DE2334056A1 - WIDE ANGLE LENS WITH LARGE OPENING AND AN ASPHAERIC SURFACE - Google Patents

Description

Priority: July 4, 197J., No. 47-66359, Japan

The invention relates to a wide-angle lens with large Aperture in which aspherical surfaces are used that meet certain conditions.

A wide-angle lens is mostly used when photographing in Spaces used where there are spatial limitations that allow photographing an object from a long distance impede. Since the overall luminosity within a room is insufficient in many cases, one would like a lens the brightness of which is as great as possible. A wide angle lens built into a single lens reflex camera must still have a long back focus. This is why retrofocus lenses are used. A conventional one Retrofocus wide angle lens with a field angle of over 80 however has a maximum brightness due to the

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Aperture of F = 2.8, which meets the requirements for the Brightness is not sufficiently taken into account.

The object on which the invention is based is therefore to provide a retrofocus super wide-angle lens with a large Opening or aperture with an angular field of 84 and a brightness (corresponding to an aperture) of F = 1.4 or above, with a focal length that reaches 1.4 times the focal length, but with a small size but sufficient image aberration correction to accomplish.

This object is achieved in the objective according to the invention in that a plane from a lens group behind the diaphragm of a retrofocus objective is formed as an aspherical surface. A paraxial or near-axis radius of curvature at an apex of the aspherical surface is expressed by Ri. The X-axis is assumed to be in the direction of the progressing light on the optical axis, while the Y-axis runs in a direction perpendicular to it. The equation for the aspherical surface is then:

Y ² 4 6 8 ¹ "

X =, + BY * + CY ^D + DY ° +

γι -

The refractive index of the medium in front of and behind the aspherical surface is expressed by Ni and Ni ^1, respectively. The objective according to the invention must then meet the following conditions:

B (Ni ¹ - Ni) < O C (Ni ^f - Ni) <O

In order to effect the correction of the aberrations satisfactorily, the following conditions must also be satisfied.

30 9 8 8 3/1187

The entire objective or the entire lens system consists of three groups. Group I is a lens group with overall negative refractive power. It consists of a lens with a concave meniscus, a convex lens and a lens with concave meniscus arranged in this order. Group II is a lens group with overall positive Refractive power. It consists of a biconvex lens and a concave lens arranged in that order are. It can also consist of a concave lens and a biconvex lens in the following order. Group III is a lens group with an overall positive refractive power. It consists of a lens with a concave meniscus, which comprises a minus lens and a plus lens attached to one another, and of two convex lenses, those in said Order are arranged. At least one lens of group I or group II is formed by placing it next to one another, A screen is provided between group II and group III. Finally, the following conditions must be met:

(1) 2.3 f <L <3.5 f

(2) 1.2 f <1 ^ 1 < 3.5 f, fj < 0

(3) 1.2 f <JF ₁₁ <3, ο f (40 l, of <f _IIX <2.5 f

where L is the total length of the lens system

f the aperture of the entire system

f _{T is} the focal length of group I.

f _{T is} the focal length of group II

f _{TTT is} the group III focal length.

Furthermore, a plane of group III is designed as an aspherical surface. When a paraxial radius of curvature at the apex the aspherical surface is expressed by Ri, the X-axis along the direction of passage of light on the optical

309883/1187

2 Ό ^ ¹ ■ '' ^ * "Γ"

Axis and the Y-axis is perpendicular to this direction, the equation applies to the aspherical surface:

2
X = + BY ⁴ + CY ⁶ + DY ⁸ + EY ¹⁰ +,

Ri + Ri ^ j 1 -

i ^ j

If the refractive index of the medium in front of and behind the non-spherical surface is expressed by Ni and Ni *, respectively, must the following conditions are met:

(5) <IB (Ni * - Ni) I <^, B (Ni '- Ni) <0

f ^J f ^J

( ₆ ) ° ζ j C (Ni - Ni) (<- lf, C (Ni '- Ni) <0

The retrofocus lens with a minus lens group that is im is arranged in the front part, and a plus lens group, which is arranged in the rear part, has an asymmetrical lens arrangement, which makes the correction of image errors difficult, especially the correction of minus or negative distortion Distortion and the negative coma error or the negative asymmetry error generated by the minus lens group, which is arranged in the front part. If the errors are corrected so that they become small, other image errors, in particular, the spherical aberration and the longitudinal scattering or the longitudinal overexposure are worsened.

