A zoom lens includes, in order from an object side, a first lens group fixed upon zooming and wholly having a negative refractive power, a second lens group formed by an optical-path bending prism fixed upon zooming and, a third lens group allowed to move upon zooming and wholly having a positive refractive power, a fourth lens group allowed to move upon zooming and wholly having a negative refractive power, and a fifth lens group fixed upon zooming and wholly having a positive refractive power. By arranging a zooming group having the positive third and negative fourth lens groups without arranging a positive fixed lens group in back of the prism, the overall length can be easily reduced as compared to the structure arranging a fixed lens group between a prism and a zooming group.
1. A zoom lens comprising, in order from an object side:
a first lens group that is fixed upon zooming and wholly has a negative refractive power;
a second lens group that comprises an optical path bending prism, the second lens group which is fixed upon zooming;
a third lens group that is allowed to move upon zooming and wholly has a positive refractive power;
a fourth lens group that is allowed to move upon zooming and wholly has a negative refractive power; and
a fifth lens group that is fixed upon zooming and wholly has a positive refractive power,
wherein the following Conditional Expressions (1) to (2) are satisfied:
−1.5< f 3/ f 4<−0.5 (1)
2.0< DA/f w <3.0 (2)
where
f 3 denotes focal length of the third lens group,
f 4 denotes focal length of the fourth lens group,
f w denotes focal length of a system overall at a wide end, and
DA denotes optical path length from an image-side surface of the first lens group to an object-side surface of the third lens group, at a telephoto end.
2. The zoom lens of claim 1 ,
wherein the first lens group comprises a negative aspheric lens having a concave surface directed toward an image side,
the third lens group comprises at least a positive lens having a convex surface directed toward the object side,
the fourth lens group comprises at least a negative lens having a concave surface directed toward the image side, and
the fifth lens group comprises a positive aspheric lens having a convex surface directed toward the image side.
3. The zoom lens of claim 1 ,
wherein further satisfying the following Conditional Expression (3):
50<νG3 (3)
where
νG 3 : mean value of Abbe numbers at d-line over lenses in the third lens group.
4. The zoom lens of claim 1 ,
wherein the fourth lens group comprises a cemented lens that includes two lenses; and a negative lens having a concave surface directed toward the image side.
5. The zoom lens of claim 1 ,
wherein the fourth lens group comprises (i) a cemented lens that includes a positive lens and a first negative lens, and (ii) a second negative lens, and
wherein the first negative lens has a concave surface directed toward the image side.
6. The zoom lens in claim 1 ,
wherein the third lens group comprises two spherical lenses.
7. The zoom lens in claim 1 ,
wherein the third lens group comprises (i) a positive aspheric lens at both surfaces, the positive aspheric lens having a convex surface directed toward the object side and (ii) a spherical lens.
8. The zoom lens of claim 1 ,
wherein the first lens group comprises a negative aspheric lens having a concave surface directed toward an image side,
the third lens group comprises at least a positive lens having a convex surface directed toward the object side,
the fourth lens group comprises at least a negative lens having a concave surface directed toward the image side, and
the fifth lens group comprises a positive aspheric lens having a convex surface directed toward the image side.
9. A zoom lens comprising, in order from an object side:
a first lens group that is fixed upon zooming and wholly has a negative refractive power;
a second lens group that comprises an optical path bending prism, the second lens group which is fixed upon zooming;
a third lens group that is allowed to move upon zooming and wholly has a positive refractive power;
a fourth lens group that is allowed to move upon zooming and wholly has a negative refractive power, wherein the fourth lens group includes at least two lenses; and
a fifth lens group that is fixed upon zooming and wholly has a positive refractive power.
10. The zoom lens of claim 9 ,
wherein the first lens group comprises a negative aspheric lens having a concave surface directed toward an image side,
the third lens group comprises at least a positive lens having a convex surface directed toward the object side,
the fourth lens group comprises at least a negative lens having a concave surface directed toward the image side, and
the fifth lens group comprises a positive aspheric lens having a convex surface directed toward the image side.
11. The zoom lens of claim 9 ,
wherein the fourth lens group comprises a cemented lens that includes two lenses; and a negative lens having a concave surface directed toward the image side.
12. A zoom lens comprising, in order from an object side:
a first lens group that is fixed upon zooming and wholly has a negative refractive power;
a second lens group that comprises an optical path bending prism, the second lens group which is fixed upon zooming;
a third lens group that is allowed to move upon zooming and wholly has a positive refractive power;
a fourth lens group that is allowed to move upon zooming and wholly has a negative refractive power; and
a fifth lens group that is fixed upon zooming and wholly has a positive refractive power,
wherein the following Conditional Expression (3) is satisfied:
50<νG3 (3)
where
νG 3 : mean value of Abbe numbers at d-line over lenses in the third lens group.
13. The zoom lens of claim 12 ,
wherein the first lens group comprises a negative aspheric lens having a concave surface directed toward an image side,
the third lens group comprises at least a positive lens having a convex surface directed toward the object side,
the fourth lens group comprises at least a negative lens having a concave surface directed toward the image side, and
the fifth lens group comprises a positive aspheric lens having a convex surface directed toward the image side.
14. The zoom lens of claim 12 ,
wherein the fourth lens group comprises a cemented lens that includes two lenses; and a negative lens having a concave surface directed toward the image side.