DE1622990A1 - Optical lens with continuously changeable focal length - Google Patents

Description

P 16 22 990.6-51 February 5, 1970

The Rank Organization ReLi-Gu-5428

Optical lens with continuously variable focal length

The invention relates to an optical lens for photographic or other purposes which has members which can be moved relative to one another and in which the equivalent focal length can be continuously changed over a predetermined area with a constant image plane. Such optical lenses are referred to as "rubber lenses ^11. The change in focal length is carried out by a control element. The adjustment to changes in the object distance is achieved by an additional movement of an objective element through a further control element for focusing. The invention relates in particular to an optical objective with variable focal length, which is made up of thin lenses and which is corrected for spherical and chromatic aberrations, coma, astigmatism, field curvature and distortion.

Various types of rubber lenses are already known. Most of them have an anterior and posterior lens array on. The rear arrangement is stationary. Movable links for changing the focal length are located in the front arrangement. Such an objective generally contains four or five elements. Two or three behind one

TO 98 dd / 0271

1622930

Links lying in front of the link can be moved to change the focal length. The front link is fixed when the focal length is changed. These last-mentioned links form the front arrangement. Focusing is generally done from the front member of the front assembly.

The term "front" or "rear" refers to that Side of the lens that is closer to or further away of the longer conjugated or conjugation lies »This is a common indication.

It is very much in the calculation and construction of rubber lenses difficult to combine several advantageous properties, namely a wide-angled field of view or field of view with a minimum equivalent focal length, furthermore a large focal length range with an acceptable relative movement of the limbs and a front limb that can be focused to a very short object distance. The greatest difficulty in building and calculating a lens with such wide-ranging requirements exists therein, using thin lenses, an optimal solution to find that allows a slight aberration correction in a practical lens.

To overcome these difficulties, a lens has already been made proposed with variable focal length, which consists of four members, namely a convergent front member, the is fully or partially movable for focusing, two divergent links arranged behind the front link, which can be moved to change the focal length, and a fixed rear link. In the case of a collecting or convergent fore limb, mu3 however, one can make a relatively large forward movement of this limb in order to focus on a nearby object can. Furthermore, the angular field behind the front link is greater

BAD ORIQIiMAL

109882/0271

-3- 1622890

is than that in the object space, one must make the diameter of the fore limb larger in order to obtain what is necessary for focusing To compensate for movement. In the practical case, one would use a wide-angled field of view with the minimum focal length require a complicated and expensive front link which is very difficult to correct for aberrations could. Such a fore limb that could be focused on a very close object would be in terms of Size, weight and effort impractical.

The invention is therefore based on the object of creating a lens of variable focal length that has the stated widths Requirements in terms of wide-angle, focusing and the range of change for the focal length are met and the described difficulties and disadvantages eliminated.

A lens of variable focal length with a fixed one posterior arrangement of one or more divergent limbs and with an anterior arrangement of four limbs, of of which the first or front link is divergent and stationary with respect to the change in focal length and of which the second, third and fourth term is convergent, divergent or convergent, the second and fourth term .gemeinam nach push forward and the third link hung down at the same time moves, is characterized according to the invention in that. . ·

(a) Ijjps> f ₂ >

^f 4

(c) f > ₂

BAD ORSQINAL

109882 / 02-7 1

(d) ^ / r> g ₄ > g ₂

2 (f «+ f /,) - x 2 (fp + f /,) - x

(f) ImZTr: _{>g> s} ^

where Fm is the maximum value of the equivalent focal length of the entire lens, N the relative aperture or f-number of the lens, fp> £ ■ * and f, the equivalent focal lengths of the second, third and fourth elements, g ₂ , gz and g ₄ the ratio between the maximum and minimum magnification of the second, third and fourth link, R the ratio of the maximum to the minimum focal length of the entire lens and χ the mean value of the sum of the distances from the rear node of the second link to the front node of the third link and from the rear node of the third link to the front node of the fourth link. . ·

These six relationships given above give the limit values for an optimal one formed from thin lenses Structure, for which you can select practically possible parameters for correcting the lens. By being starting from any thin lens of the above-described arrangement of five members and then starting from Doing a thorough optimization on this arbitrary starting point, one obtains the six given above Relationships.

