Plastic lens and lens barrel

1. A plastic lens comprising:

two lens surfaces, the two lens surfaces including a first surface and a second surface that opposes the first surface;

a first edge section having a first outer circumferential edge surface formed substantially parallel to an optical axis of the plastic lens; and

a second edge section having a second outer circumferential edge surface that is formed so as to have a step with respect to the first outer circumferential edge surface, and that is formed substantially parallel to the optical axis of the plastic lens, wherein

the first edge section and the second edge section are located outside of a longer lens surface among the two lens surfaces in a radial direction from the optical axis of the plastic lens,

the first outer circumferential edge surface is not coated with a black coating material that suppresses internal reflection of light,

at least a portion of the second outer circumferential edge surface is coated with the black coating material that suppresses internal reflection of light,

the first edge section is held by a holding section,

the second edge section is not held by the holding section, and

the plastic lens satisfies the following condition (1):

0.1< D 2− D 1<2.0  (1)

where

D 1 is a diameter (mm) of the plastic lens at the first edge section, and

D 2 is a diameter (mm) of the plastic lens at the second edge section.

2. The plastic lens as claimed in claim 1 , wherein

a surface opposite to a light-incident side is a concave surface, and

the second outer circumferential edge surface is formed at a position closer to the light-incident side than the first outer circumferential edge surface.

3. The plastic lens as claimed in claim 1 ,

being formed by injection molding, and

having, on the second outer circumferential edge surface, a gate trace that has been formed when a lens material injected into a mold from a gate section at the time of the injection molding was solidified in the gate section.

4. A lens barrel, comprising:

a plastic lens; and

a holding section that holds at least the plastic lens, wherein the plastic lens comprises:

two lens surfaces, the two lens surfaces including a first surface and a second surface that opposes the first surface;

a first edge section having a first outer circumferential edge surface formed substantially parallel to an optical axis of the plastic lens; and

a second edge section having a second outer circumferential edge surface that is formed so as to have a step with respect to the first outer circumferential edge surface, and that is formed substantially parallel to the optical axis of the plastic lens, wherein

the first edge section and the second edge section are located outside of a longer lens surface among the two lens surfaces in a radial direction from the optical axis of the plastic lens,

the first outer circumferential edge surface is not coated with a black coating material that suppresses internal reflection of light,

at least a portion of the second outer circumferential edge surface is coated with the black coating material that suppresses internal reflection of light,

the plastic lens is held by the holding section at the first edge section,

the plastic lens is not held by the holding section at the second edge section, and

the plastic lens satisfies the following condition (1):

0.1< D 2− D 1<2.0  (1)

where

D 1 is a diameter (mm) of the plastic lens at the first edge section, and

D 2 is a diameter (mm) of the plastic lens at the second edge section.

5. The lens barrel as claimed in claim 4 , comprising, in order from an object side to an image side, at least a lens and the plastic lens, wherein

the lens is held by the holding section.