lens unit with a first variable distance secured in between;
- a third lens unit having a positive optical power and disposed on an image side of the second lens unit with a second variable distance secured in between;
- a fourth lens unit having a negative optical power and disposed on an image side of the third lens unit with a third variable distance secured in between;
- a fifth lens unit having a positive or negative optical power and disposed on an image side of the fourth lens unit with a fourth variable distance secured in between;
- and
- a sixth lens unit having a positive optical power and disposed on an image side of the fifth lens unit with a fifth variable distance secured between,
- wherein zooming is achieved by varying the first to fifth variable distances,
- wherein the third and fifth lens units move from the enlargement side to a reduction side during zooming from a telephoto end to a wide-angle end,
- wherein the zoom lens system is substantially telecentric toward the reduction side, and
- wherein the distance between the first and second lens units decreases during zooming from the telephoto end the wide-angle end.
8 more elements
A zoom lens system comprising, from an enlargement side:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power and disposed on an image side of the first lens unit with a first variable distance secured in between;
- a third lens unit having a positive optical power and disposed on an image side of the second lens unit with a second variable distance secured in between;
- a fourth lens unit having a negative optical power and disposed on an image side of the third lens unit with a third variable distance secured in between;
- a fifth lens unit having a positive or negative optical power and disposed on an image side of the fourth lens unit with a fourth variable distance secured in between;
- and
- a sixth lens unit having a positive optical power and disposed on an image side of the fifth lens unit with a fifth variable distance secured in between,
- wherein zooming is achieved by varying the first to fifth variable distances,
- wherein the third and fifth lens units move from the enlargement side to a reduction side during zooming from a telephoto end to a wide-angle end,
- wherein the zoom lens system is substantially telecentric toward the reduction side, and
- wherein the fifth lens unit includes at least one positive lens element that fulfills the following conditional formulae:
- 0.7<ΔP5<6.0 (11)
- 60<ν(5) <100 (12)
- where
- ΔP5=[Θ−(0.6444−0.001689)·ν(5)]×100;
- Θ=(ng−nF)/(nF−nC);
- ng represents a refractive index for a g-line (having a wavelength of 435.84 nm);
- nF represents a refractive index for an F-line (having a wavelength of 486.13 nm);
- nd represents a refractive index for a d-line (having a wavelength of 587.56 nm);
- nC represents a refractive index for a C-line (having a wavelength of 656.28 nm);
- ν(5) represents an Abbe number vd of the positive lens element included in the fifth lens unit;
- and
- νd=(nd−1)/(nF−nC).
20 more elements
A zoom lens system comprising, from an enlargement side:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power and disposed on an image side of the first lens unit with a first variable distance secured in between;
- a third lens unit having a positive optical power and disposed on an image of the second lens unit with a second variable distance secured in between;
- a fourth lens unit having a negative optical power and disposed on an image side of the third lens unit with a third variable distance secured in between;
- a fifth lens unit having a positive or negative optical power and disposed on an image side of the fourth lens unit with a fourth variable distance secured in between;
- and
- a sixth lens unit having a positive optical power and disposed on an image side of the fifth lens unit with a fifth variable distance secured in between,
- wherein zooming is achieved by varying the first to fifth variable distances,
- wherein the third and fifth lens units move from the enlargement side to a reduction side during zooming from a telephoto end to a wide-angle end,
- wherein the zoom lens system is substantially telecentric toward the reduction side, and
- wherein the first lens unit includes at least one aspherical surface on a negative lens element.
8 more elements
A zoom lens system comprising,:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power and disposed on an image side of the first lens unit with a first variable distance secured in between;
- a third lens unit having a positive optical power and disposed on an image side of
- the second lens unit with a second variable distance secured in between;
- a fourth lens unit having a negative optical power and disposed on an image side of the third lens unit with a third variable distance secured in between;
- a fifth lens unit having a positive or negative optical power and disposed on an image side of the fourth lens unit with a fourth variable distance secured in between;
- and
- a sixth lens unit having a positive optical power and disposed on an image side of the fifth lens unit with a fifth variable distance secured in between,
- wherein zooming is achieved by varying the first to fifth variable distances,
- wherein the third and fifth lens units move from the enlargment side to a reduction side during zooming from a telephoto end to a wide-angle end,
- wherein the zoom lens system is substantially telecentric toward the reduction side, and
- wherein the fourth lens unit includes at least one aspherical surface.
9 more elements
A zoom lens system comprising, from an enlargement size:
- a first lens unit having a negative optical power;
- a second lens unit having a positive optical power and disposed on an image side of the first lens unit with a first variable distance secured in between;
- a third lens unit having a positive optical power and disposed on an image side of the second lens unit with a second variable distance secured in between;
- a fourth lens unit having a negative optical power and disposed on an image side of the third lens unit with a third variable distance secured in between;
- a fifth lens unit having a positive or negative optical power and disposed on an image side of the fourth lens unit with a fourth variable distance secured in between;
- and
- a sixth lens unit having a positive optical power and disposed on an image side of the fifth lens unit with a fifth variable distance secured in between,
- wherein zooming is achieved by varying the first to fifth variable distances,
- wherein the third and fifth lens units move from the enlaregment side to a reduction side during zooming from a telephoto end to a wide-angle end,
- wherein the zoom lens system is substantially telecentric toward the reduction side, and
- wherein a most enlargement-side lens element of the first lens unit has a negative optical power.
8 more elements
Dependencies are inferred from the claim text.