PHOTOGRAPHIC OBJECTIVE HAVING AT LEAST SIX LENSES

Abstract

The present invention relates to a photographic objective having at least six lenses and at most eight lenses, with the first lens viewed from the object side being manufactured from glass and having a positive refractive power, an Abbe number of greater than or equal to 55, and a deviation of the relative partial dispersion from the normal line P.sub.g,F between 0.008 and 0.035.

Claims

1. A photographic objective comprising at least six lenses and at most eight lenses, wherein the first lens viewed from the object side is manufactured from glass and has a positive refractive power, an Abbe number of more than or equal to 55 and a deviation of the relative partial dispersion from the normal line P.sub.g,F between 0.008 and 0.035.

2. The objective in accordance with claim 1, wherein the objective comprises at least seven lenses.

3. The objective in accordance with claim 1, wherein, beside the first lens manufactured from glass, at least a majority of the remaining lenses are manufactured from plastic.

4. The objective in accordance with claim 1, wherein at least two lenses have at least one respective aspherical surface.

5. The objective in accordance with claim 1, wherein the Abbe number of the first lens is greater than or equal to 65.

6. The objective in accordance with claim 1, wherein the Abbe number of the first lens is smaller than or equal to 85.

7. The objective in accordance with claim 1, wherein the second lens has an Abbe number between 13 and 33.

8. The objective in accordance with claim 1, wherein the overall length L and the total focal length f of the objective satisfy the condition L/f<1.25.

9. The objective in accordance with claim 1, wherein the quotient from the overall length L and the diameter of the image circle is smaller than or equal to 0.7.

10. The objective in accordance with claim 1, wherein the image angle is greater than or equal to 80.

11. The objective in accordance with claim 1, wherein the f-number is smaller than 1.5.

12. The objective in accordance with claim 1, wherein the objective comprises, in an order from an end at the object side to an end at the image side and subsequent to the first lens, at least one second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power, a fifth lens having a positive refractive power, a sixth lens having a positive or a negative refractive power, and a seventh lens having a negative refractive power.

13. The objective in accordance with claim 1, wherein at least the fourth lens is configured as a meniscus lens.

14. The objective in accordance with claim 1, wherein the focal length of the first lens and the focal length of the second lens satisfy the condition
f1<|f2|.

15. The objective in accordance with claim 1, wherein the focal length f2 of the second lens, the focal length f3 of the third lens, and/or the total focal length f of the objective satisfies/satisfy at least one of the conditions
|f2|>f3
1.5<|f2|/f<4.0
1.0<f3/f<3.0.

16. The objective in accordance with claim 1, wherein the focal length f1 of the first lens, the focal length f4 of the fourth lens, the focal length f5 of the fifth lens, the focal length f6 of the sixth lens, the focal length f7 of the seventh lens, and/or the total focal length f of the objective satisfy/satisfies at least one of the conditions
f1<|f4|
f1/f5
f1<|f6|
1.0<f1/f<2.0
5.0<f4/f<2.0
3.0<f6/f<7.0
2.0<f7/f<0.8

17. The objective in accordance with claim 1, wherein the common focal length f.sub.12 of the first lens and of the second lens and the total focal length f of the objective satisfy the condition
0.8<f.sub.12/f<2.5.

18. The objective in accordance with claim 1, wherein a main beam angle that corresponds to an angle of incidence onto a sensor arranged in the image plane relative to the normal amounts to a maximum of 37.0 over the total image field.

Description

[0040] The invention will be described in the following with reference to embodiments and to the drawings. There are shown:

[0041] FIG. 1 a lens section of an objective in accordance with a first embodiment of the invention;

[0042] FIG. 2 diagrams of the aberrations of the objective of FIG. 1;

[0043] FIG. 3 a diagram of the spherical aberration of the objective of FIG. 1;

[0044] FIG. 4 diagrams of further aberrations of the objective of FIG. 1;

[0045] FIG. 5 diagrams of the longitudinal chromatic aberration of the objective of FIG. 1;

[0046] FIG. 6 a lens section of an objective in accordance with a second embodiment of the invention;

[0047] FIG. 7 diagrams of the aberrations of the objective of FIG. 6;

