Imaging apparatus

1. An imaging apparatus configured to form an image on an image pickup element, the imaging apparatus comprising, in order from an object side to an image side:

a first optical unit having a negative refractive power;

a second optical unit having a positive refractive power; and

a third optical unit including the image pickup element,

wherein the first optical unit does not move during zooming,

wherein the second optical unit moves toward the object side during zooming from a wide-end angle end to a telephoto end,

wherein the third optical unit moves during zooming,

wherein the second optical unit includes an aperture stop, a positive lens having convex surfaces on both sides, a negative lens having concave surfaces on both sides, and a positive lens having a convex surface on the object side, which are arranged in order from an object side to an image side, and

wherein a focal length of the first optical unit (F 1 ), a combined focal length of the second optical unit and the third optical unit at a wide-angle end (FR), and a focal length of an entire optical system at the wide-angle end (Fw) satisfy the following conditions:

0.25< |Fw/F 1|<0.6 (where F1<0), and

0.25 <Fw/FR< 0.9.

2. The imaging apparatus according to claim 1 , wherein the third optical unit includes a lens member having a refractive power.

3. The imaging apparatus according to claim 1 , wherein the third optical unit includes the image pickup element and an optical member having no refractive power.

4. The imaging apparatus according to claim 1 , wherein the first optical unit includes a reflective member configured to fold an optical axis.

5. The imaging apparatus according to claim 1 , wherein a lens member having a refractive power is disposed within a distance of 1.5×LD in terms of air-converted length from the image pickup element, where (LD) denotes a diagonal length of an effective area of the image pickup element.

6. The imaging apparatus according to claim 5 , wherein the lens member comprises a lens having a positive refractive power and satisfies the following condition:

0.12 <Fw/PFL< 0.5,

where (PFL) denotes a focal length of the lens having a positive refractive power and (Fw) denotes a focal length of an entire optical system at a wide-angle end.

7. The imaging apparatus according to claim 5 , wherein the lens member comprises a lens having a negative refractive power and including an aspherical surface.

8. An imaging apparatus configured to form an image on an image pickup element, the imaging apparatus comprising, in order from an object side to an image side:

a first optical unit having a negative refractive power;

a second optical unit having a positive refractive power; and

a third optical unit including the image pickup element,

wherein the first optical unit does not move during zooming,

wherein the second optical unit moves toward the object side during zooming from a wide-end angle end to a telephoto end,

wherein the third optical unit moves during zooming,

wherein the second optical unit includes an aperture stop, a positive lens having convex surfaces on both sides, a negative lens having concave surfaces on both sides, and a positive lens having a convex surface on the object side, which are arranged in order from an object side to an image side, and

wherein a lens member having a refractive power is disposed within a distance of 1.5×LD in terms of air-converted length from the image pickup element, where (LD) denotes a diagonal length of an effective area of the image pickup element.

9. The imaging apparatus according to claim 8 , wherein the lens member comprises a lens having a positive refractive power and satisfies the following condition:

0.12 <Fw/PFL< 0.5,

where (PFL) denotes a focal length of the lens having a positive refractive power and (Fw) denotes a focal length of an entire optical system at a wide-angle end.

10. The imaging apparatus according to claim 8 , wherein the lens member comprises a lens having a negative refractive power and including an aspherical surface.

11. An imaging apparatus configured to form an image on an image pickup element, the imaging apparatus comprising, in order from an object side to an image side:

a first optical unit having a negative refractive power;

a second optical unit having a positive refractive power; and

a third optical unit including the image pickup element,

wherein the first optical unit does not move during zooming,

wherein the second optical unit moves toward the object side during zooming from a wide-end angle end to a telephoto end,

wherein the third optical unit moves during zooming,

wherein the second optical unit includes an aperture stop, a positive lens having convex surfaces on both sides, a positive lens, and a negative lens, which are arranged in order from an object side to an image side, and

wherein a focal length of the first optical unit (F 1 ), a combined focal length of the second optical unit and the third optical unit at a wide-angle end (FR), and a focal length of an entire optical system at the wide-angle end (Fw) satisfy the following conditions:

0.25 <|Fw/F 1|0.6 (where F1<0), and

0.25 <Fw/FR< 0.9.

12. An imaging apparatus configured to form an image on an image pickup element, the imaging apparatus comprising, in order from an object side to an image side:

a first optical unit having a negative refractive power;

a second optical unit having a positive refractive power; and

a third optical unit including the image pickup element,

wherein the first optical unit does not move during zooming,

wherein the second optical unit moves toward the object side during zooming from a wide-end angle end to a telephoto end,

wherein the third optical unit moves during zooming,

wherein the second optical unit includes an aperture stop, a positive lens having convex surfaces on both sides, a positive lens, and a negative lens, which are arranged in order from an object side to an image side, and

wherein a lens member having a refractive power is disposed within a distance of 1.5×LD in terms of air-converted length from the image pickup element, where (LD) denotes a diagonal length of an effective area of the image pickup element.

13. An imaging apparatus configured to form an image on an image pickup element, the imaging apparatus consisting of, in order from an object side to an image side:

a first optical unit having a negative refractive power;

a second optical unit having a positive refractive power; and

a third optical unit including the image pickup element,

wherein the first optical unit does not move during zooming,

wherein the second optical unit moves toward the object side during zooming from a wide-end angle end to a telephoto end,

wherein the third optical unit moves during zooming, and

wherein a focal length of the first optical unit (F 1 ), a combined focal length of the second optical unit and the third optical unit at a wide-angle end (FR), and a focal length of an entire optical system at the wide-angle end (Fw) satisfy the following conditions:

0.25 <|Fw/F 1|0.6 (where F1<0), and

0.25 <Fw/FR< 0.9.

14. An imaging apparatus configured to form an image on an image pickup element, the imaging apparatus consisting of, in order from an object side to an image side:

a first optical unit having a negative refractive power;

a second optical unit having a positive refractive power; and

a third optical unit including the image pickup element,

wherein the first optical unit does not move during zooming,

wherein the second optical unit moves toward the object side during zooming from a wide-end angle end to a telephoto end,

wherein the third optical unit moves during zooming, and

wherein a lens member having a refractive power is disposed within a distance of 1.5×LD in terms of air-converted length from the image pickup element, where (LD) denotes a diagonal length of an effective area of the image pickup element.