1. A zoom lens consisting of, in order from the object side:
a first lens group having positive refractive power, and which is fixed during magnification change;
a second lens group having negative refractive power, and which moves during magnification change;
a third lens group having positive refractive power, and which is fixed during magnification change;
a fourth lens group having positive refractive power, and which moves during magnification change; and
a fifth lens group having negative refractive power, and which moves during magnification change,
wherein the first lens group consists of, in order from the object side, a front group having negative refractive power, a reflection member that bends an optical path and a rear group having positive refractive power, and
wherein the fourth lens group includes at least a cemented lens of a positive lens and a negative lens, and
wherein the following conditional expressions (1) and (5) are satisfied:
0.8<IHfw\u2003\u2003(1); and
\u03bdd4p\u2212\u03bdd4n>45\u2003\u2003(5), where
IH is a maximum image height,
fw is a focal length at a wide angle end,
\u03bdd4p is an Abbe number of the positive lens constituting the cemented lens in the fourth lens group, and
\u03bdd4n is an Abbe number of the negative lens constituting the cemented lens in the fourth lens group.
2. The zoom lens, as defined in claim 1, wherein the third lens group includes a stop, and
wherein the following conditional expression (2) is satisfied:
0.18<\u03c6stwDstim<0.25\u2003\u2003(2), where
\u03c6stw is an aperture stop diameter at a wide angle end, and
Dstim is a distance from a stop to an image plane.
3. The zoom lens, as defined in claim 1, wherein the following conditional expression (3) is satisfied:
\u03bdd4p>75.0\u2003\u2003(3), where
\u03bdd4p is an Abbe number of the positive lens constituting the cemented lens in the fourth lens group.
4. The zoom lens, as defined in claim 1, wherein the following conditional expression (4) is satisfied:
1.5<f4fw<3.0\u2003\u2003(4), where
f4 is a focal length of the fourth lens group.
5. The zoom lens, as defined in claim 1, wherein the second lens group includes, in order from the object side, a negative lens, a positive lens and a negative lens, and consists of four lenses as a whole.
6. The zoom lens, as defined in claim 1, wherein the third lens group includes, in order from the object side, a positive lens and a negative lens.
7. The zoom lens, as defined in claim 1, wherein the following conditional expression (6) is satisfied:
\u03c6stt\u03c6stw<1\u2003\u2003(6), where
\u03c6stt is an aperture stop diameter at a telephoto end, and
\u03c6stw is an aperture stop diameter at a wide angle end.
8. The zoom lens, as defined in claim 1, wherein the following conditional expression (1-1) is satisfied:
0.8<IHfw<1.1\u2003\u2003(1-1).
9. The zoom lens, as defined in claim 1, wherein the following conditional expression (1-2) is satisfied:
0.9<IHfw<1.1\u2003\u2003(1-2).
10. The zoom lens, as defined in claim 1, wherein the third lens group includes a stop, and
wherein the following conditional expression (2-1) is satisfied:
0.18<\u03c6stwDstim<0.23\u2003\u2003(2-1), where
\u03c6stw is an aperture stop diameter at a wide angle end, and
Dstim is a distance from a stop to an image plane.
11. The zoom lens, as defined in claim 1, wherein the following conditional expression (3-1) is satisfied:
\u03bdd4p>80.0\u2003\u2003(3-1), where
\u03bdd4p is an Abbe number of the positive lens constituting the cemented lens in the fourth lens group.
12. The zoom lens, as defined in claim 1, wherein the following conditional expression (4-1) is satisfied:
1.7<f4fw<2.5\u2003\u2003(4-1), where
f4 is a focal length of the fourth lens group.
13. The zoom lens, as defined in claim 1, wherein the following conditional expression (5-1) is satisfied:
\u03bdd4p\u2212\u03bdd4n>50\u2003\u2003(5-1), where
\u03bdd4p is an Abbe number of the positive lens constituting the cemented lens in the fourth lens group, and
\u03bdd4p is an Abbe number of the negative lens constituting the cemented lens in the fourth lens group.
14. An imaging apparatus comprising:
the imaging lens, as defined in claim 1.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A filter comprising:
an external light shielding sheet which includes a base unit and a plurality of pattern units that are formed on the base unit and that have a smaller refractive index than the base unit,
wherein each of the pattern units includes at least one curved edge.
2. The filter of claim 1, wherein the curved edge has a curvature radius of 10 \u03bcm to 3 mm.
3. The filter of claim 1, wherein the curved edge has a curvature radius of 100 \u03bcm to 800 \u03bcm.
4. The filter of claim 1, wherein each of the pattern units includes at least one outwardly extending, curved lower edge.
5. The filter of claim 1, wherein the refractive index of the pattern units is 0.3-1 times higher than the refractive index of the base unit.
6. The filter of claim 1, wherein a thickness of the external light shielding sheet is 1.01-2.25 times greater than a height of the pattern units.
7. The filter of claim 1, wherein a distance between a pair of adjacent pattern units is 1.1-5 times greater than a bottom width of the pattern units.
8. The filter of claim 1, wherein a height of the pattern units is 0.89 4.25 times greater than a distance between a pair of adjacent pattern units.
9. The filter of claim 1, wherein a distance between tops of a pair of adjacent pattern units is 1-3.25 times greater than a distance between bottoms of the pair of adjacent units.
10. The filter of claim 1, further comprising at least one of:
an anti-reflection (AR) layer which prevents reflection of external light;
a near infrared (NIR) shielding layer which shields NIR rays emitted from the PDP; and
an electromagnetic interference (EMI) shielding layer which shields EMI.
11. A filter comprising:
an external light shielding sheet which includes an external light shielding sheet which includes a base unit and a plurality of pattern units that are formed on the base unit and that have a smaller refractive index than the base unit,
wherein the pattern units have curved bottom surfaces.
12. The filter of claim 1, wherein the refractive index of the pattern units is 0.3-1 times higher than the refractive index of the base unit.
13. The filter of claim 1, wherein a thickness of the external light shielding sheet is 1.01-2.25 times greater than a height of the pattern units.
14. A plasma display device comprising:
a plasma display panel (PDP); and
a filter which is disposed at a front of the PDP,
wherein the filter includes an external light shielding sheet which includes a base unit and a plurality of pattern units that are formed on the base unit and that have a lower refractive index than the base unit, and each of the pattern units has at least one curved edge.
15. The plasma display device of claim 14, wherein the curved edge has a curvature radius of 10-3 mm.
16. The plasma display device of claim 14, wherein the refractive index of the pattern units is 0.3-1 times higher than the refractive index of the base unit.
17. The plasma display device of claim 14, wherein a thickness of the external light shielding sheet is 1.01-2.25 times greater than a height of the pattern units.
18. A plasma display device comprising:
a PDP; and
a filter which is disposed at a front of the PDP,
wherein the filter includes an external light shielding sheet which includes a base unit and a plurality of pattern units that are formed on the base unit and that have a lower refractive index than the base unit, and the pattern units have curved bottom surfaces.
19. The plasma display device of claim 18, wherein the refractive index of the pattern units is 0.3-1 times higher than the refractive index of the base unit.
20. The plasma display device of claim 18, wherein a thickness of the external light shielding sheet is 1.01-2.25 times greater than a height of the pattern units.