[0048] FIG. 8 a diagram of the spherical aberration of the objective of FIG. 6;

[0049] FIG. 9 diagrams of further aberrations of the objective of FIG. 6;

[0050] FIG. 10 a diagram of the longitudinal chromatic aberration of the objective of FIG. 6;

[0051] FIG. 11 a lens section of an objective in accordance with a third embodiment of the invention;

[0052] FIG. 12 diagrams of the aberrations of the objective of FIG. 11;

[0053] FIG. 13 a diagram of the spherical aberration of the objective of FIG. 11;

[0054] FIG. 14 diagrams of further aberrations of the objective of FIG. 11; and

[0055] FIG. 15 a diagram of the longitudinal chromatic aberration of the objective of FIG. 11.

[0056] FIGS. 1, 6, and 11 show a respective photographic objective having seven refractive lenses L1 to L7 in accordance with three different embodiments. The lenses L1 to L7 are numbered in ascending order in a direction of light propagation of the optical path starting from the object side to the image side. Relative position indications such as in front of or behind relate to this order.

[0057] The objectives each comprise a first lens L1 having a positive refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, a fourth lens L4 having a negative refractive power, a fifth lens L5 having a positive refractive power, a sixth lens L6 whose refractive power is positive in the first and second embodiments and negative in the third embodiment, and a seventh lens L7 having a negative refractive power. The first lens L1 is surrounded by an aperture diaphragm A that is located approximately on the first surface of the lens L1. A planoparallel plate P is provided as a cover plate behind the seventh lens L7. The planoparallel plate P can be configured as a band-elimination filter for non-visible light (UV light and/or IR light) so that only visible light is transmitted. An image sensor can be arranged with its sensor plane S in the focal plane B.

[0058] The first lens L1 and the planoparallel plate are manufactured from glass; the second to seventh lenses L2 to L7 are produced from plastic. The glass used for the first lens L1 has a deviation of the relative partial dispersion P.sub.g,F from the normal line of +0.009 for the first and third embodiments and of +0.019 for the second application example.

[0059] Detailed design data and optical data for the lens elements of the objective are shown in the following tables. The data relate to the surfaces that designate respective air-to-glass or glass-to-glass transitions and are numbered in ascending order from the end at the object side to the end at the image side. The surface 0 thus designates the object plane 0 at an infinite distance, the surface 1 the effective surface of the aperture diaphragm A, surface 2 the surface at the object side of the first lens L1, surface 3 the surface at the image side of the first lens L1, and so on. The last surface 17 is the surface at the image side of the planoparallel plate P. The surfaces 2 to 15 have an aspherical curvature. The focal length f, the f-number f/#, the overall length L, the image height, and the half image angle are likewise shown in the respective tables.

[0060] The following asphere equation applies to a sag z of a respective lens surface in parallel with the optical axis at a point having a height h relative to the optical axis and perpendicular thereto:

[00002]$z\left(h\right)=\frac{h^2/r.Math.0}{1+\sqrt{1-\left(1+k\right).Math.{\left(h/r.Math.0\right)}^2}}+a.Math..Math.4.Math.h^4+a.Math..Math.6.Math.h^6+\mathrm{.Math.}+a.Math..Math.16.Math.h^{1.Math.6}$

where r0 is the vertex radius of curvature, k is the conical constant, and A4, A6, . . . , A16 are the aspherical coefficients.

[0061] In the following tables, the respective vertex radius of curvature r0 (in millimeters), the conical constant (KK) k, the thickness d or the distance from the next surface along the optical axis, the refractive index of the respective optical material, the Abbe number, and the focal length (in mm) are given for the respective embodiments and the asphere coefficients A4 to A16 are given for the surfaces 2 to 15.

[0062] The aberrations of the objectives in accordance with the three embodiments can be specified in the form of a wavefront error W(p, A) that is described by a sum of orthogonal Zernike standard polynomials P.sub.i(p, A) (also written as Pi) and of associated coefficients Z; (also written as Zr) in the form

[00003]$W\left(p,A\right)=\underset{i=1}{\overset{1.Math.0.Math.6}{.Math.}}.Math.Z_i.Math.P_i\left(p,A\right)$

where p is the normed radial distance or the normed pupil coordinate and A is their azimuthal angle. p can adopt values between 0 and 1. Wand Z.sub.i are given in coordinates of the wavelength.