BATH ORIGINAL 103852/0271

_ ₅ _. 1522990

With the relation (a) one achieves a sufficient compromise between the total length of the lens, the overall diameter, particularly at the front end, and the relative openings or apertures of the various Lens elements. So that the absolute total length of the lens is as small as possible, fp should be larger as f / be. This leads to relationship (b), which in combination with the relationship (a) ensures that the absolute value of the entire diameter is on a practical Value is held.

Relationships (a) and (b) relate to the second link of the lens. This link is very critical, particularly with regard to the overall diameter of the objective. However, this element is also the most important element for stabilizing the aberrations in the focal length range. The optimization shows that the magnification ratio gp of the second member should be limited in accordance with the relationship (c) in order to encounter the least difficulty in an arrangement with thick lenses for performing the aberration correction. On the other hand, the dimensions of the fourth element, in particular its relative opening or aperture, not particularly critical to the structure of the entire lens, so that g, the enlargement ratio, can make this member is larger than the magnification ratio g ₂ "and up to a Limit of - \ [R. Provided that the enlargement ratios of the second and fourth links are appropriately selected, this relationship enables precisely parallel movement of the second and fourth links, so that the movement can be carried out with a simple mechanical structure.

BATH

According to the given relationships, the equivalent focal length f, of the third term must be dependent on can be chosen from the focal lengths of the second and fourth link, on the one hand an impractical design with negative air clearances and to avoid on the other hand the total length of the lens as small as possible to keep. This gives the relationship (e).

Since gg · g ^ · g / j_ = R, it follows the limit values for the magnification ratios g ~ and g ^ the relation . (f) to a large range of change of the equivalent Ensure the focal length of the entire lens.

The six relationships mentioned determine the general position of the nodes in a structure with thick lenses, whereby one arrives _{at the relationship f ^> f 2.} In this way, with a rubber lens of the type described, it is possible to focus down to extremely short object distances. In the practical case, f * <1.5 fo is preferred.

From the above explanations you can see how to using the six basic relationships given, arrives at a practical arrangement with thin lenses, which meets the broad requirements mentioned at the beginning with continuously variable focal length.

In developing a practical lens with thin lenses various other types are created Relationships that focus primarily on the

bilization of the aberrations by changing the focal length Refer to the system that is formed by the front arrangement of the first to fourth members, and the Control the stabilized aberrations are used so that these in the rear arrangement, which consists of one or more fixed links can be corrected. · "

In this context, the exact structure of the front link is not important. The foreleg should be constructed in this way be that it ensures an aberration stabilization during its movement necessary for focusing, what is not part of the present invention.

However, in order to obtain sufficient optical performance in the second link and to correct chromatic To support aberrations, the second link preferably includes a composite convergent link portion. Furthermore, an increase in the optical performance of this composite part is desirable, and although preferably by a simple convergent part at the rear of the assembled part. This also makes it easier to move the rear node of the second link backwards, making it taking into account the movement required by the relative Limitations is possible, the air gap between the second and third link as small as possible to keep. The structure of the composite link part is important for aberration stabilization. It contains preferably a divergent element and a conjugated element made of materials with Abbechen.V-numbers, the down at least by 20 in terms of chromatic

109882/02 7 1.

1622350

Distinguish aberrations. The refractive indices of the materials of these elements preferably differ by a value between 0.1 and 0.25 in order to help stabilize the spherical aberration. A contribution to spherical aberration stabilization and distortion correction is achieved in that the inner contact surface between the elements is convex towards the front. The radius of curvature is between 0.8 fp and 1.6 f ₂ · The front surface of the second link plays no role in stabilizing and controlling spherical aberration and coma and preferably has a large radius between 5 f ₂ and oo . The rear surface of the composite part, on the other hand, is important for spherical aberration and distortion and is preferably concave towards the front with a radius between 2 fρ and 5 f ₂ The rear surface of the second member is in its entirety for the stabilization and control of all monochromatic aberrations important and preferably has a relatively large radius between 2 fp and oo.

The third link preferably also contains a composite link part which, however, is divergent, to help control the chromatic aberration. To reinforce works with this compound Part at least one simple divergent limb part that lies in front of him and serves to avoid strongly curved surfaces. As in

109882/02 7 1

1522930

_ 9 -

the composite part in the second member and for similar reasons the composite part in the third link preferably a convergent element and a divergent element, their materials differ by at least an Abbe V number of 25 and their refractive indices by less than 0.3 are different. The inner contact surface is convex to the front with a radius of less than f ,. To control astigmatism, coma, and distortion, the simple divergent element (or one of these elements) in front of the assembled part, preferably convex-concave, whereby it is convex to the front and the radius of its rear surface is smaller than the distance to the barrier (in the case of the front Surface of the posterior phalanx) at a position of minimum focal length Fo.