Since it is also necessary to make the retro ratio larger to ensure the required back focal length, since the field angle becomes wide, d. H. the focal length of a lens is short, the asymmetrical characteristics of the Lens arrangement great. Since there is still a need to increase the refractive power of each lens, that of aberrations produced by each lens, so that it is difficult to

3 09883/1187

OBiGiNAL INSPECTED

to achieve a lens with a large aperture. While it it is necessary to reduce the refractive power of each lens in order to meet the above requirement in a lens system, which consists only of spherical surfaces, the total length of the lenses becomes large, which leads to the fact that the The diameter of the front lens becomes very large and thus it becomes difficult to obtain a practical size to verify.

The cause of the above condition (l), i.e. H. the Condition 2.3f <L <3.5 f over the entire length of the invention Lens, is to keep the diameter of the front lens in the range of a practically feasible size and to make the whole system space-saving. The aspherical surface is used to solve the aberration problems generated for the above reasons. If the upper limit of this condition is exceeded, increases the diameter of the front lens to a size that is not practical. When a value is reached, which is below the lower limit, good image aberration correction cannot be carried out even if aspherical Area as described below is used.

According to the invention, it is further required that the conditions (2), (3) 1 (^) are satisfied and the condition of using an aspherical surface is followed. The arrangement of the refractive power of each lens group must be determined. If the upper limit of condition (2), namely 1.2 f <Jf ₁ (^ 3.5 f, is exceeded, it becomes difficult to keep the overall length of the lens in the range of a practical size, while if the value is lower is as the lower limit, the aberrations generated by the group I increase, so that the possibility of obtaining a lens having a large aperture is lost, and when the refractive power of the group II exceeds the upper limit of condition (3) , namely 1.2 f <fj _I <3i ° f, the

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The requirement regarding the refractive power of group III is extremely high and the aberration correction is difficult. If the value is lower than the lower limit, the negati \ ^r e takes spherical aberration, which is generated in the group II, too, so that it is difficult to obtain a lens with a large opening. The condition (^) ₁ namely l, of <fy-jj <2.5 f, consists in the fact that group III is related to group I and

Group II has a comparatively strong refractive power so that a long back focus can be achieved. When the top If the limit of this condition is exceeded, a sufficient back focus cannot be obtained. Will the lower If the limit is below the limit, the negative spherical aberration generated in the group III increases, so that a Large aperture lens is difficult to achieve.

According to the invention, such an image defect correction as required for an objective with a large aperture is to be effected in that an aspherical surface is used. Although a greater effect can be achieved if aspherical surfaces are used in many surfaces, since the freedom or possibility for an aberration correction increases, one would like to use a small number of aspherical surfaces inexpensively in this case, since the manufacture of aspherical surfaces is difficult and is costly. According to the invention, taking into account the above statements, a sufficient effect is to be ensured, although the use of aspherical surfaces is limited to a single such surface. When an aspherical surface is used, the negative spherical aberration, negative distortion, negative asymmetry error and side flare that remain as a result must be corrected effectively at the same time. However, if the aspherical surface;, n of Group I or Group II is used , the correction of the distortion and the asymmetry error (coma) leads to an increase in the spherical aberration and the off-axis stray light

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or the non-axial overexposure, so that this arrangement is not suitable for a lens with a large aperture. Used if, on the other hand, the aspherical surface in group III is behind the diaphragm, it is possible to use the aforementioned correct residual aberrations with sufficient compensation. This is especially possible if the aspherical surface is used in 'an image-side convex plane of the lenses lying on top of one another. The compensation the correction of the chromatic aberration in the longitudinal direction and in the lateral direction becomes satisfactory. If the shape the aspherical surface is provided so that it meets the following conditions in connection with the fourth and sixth coefficient of aspherical surfaces according to the conditions (5) »(6) is sufficient, one obtains in best results in this case:

(5) <| b (Ni '- Ni) I <! 2. β (Ni '- Ni) <O

f- £ ^{5 J}

( ₆ ) ο ^ £ ° 1 _< je (Ni '- Ni) J <-i | , C (Ni '- Ni) <O ■

The fourth and sixth coefficients influence the BiJ.derror and are related to each other. When the fourth coefficient is lower than the lower limit of condition (5), can correct the negative spherical aberration in dec * center of the light flux, the negative asymmetry error in the intermediate image and negative distortion cannot be performed satisfactorily. When the upper limit is exceeded, the asymmetry error of the intermediate image and the astigmatism are overcorrected, which is not desirable is. When the sixth coefficient becomes lower than the lower limit of condition (6), the correction of the negative spherical aberration in the peripheral area of the light flux, the negative asymmetry error, the external image and the lateral blooming cannot be carried out satisfactorily. If the upper limit is exceeded, will

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overcorrects the spherical aberration in the peripheral area of the light flux, which is undesirable.

If the above conditions are satisfied, it is possible to obtain a retrofocus wide-angle lens which has an angular field of 84, a brightness of F = 1.4 or more, a back focus of 1.4 f or more, and a small size, however, the various artifacts are corrected satisfactorily. Furthermore, the following points must be taken into account in order to ensure very good image defect correction. First, the radius of curvature R _T on the image side of a convex lens in group I must satisfy the following condition:

- o, 4 f < _Έ - <0

I-convex

In this way, the distortion is intended to a certain extent at this point which can occur in group I. When the upper limit of this condition is exceeded becomes, the correction effect of the distortion becomes small, while the lateral light flux in the circumference at this plane Excessive deviation is made when the value is lower than the under limit. Also, the diameter of the front Lens big, which is not wanted. On the other hand, the radius of curvature on the image side of the convex lens must be at the Group II meet the following condition:

< ¹ ^ -Τ "' ^R II-convex <°

I \ < ¹ ^ Τ ' ^R II-convex II-convex

This condition is used to a certain extent at this point the negative distortion and the negative Correct asymmetry errors (coma). When the lower size If this condition is not met, the correction effect of the distortion and the asymmetry error is lost,

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while the circumferential light beam on the axis in this plane converges excessively, resulting in the high-grade spherical aberration is worsened, which is not advantageous for obtaining a lens with a large aperture is. Thirdly, besides these conditions, the mean value of the refractive index of the convex lens in group III be greater than 1.65. This is to correct the spherical aberrations which deteriorate in Group III can, and that the Petzval sum is improved, which can be bad with this arrangement.

The invention is explained in more detail with the aid of the accompanying drawings and the following exemplary embodiments.

Fig. 1 shows schematically the objective according to the example

FIG. 2 shows the aberrations of the lens of FIG. 1.

Fig. 3 schematically shows the lens of Example

FIG. K shows the aberrations of the lens of FIG. 3.

Fig. 5 shows the objective according to Example III.

Fig. 6 shows the aberrations of the lens of Fig. 5.

7 shows the objective according to Example IV.

FIG. 8 shows the aberrations of the lens from FIG. 7.

The letters used in the following examples and in the drawings with the assignment of current indices have the following meaning:

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- Io -

R is the radius of curvature of each refractive plane, with the asterisk being the paraxial radius of curvature at the apex the aspherical surface.

D is the on-axis lens power or the air gap between the lenses.

N is the index of refraction of the glass that makes up the lens.

V is the Abbe number of the glass in each lens.

FIGS. 2, 4, 6 and 8 show the ^v -UfJ ⁺ .and of the image aberration correction for each of the four exemplary embodiments. It can be seen that the angular field is 84 °, the brightness or aperture reaches F = 1.4 or F = 1.2 and the state of the aberration correction is satisfactory, while the focal length is 1.4 f or more.