[0063] Only the coefficients Z4, Z11, Z22, Z37, Z56, Z79, and Z106 are given in the respective tables for the respective rotationally symmetrical Zernike polynomials in the Zernike standard representation. The other Zernike coefficients are 0 since only the axial image point for an object at infinity is looked at. The associated rotationally symmetrical standard Zernike polynomials Pi are defined as follows:

P4=3.sup.1/2.Math.(2p.sup.21)

P11=5.sup.1/2.Math.(6p.sup.46p.sup.2+1)

P22=7.sup.1/2.Math.(20p.sup.630p.sup.4+12p.sup.21)

P37=9.sup.1/2.Math.(70p.sup.8140p.sup.6+90p.sup.420p.sup.2+1)

P56=11.sup.1/2.Math.(252p.sup.10630p.sup.8+560p.sup.6210p.sup.4+30p.sup.21)

P79=13.sup.1/2.Math.(924p.sup.122772p.sup.10+3150p.sup.81680p.sup.6420p.sup.442p.sup.2+1)

P106=15.sup.1/2.Math.(3432p.sup.1412012p.sup.12+16632p.sup.1011550p.sup.8+4200p.sup.6756p.sup.4+56p.sup.21)

TABLE-US-00001 First embodiment: Focal length f 4.65 mm f-number f/# 1.45 Overall length L 5.60 mm Image height 4.10 mm Half image angle 40.0 Refrac- Abbe Sur- Ele- Radius Thick- tive num- Focal face ment r0 KK k ness d index ber length 0 Object Plano 1 Aper- Plano 0.705 ture 2 Lens 1 1.872 0.27 0.954 1.5378 74.7 5.69 3 3.944 0.00 0.292 4 Lens 2 3.550 0.00 0.216 1.6707 19.2 17.38 5 2.661 0.00 0.098 6 Lens 3 4.153 0.04 0.425 1.5449 55.9 7.58 7 1878.147 0.00 0.396 8 Lens 4 13.281 0.00 0.402 1.6707 19.2 13.50 9 29.656 522.90 0.235 10 Lens 5 7.762 0.00 0.460 1.6613 20.4 16.36 11 4.644 1.86 0.072 12 Lens 6 2.304 0.00 0.548 1.5449 55.9 21.71 13 2.619 0.00 0.385 14 Lens 7 45.558 0.00 0.209 1.6150 25.9 5.54 15 3.719 0.00 0.169 16 Cover Plano 0.210 1.5168 64.2 lens 17 0.521 Surface a4 a6 a8 a10 2 1.327E03 1.407E02 1.513E02 1.011E02 3 1.331E02 2.220E04 7.955E03 9.670E03 4 1.270E01 3.874E02 2.893E02 2.785E02 5 1.383E01 7.376E02 1.355E01 1.348E01 6 2.025E02 6.622E02 1.808E01 1.647E01 7 1.047E02 6.526E03 1.553E02 5.700E02 8 1.045E01 7.732E03 3.767E02 1.053E02 9 4.468E02 8.883E02 1.095E01 7.834E02 10 1.622E01 1.765E01 1.039E01 5.462E02 11 5.854E02 9.342E03 4.248E02 2.557E02 12 1.432E01 3.649E02 3.703E02 2.475E02 13 4.999E02 2.554E02 1.504E02 3.541E03 14 1.119E01 6.644E02 1.892E02 2.932E03 15 1.485E01 6.409E02 1.652E02 2.509E03 Surface a12 a14 a16 2 3.299E03 4.528E04 0 3 4.459E03 7.283E04 0 4 1.230E02 2.440E03 1.838E04 5 5.826E02 9.204E03 7.971E05 6 7.464E02 1.462E02 5.364E04 7 4.248E02 1.408E02 1.881E03 8 3.480E02 3.302E02 9.177E03 9 3.731E02 9.475E03 9.436E04 10 2.099E02 4.803E03 4.749E04 11 7.770E03 1.222E03 7.837E05 12 8.065E03 1.249E03 7.469E05 13 3.754E04 1.351E05 3.710E07 14 2.542E04 1.164E05 2.198E07 15 2.224E04 1.064E05 2.123E07 Zernike coefficients Z4 0.02259354 Z11 0.04163554 Z22 0.03177698 Z37 0.01030995 Z56 0.00177185 Z79 0.00181112 Z106 0.00405671

