Zoom lens and image pickup apparatus including the same
A zoom lens includes, in order from an object side to an image side: a first lens unit having a negative refractive power; and a second lens unit having a positive refractive power, the interval between the adjacent lens units varying during zooming. The configuration of the first lens unit, the focal length f 1 of the first lens unit, and the back focus Sk at the wide angle end are appropriately set.
1. A zoom lens comprising, in order from an object side to an image side: a first lens unit having a negative refractive power; and a second lens unit having a positive refractive power, an interval between adjacent lens units varying during zooming,
the first lens unit comprises at least three lenses, the first lens unit comprises a negative lens G 1 n that is made of a resin material and has an aspherical-shaped lens surface, and a positive lens G 1 p that is made of a resin material and has an aspherical-shaped lens surface,
wherein a following conditional expression is satisfied:
0.55<| f 1/ Sk|< 2.20,
where f 1 represents a focal length of the first lens unit, and Sk represents a back focus at a wide angle end.
2. The zoom lens according to claim 1 , wherein following conditional expressions are satisfied:
0.5<SG p <2.0, and
0.5<SG n <2.0,
where SGp represents a specific gravity of a material of the positive lens G 1 p , and SGn represents a specific gravity of a material of the negative lens G 1 n.
3. The zoom lens according to claim 1 , wherein following conditional expressions are satisfied:
15.0<ν p< 40.0, and
50.0<ν n< 75.0,
where νp represents an Abbe number of a material of the positive lens G 1 p , and νn represents an Abbe number of a material of the negative lens G 1 n.
4. The zoom lens according to claim 1 ,
wherein a following conditional expression is satisfied:
0.8<| fp/fn|< 1.2,
where fp represents a focal length of the positive lens G 1 p , and fn represents a focal length of the negative lens G 1 n.
5. The zoom lens according to claim 1 ,
wherein following conditional expressions are satisfied:
1.6<| fp/f 1|<2.5, and
1.5< fn/f 1<2.5,
where f 1 represents a focal length of the first lens unit, fp represents a focal length of the positive lens G 1 p , and fn represents a focal length of the negative lens G 1 n.
6. The zoom lens according to claim 1 ,
wherein a following conditional expression is satisfied:
1.45<Nave<1.65,
where Nave represents an average value of refractive indices of materials of lenses included in the first lens unit.
7. The zoom lens according to claim 1 ,
wherein the first lens unit comprises a meniscus-shaped negative lens G 1 closest to the object side, and a following conditional expression is satisfied:
1.45<NG1<1.70,
where NG 1 represents a refractive index of a material of the negative lens G 1 .
8. The zoom lens according to claim 1 ,
wherein on the object side of the lens that is made of the resin material and included in the first lens unit, a meniscus-shaped negative lens made of a glass material is included.
9. The zoom lens according to claim 1 , wherein the first lens unit consists of, in order from the object side to the image side: a meniscus-shaped negative lens G 1 made of a glass material; an negative lens G 2 that is made of a resin material and has an aspherical-shaped lens surface; and a positive lens G 3 that is made of a resin material and has an aspherical-shaped lens surface, and the negative lens G 2 is the negative lens G 1 n , and the positive lens G 3 is the positive lens G 1 p.
10. The zoom lens according to claim 1 , wherein the zoom lens consists of, in order from the object side to the image side: a first lens unit having a negative refractive power; and a second lens unit having a positive refractive power.
11. The zoom lens according to claim 1 , wherein the zoom lens consists of, in order from the object side to the image side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a positive refractive power.
12. The zoom lens according to claim 1 , wherein the zoom lens consists of, in order from the object side to the image side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; a third lens unit having a negative refractive power; and a fourth lens unit having a positive refractive power.
13. The zoom lens according to claim 1 , wherein the zoom lens consists of, in order from the object side to the image side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; a third lens unit having a negative refractive power; a fourth lens unit having a positive refractive power; a fifth lens unit having a negative refractive power; and a sixth lens unit having a positive refractive power.
14. An image pickup apparatus, comprising:
a zoom lens; and
an image pickup element configured to receive an image formed by the zoom lens,
the zoom lens comprising, in order from an object side to an image side: a first lens unit having a negative refractive power; and a second lens unit having a positive refractive power,
wherein intervals between adjacent lens units vary during zooming,
the first lens unit comprises at least three lenses, the first lens unit comprises a negative lens G 1 n that is made of a resin material and has an aspherical-shaped lens surface, and a positive lens G 1 p that is made of a resin material and has an aspherical-shaped lens surface, and
a following conditional expression is satisfied:
0.55<| f 1/ Sk|< 2.20,
where f 1 represents a focal length of the first lens unit, and Sk represents a back focus at a wide angle end.