In order to further assist in the control and stabilization of the chromatic aberrations, the fourth element preferably contains at least one composite convergent element which cooperates with at least one other convergent element for amplification. For finer control of chromatic aberrations, the fourth member preferably includes a divergent element made from a material whose Abbe V number is at least 15 less than the mean of the Abbe V numbers of the materials of all the elements in that member. The stability of the coma

and the spherical aberration is aided by that one for the radii of the consecutive first three of the Surfaces of the fourth member exposed to air, if rr »o: i counts from the beginning, chooses numerically smaller v / grounding values that exceed 0.7f /.

Under the above-mentioned inner contact surface of a composite Part of the limb should not only have a cemented touch surface, but also a "broken" touch This is understood to mean an area where the contact surfaces have radii that differ from one another by a small amount and where the effective radius of the inner contact surface is given by the arithmetic mean of itself slightly differing radii is formed.

A parameter that is used to stabilize and control a The type of aberration that makes a considerable contribution at one area location can be different at another area location Way, for example, help control another type of aberration. The punctures given above of the various parameters of the second, third and fourth part Link are therefore the basic functions of these arrangements. In addition to this, however, these measures can still be carried out with 'other.-r. Agents work together to perform other functions.

Embodiments of the invention made up of thin lenses and having a variable focal length are to be described with reference to figures will.

Pig. FIG. 1 is a schematic representation of one of FIG Invention constructed lens, the. movable members are in the position with the minimum equivalent focal length Po.

BATH ORIGINAL

105882/02 71.

FiS. Fig. 2 is a similar illustration, but is true the movable members in the position of maximum equivalent Focal length Pm are.

Contains the objective shown schematically in these figures a front arrangement with limbs that are under the control a control element for setting the. Focal length are movable, with the focal length of the entire lens at constant position of the image plane P is changeable, and a rear arrangement, in front of an optical barrier or a Iris diaphragm D is arranged. '. . '

The front arrangement has a divergent front limb 1 which is fixed when changing the focal length. Follow that a convergent second link 2, a divergent third link 3 "and a convergent fourth link 4. The second, third and fourth link are for changing the focal length at the same time movable in their axial direction. While To increase the equivalent focal length of the entire lens, members 2 and 4 move nsch forward by equal distances move, link 3 moves at the same time rear .. The movement of the third link 3 depends on the shift of the second and fourth link 2 and 4 made by equal distances, in such a way Way that the position of the image plane is retained.

The rear arrangement contains an iMstezeg & aä & a ^ rear member 5, which is fixed and has such an equivalent focal length to give the entire lens the desired absolute :! To give focal length change range without changing the range and without influencing the structure of the rubber lens series formed by the first four links.

• BATH

1 09882/02 7: 1 v, "'■, -; * * c _; > r

Other absolute focal length ranges can be obtained by that in a known way the rear link is replaced by another.

The foreleg 1, which - with a view to the change in the focal length - is fixed, is independent of the shifts to adjust the focal length for the purpose of focusing in conventional 'Movable way.

The displacements to be made of the movable members 2, 3 and 4 require "careful consideration. There are very ■ many possible combinations for the focal lengths, magnifications and displacements of these links that make up the relationships meet according to the invention. The following are two methods of optimizing one made up of thin lenses Arrangement according to the invention described.

In the first method, the focal lengths fp and f. the links 2 and 4 are chosen arbitrarily and each link is considered in its two complementary positions, in which the magnifications mp or v /. m, and 1 / mp and 1 / ra ,. be. The displacements of these two terms 2 and 4 ~ between these positions is equal to the distance between their conjugate distances, and their conjugate points v / ground be the same in both positions.

The focal lengths fp and fi could be made the same, but this does not provide the optimal solution. On the other hand, equal movements of the limbs 2 and 4 'are preferred (although this is not necessary), and for this reason unequal values for ra ₂ .and m, are preferred, which are then given unequal values for fp and .f. work together so that equal movements can be performed.