TABLE-US-00002 Second embodiment Focal length f 4.75 mm f-number f/# 1.45 Overall length L 5.60 mm Image height 4.12 mm Half image angle 40.0 Refrac- Abbe Sur- Ele- Radius Thick- tive num- Focal face ment r0 KK k ness d index ber length 0 Object Plano 1 Aper- Plano 0.640 ture 2 Lens 1 2.037 0.21 0.751 1.5927 67.0 6.45 3 3.759 3.79 0.223 4 Lens 2 2.657 0.03 0.190 1.6707 19.2 12.71 5 1.971 0.00 0.095 6 Lens 3 2.718 1.96 0.604 1.5449 55.9 6.34 7 11.572 0.00 0.474 8 Lens 4 30.167 0.00 0.379 1.6707 19.2 26.37 9 11.157 850.44 0.265 10 Lens 5 8.427 0.00 0.403 1.6613 20.4 309.4 11 8.257 223.25 0.076 12 Lens 6 2.336 0.00 0.531 1.5449 55.9 17.63 13 2.835 0.11 0.437 14 Lens 7 41.612 0.00 0.367 1.6150 25.9 6.03 15 3.415 0.68 0.169 16 Cover Plano 0.00 0.210 1.5168 64.2 lens 17 0.00 0.425 Surface a4 a6 a8 a10 2 3.79E04 4.31E03 7.24E03 3.16E03 3 1.59E02 4.31E03 1.08E02 4.10E03 4 1.04E01 8.20E02 9.84E02 6.40E02 5 1.50E01 1.37E01 1.58E01 9.96E02 6 4.64E02 9.97E02 1.43E01 1.22E01 7 8.31E03 5.13E04 2.82E02 5.52E02 8 5.77E02 7.72E02 1.18E01 9.09E02 9 1.50E02 1.26E01 1.05E01 5.33E02 10 1.24E01 1.39E01 9.35E02 6.19E02 11 2.83E02 4.63E02 4.91E02 2.57E02 12 1.72E01 6.56E02 5.31E02 2.87E02 13 8.13E02 7.96E04 2.34E03 1.86E04 14 1.73E01 7.93E02 1.94E02 2.84E03 15 1.64E01 6.41E02 1.56E02 2.36E03 Surface a12 a14 a16 2 3.78E04 3.69E04 8.90E05 3 1.53E05 1.80E04 0.00E+00 4 1.58E02 5.85E05 3.31E04 5 2.34E02 7.20E04 6.05E04 6 6.29E02 1.90E02 2.37E03 7 5.13E02 2.54E02 5.59E03 8 1.72E02 1.10E02 4.67E03 9 1.21E02 3.26E04 3.32E04 10 2.76E02 7.13E03 7.98E04 11 7.37E03 1.10E03 6.75E05 12 8.12E03 1.15E03 6.56E05 13 2.40E04 4.22E05 2.41E06 14 2.49E04 1.20E05 2.48E07 15 2.21E04 1.18E05 2.69E07 Zernike coefficients Z4 0.04517135 Z11 0.05512979 Z22 0.01687755 Z37 0.00821987 Z56 0.01754453 Z79 0.00946136 Z106 0.00708409