Example I.

f β 24 _f 5 F y. ω s ± 42 °

R ₁ · 50 _? 193

H _x * If 5S913 V ₁ > 61 _? 1

^D l - ¹ ? 500 R ₂ a 22 _T 569 D ₂ s 11 .000 D ₃ u A ₁ 000 ^R 4 * D, 000

H ₂ «1.53913 V ₂

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D ₅ . 3,000 152.276 D ₆ «1,500 R ₇ . 1Ö.2S3 D _7-10.437 R ₈ β 2Sj795 D ₈ β 7 _r 000 R ₉ β -39.264 D ₉ s 0.200 ho s -117.070 D ₁₀ . 1,500 ^R ll «35,370
D _n e 10.631 ^R 12 s -15.854 D ₁₂ β 1,000 ^R 13 β 99.094
n, " * / Tm ^R 14 13 ^ f ^^
«-33J4Ö7 * D _u «0.15b ^R 15 ε -133.553 D ₁₅ β 5,000 ^R 16 «-25 _r 53O D _{16 s} 0.150 R ₁₇ ■ -79.919 D ₁₇ ■ 6,000 R-irt s -27.816

1.80518 V ₃ »25 _f 4

1.55913 V ₄ , 61.1

s 1.71300 V. «54.0

- 1.33921 V ₆ β 41 _r l

l _{# /} 8051S V _{7 s}

1.77250 V _{8 β} 49.6

1.77250 V _{9 8} 49 ^ 6

- 1.77250 V ₁₀

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Coefficient of the aspherical surface: B "0j20647 x 10" * · C β 0.3634.5 x ΙΟ * " ⁷ D κ -0 _T S0225 x ΙΟ" ¹⁰ E «0.52622 χ ΙΟ" ¹³

33 _f 572

Back focus s 36 ^ 500

Y X 0 0 1.225 0.02237 2,450 0.00899 3,675 V ■ <V J - t "" I Λ, 900 O, 34SO4 6.125 0.53406 7.350 O _? 751l5 9jÖ00 1.24937 11.025 1.51179 12,250 1.76322 13.4.75 2.00625 14 700 2.21315

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Aberration coefficient for example I 2334056

KO. I II III PV

1 0.0271 0.0256 0.0241 O ₁ ISlO 0.1932

2 -0.9128 0.3235 -0.1147 -0.4024 0.1833

3 0.0431 0j0629 0.0913 0.0212 0.1651 Λ -0.0005 0.0030 -0.0201 0.0336 -0.4572 5 '0 * 1931 0.1018 0 ^ 0537 0.2451 0.1575 6 0.0000 -0 _T 0009 0 ^ 0166 -0.0121 -0.0833

7 -3.5273. O _? U83 -O ₇ OO62 -0-4966

8 2 ₇ 7ό35 0 _T 6205 0 ^ 1393 0.35U 0.1103

9 3.0653 -1.6420 0.8795 0 ^ 2597 -0.6103

10 -1 ^ 0516 0.7844 -0.5852 -0 ^ 771 0.4940

11 -0.0702 -0.0691 -0.0630 -0.2568 -0.3196

12 -3.1371 0.6069 -0.1174 -0.639? 0.1561

13 -0.0853 -0.0538 -0.0339 -0.0025 -0.0230 U -7.2137 -1.9049 -0.5991 0.31 ^ 9 -0.4731

15 0.0436 0.1123 0.2893 -0.0800 0.5395

16 2 ^ 7144 -0.1320 0.0064 0.4182 -0.0207

17 -0.3225 0.1651 -0.0845 -0.1336 0.1117 13 7.9992 0.8450 0 _f 0893 0.3839 0.0500 £ 0.5280 -0.0033 -0.0391 0.1202 0.1946

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- Ik -

fa 24.5 F 1.4 ω * ± 42 °

R ₁ . 51 _T 399 1,500 D ₁ . Rg ". 23 ^ 939 10 _f 50 R ₃ » D ₂ a
146 _f 244 4 ^ 000 H* D ₃ s
-123,350 2,000 R ₅ . 36,242

η.297

-37.872

β 102.60S

YY ₁ »1.53913 V _{1 Β} 61.1

_β 1.53913 V _{2 β} 6l _y l

D ₆ β 1,500 K ₄ β I ₇ 5? Ί913 V ^. ₆ 1 _? 1

R ₇ * 16,966 309883/1187

* - ³ ^ f ¹⁷⁶ *

₅ β «159.331

^ 16 ^κ -25 * · 535

- 15 -

D ₉ .0.200 233405.6

R ₁₀ «31.802

* 5 _Τ 5ΟΟ N ₆ . 1 ^ 71 300 V ₆ , 5Λ.0

R ₁₂ * -15 ^ 730

D ₁₂ U 1,000% S 1 ^ 80513 V ₇ a 25.4

49.6

ο 5,000 I ^ μ 1.77250 V _{9 m} 4.9.6

D ₁₇ β 5j5OO H ₁₀ α l _f 77 250 V _{10 m} J® _f (>

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Coefficient for the aspherical surface:

B κ 0 ^ 21699 x

C κ 0.35319 x 10 " ⁷ D ~« 0.92699 x 10 '23 e O.61S5O x IO "

-XO

Y X O 0 1.225 0 _f 02191 2.4.50 0.08714. 'Λ, ^ ΟΟ 0 ^ 34012 6.125 0.52132 7,350 TZ- 9, ^ 00 l ^ llXJ 11 _? ϋ25 1.40170 12,230
ι 1.70517 2.12630

s -6Ο.4.Ο6 β 50.558

«33 _T 911 focal length _{m 36,500}

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Aberration coefficient for example II: KO. I Π HI P

1 0.0253 0.0256 0.0260 0.1767 0.2058 2 • 0.7385 0.2073 -0.0532 -0.3786 O.I226 3 Oj0664 0 _T 0733 0.082I 0 ^ 0621 0.1603 4 · *
Oj0003 -0.0019 0.0118 0 _T 0736 -0.5221 5 0.1984 0.10U 0.0515 0.3015 0.1799 6th 0.0032 -0 _r 0118 0.0432 -0.0103 -0 _? 1199 7th -2.6343 -0 _? 0781 -0.0023 -0.5354 -0.0159 8th 0 _T 0112 -0.0253 0 _f 0574 -0.2407 o, as2 9 -1.6542 -0 _? 7077 -0.3027 -0.0839 -0.1675 10 4.9272 l _t l630 0.2745 0.3206 0, U05 IX O _t 5157 -0.4080 0.3228 0.2600 -0 _f 4611 12th -3.3491 0.5285 -OjO834 -O76947 0.1228 13th -0 _T 0608 -0.0442 -0.0321 -0.0019 -0.0247 U -7.7454 -2.4780 -0.8642 0.3124 -O.5664 15th 0 _T 0364 0.0994 0.2714 -0.0668 0.5584 16 3.2324
■ * 0 _f 0654 0j0013 0 _? 4173 0-0085 17th -0.6685 0jl833 -0 ^ 0503 -0.1751 0 _? 06l8 18th 8 _T 2953 l _f 3124 0.2076 O ₇ >? 35 0.0951 0.4611 0 _t 0049 -0.0436 0 _M 1255 0.1931

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Example III

R ₁ κ 58j377

D ₁ β l _f 500% ₃ 1.58913 V ₁ . 6l _? l

D _? β 10,000 R ₃ s 85 ^ 255

D ₃ - A _? 500 N ₂ · 1 _? 59913 Y ₂ "^ f ¹ \> -101.797 -

m 2 _f 000

R5 * 61.033

R _{6 B} 19 _?

D ₆ »δ _? 26 ^ 0

D ₇ . 3 ^ 000 N ₄ - 1 _? δ0518 V ₄ «25 _; 4 62 ^ 807 D ₈ ■ 7 _? 960 N ₅ S Ij53913 V ₅ «61 _; 1

0.200

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D ₁₀ β Ij500 N ₆ β 1 60562 V ^ m Of?

R ₁₁ s 36 ^ 039

D ₁₁ a 9 _? 669

β -U.630

D ₁₂ «1-000 R ₇ * 1.80518 Vy _s 25.4

^R 13 = 43 _; 066

D ₁₃ s 5.500 % al _f 77250 Vg «Λ9 ^ 6

s l _? 77250

u 0jl5D

R ₁₇ ο -2fiB _f 67S

D ₁₇ ε 6 ^ 000 N ₁₀ «lj77250 V ₁₀ · / ₊ 9 _f 6

-27j46?