§ÄD ORIGINAL 109882/02 7 1

1622930

With regard to atf the f-number and equivalent focal length (Po or Pm) for the lens, for example, the focal length f _{2 of} the outer element should be assumed to be 2 and the focal length f of the fourth element 4 should be assumed to be 1 1/9, then at nu = 1/2 and m "= 2 the conjugate distances for the second term 2 f ₂ (ui ₂ i-1) and fp > ^m 2 ^f ' , so 5 uiid

The conjugate distances for the fourth term are f _A (ta, + 1] (m / H) - · * "* · ■

- ^ - j so 3 1/3 and 1 2/3, and the shift

m
. for the fourth term is 1 2/3.

The displacement or movement of the third link, and the choice of f-, are then given by the position of the rear conjugate point of the second link 2 and the front conjugate point of the fourth link "4. The distance between the links 2 and 4 bä. Thin lenses must be chosen in such a way that the distance between these conjugate points is 4 £ · ζ at a point in the relative displacement range and is nowhere less than 4f *.

The distance between these conjugate points is equal to the distance T over which the third element 3 'must be shifted, that is to say the object / image dimension. The two conjugate distances are given by the following expression:

T - V T ^d - 4Tf * *

10988270271

1§2299Q

Since the anterior conjugate point of the second link 2 is fixed, If one chooses a larger fourth for f ^ than for f ~, so that the focal point of the front link 1 with the orteffecten " anterior conjugate point of the second limb 2 coincides, whereby the condition is met that the anterior limb at the change in the focal length is fixed.

This way you can adjust the front arrangement like this
build that an extraordinarily large reduction range is available for the focal length and thereby minimal • diameter for the links 1 to 4 and minimal distances between the links are achieved, but these are still
are large enough for the necessary shifts in an arrangement with thick lenses.

The focal length f, - of the rear link 5 is finally in; With regard to the absolute focal length of the area. The rear member 5 can also be chosen so that there is a particular relative opening or aperture (for the entire lens) for a particular purpose. In this package, the required focal lengths can be achieved by using the lens accordingly

In the second method of building an arrangement with thin lenses, one starts from a point in the region of the relative displacement at which the second, third and fourth members work simultaneously with the unit magnification. From the choice of the focal lengths for these members, their distances for this point of the area result directly. It is then possible from this point outwards to the two extreme values of the range Po and

BAD ORiGfNAL

109882/027 1

Work towards Ii ¹ Ui and solve the quadratic equation with the segment 'T of the third term 3 point by point until the total area required has been confirmed. For terms 1 and 5, one proceeds in the same manner as in the first method, while the conditions for minimum distances between the terms are obtained by adjusting or correcting the values chosen for fp, f ~ and f.

A numerical example for an arrangement of thin lenses according to the invention, which is obtained by the method described above, will be based on the following explanations described.

In this example: f ₁ = -133; f ₂ = 96.14; £? = '-46.03; f = 76.94. The rear member 5 is divergent, but when using thin lenses it has a very large focal length, which is assumed to be co. Should these Weri "a zoom ratio of 30 to 310, a relative aperture or opening for the entire? Lens of f .. and an image diameters are achieved of 40 The ratio gp between the maximum und'.minimalen magnification of the second member.. 2 is therefore 1.63 The corresponding ratios g and g for the third and fourth elements 3 and 4 are 3.12 and 2.03 · The ratio R of the maximum to the minimum equivalent focal length of the entire lens is 10.35. The sum χ of the distance between the rear node of the second link 2 and the front node of the third link 3 and the distance between the rear node of the third link 3 and the front node of the fourth link 4 is 149.98.

BAD 109882/02 71 _{; :} ,

-16-. '

The displacements of the elements 2, 3 and 4 'are given by the following final values, where S ^,' ² IS ₁ -, "and S _n ^ di.e are corresponding distances between the successive elements of the objective, and from front to back:

distance 93 Po Pin code , 09 ^S T1 24 , 55 - 46 , 92 ^S T2 125 , 87 130 , 06 S. , 11 19th

^s ! .4 '9.0 61 ", 46 The barrier D coincides with the rear link 5.

The values for the distances S ^., To S ™ / between the two End positions Po and Pm can be as described above Procedure calculated v / earth.

By simple arithmetic one can check that the numerical example given above is based on thin lenses represents constructed optimal arrangement according to the relationships given by the invention. It follows from this that you can build a lens from thin lenses, that the required wide-angled field of view, the large range of change for the equivalent focal length with relatively simple mechanical shifts and the possibility of still very close objects correctly to focus.