TABLE-US-00003 Third embodiment Focal length f 4.78 mm f-number f/# 1.45 Overall length L 5.60 mm Image height 4.13 mm Half image angle 40.0 Refrac- Abbe Sur- Ele- Radius Thick- tive num- Focal face ment r0 KK k ness d index ber length 0 Object Plano 1 Aper- Plano 0.640 ture 2 Lens 1 2.054 0.000 0.680 1.5927 67.0 5.50 3 4.854 0.003 0.069 4 Lens 2 2.457 0.000 0.197 1.6707 19.2 9.68 5 1.729 0.000 0.144 6 Lens 3 3.504 0.002 0.645 1.5449 55.9 6.37 7 41.031 4.722 0.242 8 Lens 4 21.367 0.334 0.565 1.6355 23.97 949.5 9 20.544 0.534 0.340 10 Lens 5 4.671 6.947 0.433 1.5449 55.9 5.98 11 1.986 0.605 0.031 12 Lens 6 7.947 16.210 0.553 1.6355 23.97 19.57 13 22.322 37.502 0.497 14 Lens 7 4.300 4.698 0.407 1.5094 56.47 3.86 15 3.764 0.072 0.050 16 Cover Plano 0.000 0.210 1.5168 64.2 lens 17 0.000 0.540 Surface a4 a6 a8 a10 2 6.80E04 1.05E03 4.78E03 5.43E03 3 1.83E02 3.68E03 2.67E03 1.06E03 4 6.77E02 8.27E03 2.50E02 2.14E02 5 9.56E02 2.11E02 8.88E03 8.11E04 6 1.87E02 2.82E02 4.53E02 1.64E02 7 1.83E02 6.74E02 1.35E01 1.33E01 8 7.36E02 2.22E02 6.15E02 4.26E02 9 8.03E02 8.67E02 1.60E01 1.27E01 10 8.72E02 2.11E01 2.72E01 1.83E01 11 1.07E01 6.24E02 4.40E02 8.31E02 12 1.59E01 2.37E01 1.46E01 5.17E02 13 5.13E02 8.21E02 4.07E02 1.11E02 14 8.77E02 6.89E03 2.33E02 8.03E03 15 1.12E01 2.80E02 2.46E03 4.95E04 Surface a12 a14 a16 2 2.57E03 4.60E04 0.00E+00 3 5.51E04 1.97E05 0.00E+00 4 6.96E03 8.41E04 0.00E+00 5 5.07E03 1.16E03 0.00E+00 6 1.32E03 4.27E04 0.00E+00 7 6.83E02 1.30E02 0.00E+00 8 1.57E02 1.58E03 1.13E04 9 5.15E02 7.07E03 6.26E04 10 6.34E02 8.37E03 3.31E05 11 4.29E02 9.29E03 7.31E04 12 1.06E02 1.39E03 1.17E04 13 1.69E03 1.32E04 3.98E06 14 1.24E03 9.33E05 2.78E06 15 1.50E04 1.47E05 5.19E07 Zernike coefficients Z4 0.001123 Z11 0.060063 Z22 0.067759 Z37 0.026434 Z56 0.018399 Z79 0.004181 Z106 0.013461

[0064] Different aberrations will be specified for the three embodiments in the following.

[0065] The transverse aberrations ex, ey (in m) for the normed pupil coordinates x and y directions for the axial image point are reproduced in FIG. 2 for the first embodiment, in FIG. 7 for the second embodiment, and in FIG. 12 for the third embodiment. The end of scale values of the transverse aberrations ex, ey each amount to +/50 m.

[0066] The spherical longitudinal aberration (in mm) in dependence on the normed pupil coordinate is reproduced in FIG. 3 for the first embodiment, in FIG. 8 for the second embodiment, and in FIG. 13 for the third embodiment, in each case for the colors red (R), blue (B), and green (G).

[0067] The astigmatism (in mm) in dependence on the half image angle (called +Y, in degrees) and the distortion (in percent) in dependence on the half image angle (in degrees) are reproduced in FIG. 4 for the first embodiment, in FIG. 9 for the second embodiment, and in FIG. 14 for the third embodiment.

[0068] The longitudinal chromatic aberration of a focal length displacement (in m) in dependence on the wavelength (in m) is reproduced in FIG. 5 for the first embodiment, in FIG. 10 for the second embodiment, and in FIG. 15 for the third embodiment.

REFERENCE NUMERAL LIST

[0069] A aperture diaphragm [0070] B image plane [0071] O object plane [0072] P planoparallel plate [0073] S sensor plane [0074] L1-L7 first to seventh lenses