Zoom lens
AssigneeSamsung Aerospace Industries, Ltd.
InventorGeon-Mo Kang
Life of this patent
Estimating the term…
Abstract
A zoom lens system using inexpensive lens materials and having a high magnification zoom ratio of more than 2 times and good aberration performance. A first lens group has a positive refractive power, and a second lens group has a negative refractive power. The distance between the first lens group and the second lens group varies during zooming. 0.37<f.sub.I /(f.sub.bT -f.sub.bw)<0.7; m.sub.2T /m.sub.2w >2.0, where f.sub.I is a combined focal length of the first lens group, f.sub.bT is a back focus distance at a telephoto position f.sub.bw is a back focus distance at a wide angle position, m.sub.2T is a magnification of the second lens group at a telephoto position, and m.sub.2w is a magnification of the second lens group at a wide angle position.
Claims5
A zoom lens system, comprising:
- a first lens group having a positive refractive power;
- a second lens group having a negative refractive power, the distance between the first lens group and the second lens group being variable during zooming,
- wherein said first lens group comprises:
- a first lens having a positive refractive power with a shape of a meniscus lens convex toward an object;
- a second lens having a negative refractive power with two concave sides;
- a third lens having a positive refractive power with two convex sides;
- and
- a fourth lens having a positive refractive power with two convex sides;
- wherein said second lens group comprises:
- a fifth lens having a positive refractive power with a shape of a meniscus lens concave toward an object;
- a sixth lens having a negative refractive power with a shape of a meniscus lens;
- and
- a seventh lens having a negative refractive power;
- wherein
- 0.37<f.sub.I /(f.sub.bT -f.sub.bw)<0.7
- m.sub.2T /m.sub.2w >2.0
- where
- f.sub.1 :
- combined focal length of the first lens group,
- f.sub.bT :
- back focus distance at a telephoto position,
- f.sub.bw :
- back focus distance at a wide angle position,
- m.sub.2T :
- magnification of the second lens group at a telephoto position, and
- m.sub.2w :
- magnification of the second lens group at a wide angle position.
A zoom lens system, comprising:
- a first lens group having a positive refractive power;
- a second lens group having a negative refractive power, the distance between the first lens group and the second lens group being variable during zooming,
- wherein said first lens group comprises:
- a first lens having a positive refractive power with a shape of a meniscus lens convex toward an object;
- a second lens having a negative refractive power with two concave sides;
- a third lens having a positive refractive power with two convex sides;
- and
- a fourth lens having a positive refractive power with two convex sides;
- wherein said second lens group comprises:
- a fifth lens having a positive refractive power with a shape of a meniscus lens concave toward an object;
- a sixth lens having a negative refractive power with a shape of a meniscus lens;
- and
- a seventh lens having a negative refractive power;
- wherein
- -2. 7<N.sub.7 .upsilon..sub.7 /f.sub.7 <-1.5
- 0.5<N.sub.6 .upsilon..sub.6 /N.sub.7 f.sub.7 <1.33
- where
- N.sub.6 :
- refractive index of the sixth lens
- .upsilon..sub.6 :
- ABBE number of the sixth lens
- N.sub.7 :
- refractive index of the seventh lens
- .upsilon..sub.7 :
- ABBE number of the seventh lens
- f.sub.7 :
- focal length of the seventh lens.
Dependencies are inferred from the claim text.