Zoom lens

专利摘要:
From the object side, to the zoom lens comprising a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a negative refractive power, on the object side. The first lens group may be linearly moved toward an object, and the second lens group may include a first lens having a negative refractive power and a second lens bonded to the first lens to have a positive refractive power. The third lens group moves non-linearly to the object side, and the fourth lens group moves linearly to the object side, thereby suppressing the inward coma aberration in the telephoto end where the variation of the off-axis aberration is large, thereby providing excellent image quality. In addition, a zoom lens having a high ambient light ratio is provided.
公开号:KR19980059098A
申请号:KR1019960078434
申请日:1996-12-30
公开日:1998-10-07
发明作者:박천호
申请人:이대원；삼성항공산업 주식회사；
IPC主号:

专利说明:

Zoom lens
TECHNICAL FIELD This invention relates to a zoom lens. More specifically, it is related with the telephoto zoom lens for single-lens reflexes which correct | amends the fluctuation | variation of inward coma aberration in a telephoto end.
A zoom lens comprising a first lens group having a positive refractive power from a conventional object side, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a negative refractive power, The zoom lens was shifted by moving the first lens group and the fourth lens group together to the object side during shifting, and correcting image positions with the third lens group.
However, in the conventional zoom lens having the above-described configuration having four groups of lenses, since the exit angle of the light beam incident at an arbitrary angle is changed by the movement of the fourth lens group, the telephoto end has a large variation in the off-axis aberration. There was a problem that large inward coma aberration occurs.
Accordingly, an object of the present invention is to solve the conventional problem, and to correct the inward coma aberration in a telephoto end having a large correction of the off-axis aberration.
1 is a block diagram of a zoom lens according to an embodiment of the present invention,
2 (a) to 2 (c) are spherical aberration / astigmatism / distortion aberration at the wide-angle end of the zoom lens according to the first embodiment of the present invention,
3A to 3C are spherical aberration / astigmatism / distortion aberration at the intermediate end of the zoom lens according to the first embodiment of the present invention,
4A to 4C are spherical aberration / astigmatism / distortion aberration in the telephoto end of the zoom lens according to the first embodiment of the present invention,
5A to 5C are spherical aberration / astigmatism / distortion aberration at the wide-angle end of the zoom lens according to the second embodiment of the present invention,
6A to 6C are spherical aberration / astigmatism / distortion aberration at the intermediate end of the zoom lens according to the second embodiment of the present invention,
7A to 7C are spherical aberration / astigmatism / distortion aberration at the telephoto end of the zoom lens according to the second embodiment of the present invention.
According to an aspect of the present invention, there is provided a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth having negative refractive power from an object side. A zoom lens composed of a lens group, wherein the first lens group linearly moves toward an object side, the second lens including a first lens having negative refractive power and a second lens bonded to the first lens and having a positive refractive power The group is fixed with respect to the image plane, the third lens group moves non-linearly to the object side, and the fourth lens group moves linearly to the object side.
Then, the following equation is satisfied.