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- 2ο -

Coefficient for the aspherical surface:

B e 0.18703 x 10 "" ⁷ * C · 0.33565 x 10 ~ ⁷ D «-0.46ύ76 χ ΙΟ" * ¹⁰ E «0.23254 x ΙΟ" ¹³

233Ä056

r. -

40 ^ 756

^f III s 31,380 focal length β 36,500

Y X O O 1 _T 225 Ο ₇ Ο21 ^ 3 2 ^ 450 0.0 ^ 59 3 ₇ 675 0.19336 4,900 0.34042 6.125 0.52305 7.3ίίΟ 0.73691 ß _? 575 0.97552 9, 100 1.23063 11.025 1.49223 12,250
f 1.74832 13.475 1 _; 93-97 14 _T 700 2 ^ 13633

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Aberration coefficient for example III: I. II III P. 2334056 KO. Oy0172 0.0230 0 _f 0303 0.1556 V 1 -1 ^ 0347 0.3300 -0.1053 -0.4036 0 _; 249l 2 0.1845 0.1039 0.0535 0.1065 0.1623 3 0.0037 -0.0146 0.0573 0.0392 0.0930 4th O _T O368 0.0444 0.0536 0.1437 -0.5740 5 -3.49 ^ 5 0.2049 «0.0120 -0.4634 0.24'3 6th . 0.4390 0.0554 0.4113 0.0279 7th -0.0032 -0.0033 -0.004 '. -0.0294 0.0588 8th 2.4180 «1.4033 0 _f ni44 0.2490 -0.0394 9 -0.6449 0.5868 -0.5333 -0.0521 -0 _? 6176 10 -0.0472 -0.0535 -0.0606 -0.2561 0.5331 U -3.2777 0.6837 -0.1426 -0.7444 -0.3537 12th -0.1917 -0.1000 -0 _f 0522 -0.0058 0.1S ₅ O 13th ~ 6 _f 2570 -1.6964 -0.6050 0.3112 -0.0303 14th 0.0320 0.0986 0.3041 -0.1240 -0.5159 15th 1.0969 -0.1535 0.0229 0.3902 0.5557 16 -0.0046 0.0Hl -0.0433 -0.0370 -0 _f 0597 17th 0.9152 0.1028 0.2472 IS 0.4633 O _f 0136 -0.0595 0.1354 0.0552 0.2159

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Example IV 233 ^ 56

Fl _? 2

% s 52,538

D _1S 1,500 N ₁ -I ₁ # 913 V ₁ . ₆ l _f l

R2 5 23.253

D ₂ β 11,500 Hj's 2i ^ ₇ 462

D ₃ - 4 ^ 000 H _{2 B} 1 58913 V ₂ - 61

R ₄ . -114.240 D ^ m 2 _f 000

^R 5 s 62.037

D ₅ s 3 ^ 000 N ₃ - 1.30513 V ₃ - 25

Rg «-663 ^ 006

D ₆ s 1.500 N ₄ - 1.53913 Y ^ s 61.1

R ₇ «22.020

D ₇ s 10.176% »30.003

Dg _s S, 500 N ₅ s 1 ^ 71 300 V _{5 β} ^ ₀

R ₉ s -44.125

0.200

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RlO s -205.146

D ₁₀ * 1 ^ 500 R ₂₁ s 36 _t 176

D ₁₁ m 10.857 R ₁₂ β -15 _T 97O

_s 1,000

K ₆ . 1 ₇ 6O342 V ₆ - 38.0

₁₃ s 61jS07

s -34 ₇ 966 *

D ₁₄ s 0 _? 150 «-UO ₇

16 ^s -

R ₁₇ β -172 ₇ 401

-30.041

6 _f OOO

0 _T l50

7j000 H ₇

Kg «l _y 77250 V ₈ - 49.6

1.77250 V _{9 β} 49.6

¹¹ IO " ¹ T ^77250? 1O =

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2k -

Coefficient for the aspherical surface

B β 0.17296 χ ΙΟ " ⁷ * C e 0.32603 χ 10 ~ ⁷ D - -0 ^, 55526 χ ΙΟ * ¹⁰ E η 0.16503 x 10" ¹³

hl s

Y X 0 O 1.225 0.02143 2,450 0.03531 3,675 0.19043 4 _t 90O 0.33463 6.125 0.51468 7 _f 350 0 ^ 72607 ß, 575 0 ^ 96236 9,800 1.21753 11.025 1.43119 12 _T 250 1 _? 74327 13.475 1 _T 99239 up 2j21674 15 ^ 925
16,905 2.52333

Back focus S 36,500

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Aberration coefficient for example IV:

KO. I II III

1 0.0236 0 ^ 0237 0.0238 0.1727 0.1972 2 -O _? 8475 O _f 3l57 -0.1176 -0.3906 0 _T 1893 3 0.0532 0.0666 0 _? O833 0.0350 0.1480 4 ' -0 ^ 0003 0 _? 0024 -0.0180 0.0795 -0 ^ 542 5 0.0360 0.0737 O _f O631 0.1762 0.2049 6th 0.0033 - -0.0102 0.0318 0.0023 -0.1074 7th -2 _? 2493 -0.0036 -o _t oooo -0.4125 -0.0007 8th 2.1557 0 _f 5041 0 _M 1179 0 _T 3393 0.1070 9 2.2U6 -1.3303 0 _r 7991 0 _T 2311 -0.61ß9 10 -0.6532 0.5328 -0 _; 5l99 -0.0449 0.5039 11 -O ₇ 0454 -0.0502 -0.0554 -0.2549 -0.3429 12th -2.8419 0.5720 -0.1151 -0.6843 0.1609 13th -0.1078 -0.0666 -0.0411 -0.0040 -0.0279 U -5.9332 «1.8074 -O _f 6365 0.3054 -0.5047 15th 0.0190 0 _r 0 & * 3 0.2450 -0.0966 O ₇ 5326 16 1.6126 -0.0934 O _f 0054 0.3732 -0.0219 17th -0.0597 0-0677 -0.0766 -0.0619 0 ^ 1570 la 7.1664 1.1082 0.1714 0.3554 0.0815 0.5955 0.0234 -O.O396 0.1215 0.2039

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Claims (5)

PATENT CLAIMS Vl »J Wide-angle lens with a large aperture, characterized in that aspherical surfaces are used which meet the following conditions: B (Ni ¹ - Ni) <O
C (Ni ¹ - Ni) <O wherein a plane of the lens group behind the diaphragm of the retrofocus lens is the aspherical surface and the aspherical surface satisfies the following equation: χ _s - + BY ⁴ + CY ⁶ + DY ⁸ + EY ¹⁰ + i (/ ι - Ri + Ri where Ri is the paraxial radius of curvature at the apex of the aspherical surface, the X-axis is defined along the direction of the advancing light beam on the optical axis and the Y-axis perpendicular to this direction and the refractive index of the medium in front of and behind the aspherical surface Ni or Ni is ¹ . 2. Lens according to claim 1, characterized in that the aspherical surfaces continue to the following conditions suffice: ο, οοΐ / f ³ <j B (Ni '- Ni) I <- o, ool / f ⁵ <: JC (Ni -Ni) J <- 309883/1187 3 · Objective according to claim 1 or 2, characterized characterized in that the entire lens system consists of three groups, group I being a lens group that has a negative overall power and is off consists of a lens with a concave menius, a convex lens and a lens with a concave menius, which are arranged in this order, the group II is a lens group, the overall one positive Has refractive power and consists of a biconvex lens and a concave lens or a concave lens and a biconvex "lens, which are arranged in this order, and group III is a lens group, which overall have a positive refractive power h.at and off a lens with a concave meniscus, which has a minus and a plus lens placed next to one another, and off consists of two convex lenses, and at least one lens of group I and group II is formed by placing one next to the other that a panel between group II and group III and that the lens meets the following conditions: (1) 2.3 f <L <3.5 f (2) 1,2 f ^ I f _x | < 3.5 f, fj- <O (3) 1.2 f < ΐ _ττ <3, ο fl, of < Τ _τϊ1 <2.5 f where L is the total length of the lens, f is the focal length of the entire lens, f _{T is} the focal length of group I, f _{TT is} the focal length of group II, f is the focal length of group III. 309883/1 187 4. Lens according to one of the preceding claims, characterized in that the aspherical surfaces meet the following conditions: - o f < I-koiivex -o, 3 ^ Il-convex <l.o I. where R _T. the radius of curvature on the image side I-convex ° the convex lens of group I and R _TT ., the ^{1 x} II ~ convex Is the radius of curvature on the image side of the convex lens of group II. 5. Lens according to one of the preceding claims, characterized in that the aspherical surface is the plane on the image side of the Group III compound meniscus lens. 309883/11 87 Blank page