BATH ORIGINAL

109882/0271

1822990

Two lenses made according to the invention are described with reference to the drawings »

Figures 3 and 4 show two completely corrected rubber lenses) in both cases the movable members are in the position of the smallest equivalent focal length Wo . '■

The numerical values for these two embodiments are shown in the following! Tables' R, E _2, etc. denote the radii of curvature of each surface, if you start counting from the front, wobei.das positive sign means that the surface is convex forward , while the negative sign 'means that the surface is concave towards the front. D-, Dousw. bseichnen the'axiale thickness of the individual elements. S-, So'etc. denote the axial air gaps between the parts of the objective. "The tables also contain the mean refractive indices η for the d-line of the spectrum, dB Fig see T-number for 'the materials from which the various elements' of the objective are made, and the clear diameters of the different surfaces.

Since each rubber lens contains three movable members in its front arrangement, there are four variable air gaps. These are listed in the second part of each table. The values for the changeable air gaps are given under the assumption that the lens is focused to infinity (since the focusing movement of the foreground affects the first of these changeable air gaps) and that the lens is set to a series of focal length settings which are determined by the equivalent focal length j? of the entire object vis, if this is from the

BATH 109 * ^{82/1) 271 r} iC- *

Kinimal value Ί? Ο after the maximum word Pm is adjusted. For the sake of completeness, the lower part of each table also shows the changeable distances for thin lenses, these being labeled A, B, G and D.

The third part of each table finally contains the Equation defining an axial section through a non-parar surface, which in the fixed Rear section of the lens is provided.

^ßAD

Eeiopiel 1 Table 1

radius

Lens thickness or air gap

He equation index η Ab "see lights for the d-line V-number diameter

R ₁ 11 +23.333 D ₁ o, 333 1.64050 60.10 10,400 I. I. R ₂ I c. +12,000 S ₁ 0.720 .9,667 C. ^R 13 1 0.333 1.6405.0 60.10 - * +33.333 ^S 2 3.467 9.613 0 9 8. V +17.133 9.180 -20.667 D ₇ . 0.867 1.80518 25.43 8,000 KTKJ
^^ O ^R 6 - 8.333 0.333 1.58904 ' 53.01 7.933 NJ Ό 0.820 -R ₇ 7.307 R ₈ -9,200 D ₅ 0.333 1.46450 65.77 7.233 ö R ₉ - -72.788 ^S 4 changeable 7.113 ^R io D ₆ 0.267 1.80518 25.43 R. 7.333 CD +8.667 D ₇ 1.733 1.69680 56.18 7.700 δ ο, -14.667 Sc 0.00667 7,800 2 • % \ +46.133 ^8th 0.900 1.69680 56.18 8,000

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, .10,000 _{Og 0 | 735}

■ ί 32.681 _s ^ _{veränäerlDar}

t 5.180

D ₁₀ . 0.133

^f -> ¹⁰⁰ S ₃ 0.320

"19 ^f10 ' ⁴¹³ D ₁₁ 0.133

"21
^J -22

■ ρ

"23

26th

ί- 3.933

- 19.160
+2.493
f 5.026

f23,733
- 7.193
+ 3.90.7

Sq 0.400 JD ₁₂ 0.100 D ₁ ^ 0.500

ver f.na er "bar 0.400

0.00667 0.800

Brcc-hun ^ sindex η
for as d-line Abbe's c he
V number Lights
, Diameter 8,000 1,640.50 60.10 7,800 7.733 1.72000 "^; 50.41 '3.367 3.167 . 1, 72000. . · 50.41 3.167 3,100 1.56873. 63.08 . 3.133 1.80518 25.43 * 3.233 .. 3.233 1.68900 49.48 3.267 3,300 1.69680 ' 56.18 X 3.300

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109882/0271

From s tän el ο boi thick lentils

¥ Λ S ₇ 7, ^ö 10 S ₁₂ 1,000 3.0896 0.0706 5, 6575 0.2755 1.525 2.7078 1.7290 3, 9992 0.6573 3.075 1.9574 4, Q622 3, 6658 1.4075 3,588 . 1.7736 4.5290 1992 1.5915

