JP2009288300A5

JP2009288300A5 -

Info

Publication number: JP2009288300A5
Application number: JP2008137991A
Authority: JP
Filing date: 2008-05-27
Publication date: 2010-07-22
Anticipated expiration: 2028-05-27

Claims

From the object side, the first lens with negative power, the second lens with negative power, the third lens, the fourth lens with positive power, the fifth lens with positive power, the first lens with negative power 6 lenses in this order,
The second lens to the sixth lens are such that at least one lens surface of each lens forms an aspheric surface,
The imaging lens, wherein the third lens and the sixth lens are made of a material having an Abbe number of 45 or less with respect to the d-line.

From the object side,
A first lens that is a meniscus lens having negative power and a concave surface facing the image side;
At least the image-side lens surface is an aspherical surface, the center portion of the lens surface is a concave surface, and the effective diameter peripheral portion is a second lens having a weaker negative power than the center portion;
A third lens in which at least one lens surface is aspheric;
A fourth lens having positive power and at least one lens surface being aspheric;
A fifth lens having positive power and at least one lens surface being aspheric;
An imaging lens comprising a sixth lens having negative power and at least one lens surface being an aspherical surface in this order.

The imaging lens according to claim 1, wherein a diaphragm is disposed between the third lens and the fourth lens.

4. The imaging lens according to claim 1, wherein the third lens has a positive power, and a central portion of a lens surface on the object side forms a convex surface. 5.

The imaging lens according to claim 1, wherein the following conditional expression (1) is satisfied.
2.0 <f56 / f <5.5 (1)
However,
f: focal length of the entire imaging lens system f56: combined focal length of the fifth lens and the sixth lens

The imaging lens according to claim 1, wherein the following conditional expression (2) is satisfied.
2.5 <(D4 + D5) / f <5.5 (2)
However,
f: Focal length D4 of the entire imaging lens system D: Air distance between the second lens and the third lens D5: Center thickness of the third lens

The imaging lens according to claim 1, wherein the following conditional expression (3) is satisfied.
4.0 <f3 / f <9.0 (3)
However,
f: focal length of the entire imaging lens system f3: focal length of the third lens

8. The lens surface on the image side of the second lens, wherein the central portion of the lens surface is a concave surface, and the peripheral portion of the effective diameter is weaker in negative power than the central portion. The imaging lens according to any one of the above.

The lens surface on the object side of the second lens has a convex surface at the center of the lens surface, and the peripheral edge portion of the effective diameter has a weaker positive power than the central portion, or the central portion of the lens surface has a convex surface and is effective The imaging lens according to any one of claims 1 to 8, wherein the radial peripheral portion has negative power.

The lens surface on the object side of the third lens has a convex portion at the center of the lens surface, and has a region having a positive power stronger than the center within the effective diameter. The imaging lens according to any one of the above.

11. The lens surface on the image side of the fifth lens, wherein the central portion of the lens surface is convex, and the peripheral portion of the effective diameter has a positive power weaker than that of the central portion. The imaging lens according to any one of the above.

12. The lens surface on the object side of the sixth lens, wherein the central portion of the lens surface is a concave surface, and the peripheral portion of the effective diameter is weaker in negative power than the central portion. The imaging lens according to any one of the above.

The lens surface on the image side of the sixth lens is such that the central portion of the lens surface is convex, and the peripheral portion of the effective diameter is weaker in positive power than the central portion. The imaging lens according to any one of the above.

The imaging lens according to claim 1, wherein the following conditional expression (4) is satisfied.
11 <L / f <18 (4)
However,
f: Focal length of the entire imaging lens system
L : Distance from the object-side lens surface of the first lens to the imaging plane

15. An imaging apparatus comprising: the imaging lens according to claim 1; and an imaging element that converts an optical image formed by the imaging lens into an electrical signal.