In the above equation, Is the focal length of the wide-angle end,
Is the total focal length of groups 3 and 4,
Is the focal length of the second group,
Is the focal length of the first group.
By the above-described configuration, a person having ordinary skill in the art to which the present invention pertains will be described in detail with reference to the accompanying drawings.
1 is a block diagram of a zoom lens according to an embodiment of the present invention,
2 (a) to 2 (c) are spherical aberration / astigmatism / distortion aberration at the wide-angle end of the zoom lens according to the embodiment of the present invention,
3A to 3C are spherical aberration / astigmatism / distortion aberration at the intermediate end of the zoom lens according to the embodiment of the present invention,
4A to 4C are spherical aberration / astigmatism / distortion aberration in the telephoto end of the zoom lens according to the embodiment of the present invention,
5A to 5C are spherical aberration / astigmatism / distortion aberration at the wide-angle end of the zoom lens according to the second embodiment of the present invention,
6A to 6C are spherical aberration / astigmatism / distortion aberration at the intermediate end of the zoom lens according to the second embodiment of the present invention,
7A to 7C are spherical aberration / astigmatism / distortion aberration at the telephoto end of the zoom lens according to the second embodiment of the present invention.
As shown in the accompanying FIG. 1, the zoom lens according to the embodiment of the present invention,
A first lens group 1 composed of two lenses from the object side and having positive refractive power and linearly moving toward the object side;
A second lens group 2 composed of three lenses and having negative refractive power and fixed to an image surface;
A third lens group 3 composed of four lenses, having positive refractive power, and having a non-linear motion toward the object side;
It consists of three lenses, has a negative refractive power, and comprises the 4th lens group 4 linearly moving to an object side.
The second lens group 2 is composed of a first lens 21 having positive refractive power from an object side and a second lens 22 bonded to the first lens 21 and having negative refractive power. Correct inward coma aberration.
With reference to the accompanying Figures 1 to 7 will be described the operation of the zoom lens according to an embodiment of the present invention.
In the zoom lens of the present invention, the first lens group 1 is linearly moved toward the object side and the second lens group 2 is fixed with respect to the image surface in order to shift from the wide-angle end to the telephoto end.
In response to the movement of the first lens group 1, the third lens group 3 moves nonlinearly toward the object side, and the fourth lens group moves linearly to the object side in conjunction with the movement of the third lens group 3. .
The first lens group 1 is composed of two lenses and finally refracts incident light in the forward direction.
The light refracted by the first lens group 1 is incident on the second lens group 2 composed of three lenses and finally refracted in the negative direction.
The first lens 21 having the negative refractive power from the object side of the second lens group 2 and the second lens 22 having the positive refractive power suppress the generation of inward coma aberration caused by the off-axis aberration fluctuations. Do it well.
The third lens group 3 is composed of four lenses so that the light passing through the second lens group 2 is finally refracted in the positive direction, and the fourth lens group 4 is three lenses. The light refracted by the third lens group 3 is finally refracted in the negative direction.
The lens groups 1 to 4 satisfy Equations 1 and 2 above.
Equation (1) is for determining the appropriate range of the focal length of the third lens group 3 in an expression related to the miniaturization of the overall length of the zoom lens.
The focal length of the third lens group 3 and the fourth lens group of Equation 1 ) Is greater than the upper limit, the focal length of the third lens group 3 becomes long, so that the airspace point (the store and the shop corresponding to the third lens group 3) in the third lens group 3 is increased. The interval becomes larger, resulting in an enlargement of the overall length of the zoom lens, which is smaller than the lower limit, and the focal length of the third lens group 3 is shortened, making it difficult to correct the balance of all aberrations starting from spherical aberration. .
In the above formula (2), if the absolute focal length of the second lens group 2 is smaller than the lower limit, it is difficult to reduce the influence of the diverging force of the second lens group 2 while being compact, and if it is larger than the upper limit, The amount of ambient light is reduced, causing a problem that requires a large aperture.
The value of the first embodiment of the zoom lens of the present invention, which satisfies the above equation, is shown in Table 1. The aperture number of the camera used in the first embodiment is 4-5.8, and the focal length is 71.5 to 201.7.
In Table 1, r is the radius of curvature, d is the thickness of the lens and the distance between the lenses, nd is the refractive index, and v is the Abbe's number.
r (curvature radius)d (thickness and distance)nd (refractive index)v (abbe) One82.780001.50001.8051825.46 243.938005.28001.6584450.85 3-337.05300A 41422.876001.00001.6385455.45 519.632003.72001.8051825.46 647.092002.5800 7-47.367001.00001.7725049.62 8113.79500B 987.857003.27001.4874970.44 10-60.000000.1500 1147.370004.48001.5168064.20 12-47.544001.00001.8051825.46 13833.769000.1500 1438.803002.78001.4874970.44 15336.359001.500 160.00000C 170.0000012.4500 1871.420003.69001.6476933.84 19-33.154001.10001.6385455.45 20-126.313002.2900 21-24.186001.10001.7725049.62 22-141.40300
A, B, and C of Table 1 are distances between the lenses when shifting from the wide end to the telephoto end, and Bf is the post focal length.
A, B, C, and Bf values at the wide-angle end, the intermediate end, and the telephoto end according to the first embodiment are shown in Table 2 below.
Focal Length (f)71.5109.0201.7 A1.25120.39639.663 B20.67313.7581.282 C18.99318.23419.005 Bf37.51845.17556.874 31.1531.3731.15
The focal length of the first lens group 1 is 120.31, and the focal length of the second lens group 2 is -32.19.
Values of a second embodiment of the zoom lens of the present invention that satisfies the above equation are shown in Table 3 below.
r (curvature radius)d (thickness and distance)nd (refractive index)v (abbe) One81.878001.60001.8051825.46 243.442005.63001.6584450.85 3-337.23900A 4-321.811001.20001.6385455.45 519.952003.43001.8051825.46 653.670002.1100 7-52.988001.00001.7725049.62 897.11000B 971.995003.26001.5115567.67 10-71.995000.1500 1147.309004.50001.5168064.20 12-47.309001.00001.8360625.25 136110.308000.1500 1444.902002.60001.5168064.20 15509.906001.4300 160.00000C 170.0000012.4500 1866.812003.43001.6476933.84 19-37.447001.10001.6385455.45 20-160.955002.5000 21-24.353001.10001.7725049.62 22-134.81100
A, B, C, and Bf values at the wide-angle end, the intermediate end, and the telephoto end according to the second embodiment are shown in Table 4 below.
Focal Length (f)71.3108.8201.8 A1.59320.65739.794 B20.67313.7601.282 C18.99818.99819.006 Bf37.50245.17556.874 31.0631.3731.15
In the second embodiment, the focal length of the first lens group 1 is 119.28, and the focal length of the second lens group 2 is -32.19.
The present invention provides a zoom lens having excellent image quality and high ambient light ratio by suppressing coma aberration in the telephoto end.

权利要求:
Claims (1)
[1" claim-type="Currently amended] A zoom lens comprising, from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having negative refractive power, wherein the first lens The group is linearly moved toward the object side, and the second lens group including a first lens having negative refractive power and a second lens bonded to the first lens and having a positive refractive power is fixed with respect to an image surface, and the third lens The group moves nonlinearly to the object side, and the fourth lens group moves linearly to the object side, and the zoom lens satisfies the following equation.
[Equation 1]
[Equation 2]
In the above equation, Is the focal length of the wide-angle end,
Is the total focal length of groups 3 and 4,
Is the focal length of the second group,
Is the focal length of the first group.

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同族专利:

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GB2320767B|1999-04-14|

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US5903398A|1999-05-11|

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引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
1996-12-30|Application filed by 이대원, 삼성항공산업 주식회사

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1996-12-30|Priority to KR1019960078434A

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1998-10-07|Publication of KR19980059098A

优先权:

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申请号 | 申请日 | 专利标题

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KR1019960078434A|KR19980059098A|1996-12-30|1996-12-30|Zoom lens|