5.952 1.1290 5.9956 1.7324 2.2359-

8.070 0.7182. 6.8624 0.8658 2.6469

10,000 0.4182 7.4780 0, '2500 2.9467

A. Distance with thin ones lenses D. J ¹ 7.2386 • B- C. 0.9004 1,000 6.8568 1.3416 8.2056 1.2820 1.525 6.1066 3.0000 • 6.5474 2.0324 3.075 . 5.9226 5.3333 4.2140 2.2164 3,588 - 5.2782 5.8000 3.7474 2.8608 5,952 4.8672 7.2666 2.2806 3.2718 8.070 8.1334 1.4140

10,000 4.5674 8.7490 0.7982 3.5718

Equation for non-spherical surface

χ = -13.811- ^ 190.743721.-f A ₄ y ⁴ + A ₆ y ⁶ ₊

where A ₂ = 0.3989925.x 10 ~ ²
A ₄ = -0.42625912 χ 10 " ⁵

A ₆ = -ο, β '^ 32097 x 10 " ⁵ A ₈ = -0.14074694 χ 10" ² A ₁₀ = 0.11075916 χ 10 ~ ²

109 8 8 2/0271

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10988 ^ / 0271 _8A D

• Radius

Lens thickness or Aerial fruit

Refractive index η for the d-line

From ^-1 D it before
V-Zs hl

Lights! Diameter

ο ι
to

R ₁ '. -'6,4OO R ₁₅ + 5,000 R ₁₆ -,. 21,705

R ₁₇ 4 2.590 + 1.550-

ru

H ₁₉ I 5.207 R _9n +1.967 H ₂₁

-9,580

R ₂₂ . + 1.247 + 2.513

R ₂₄ +11.867 H ₂₅ - 3.597 H ^ +1.953

5 ₆ 0.00333 D ₉ o, 367

5 ₇ changeable D ₁₀ 0.0667

Sg 0.160

D ₁₁ 0.0667 'S _g 0.200

D ₁₂ 0ρ30. ^ ₁₃ 0.250

5 ₁₀ changeable D ₁₄ 0.200,

5 ₁₁ 0.00333 D ₁ , 0.400

1.64050 1.72000 1.720Ό0

1.56873 1.80518

1.68900 1.69680

60.10

50.41

4,000 3,900 3,867

1.685 1.583

50.41 1,583 1,550 63.08. 1.567 25.43 1.617 1.617 49.48 1.635 1,650 1,650

radius

LxnsendickG or Luftafcstand

Formation index η for the d-line

See
V number

-2,333
f 8.860

0.0667

changeable

-3.897
(non-spherical

17 '

40.8569
+1.3675

0.1571

is °>¹⁹⁸;

■ - I. + ° , 7292 S ₁₄ 0.5166 O ? ^R 33 -1 , 7778
, 3356 D _1g 0.0659 9 882/0 H ₃₅ , 6835 S ₁₅ 0.1886
D ₂₀ 0.1397 ro ^R 36

1.80518

1.69689

1.50137

1.69680

1.50137 '

25.43

56.18

56.4-1

56.18

56.4-1

Li c Ub 1-Durchaosser

1.650 1.567

0.9913 0.9893 '0.9330

0.7760 0.732?

0.7423 0.741 ^; r

CQ CD O

A "b stands" for diel: on lenses

5 ι , 000 1.4847 ■ S ₇ A. B. 3 , 8287 C. ^S 12 lenses 1 , 525 1.2938 ' 0.0.244- 3.6193 0.6708 2 , 9996. , 1028 0.1377 • · D 1 , 075 0.9186 0.8536 3.4284 1.5000 1 , 8329 , 27J7 0.3286 . 0.4502 3 , 588 0.8267 ' 2.0202 3.0533 2.6667 1 , 5996 , 1070 0.7037 0.6410 3 , 952 0.5044 2.2536 • 2.9613 2.9000 O , 8662 , 8737 0.7957 1.0162 5 , 070 0.2990 2.9869 2.6391 3.6333 0 , 4329 , 1403 1.1179 1.1082 8th , 000 0.1490 3.4203 2.4336 4.0667 0 , 1250 , 7070 1.3234 1.4304 10 3.7281 2.2837. 4.3745 thin , 3991 1.4733 1.6359 Distances at Equation for 1.7859 j? , 000 4th the non-spherical surface 1 , 525 3 1 , 075 2 3 , 588 1 3 , 952 1 5 , 070 0 8th , 000 O 10

yi-5,186609 y

x = -3.897+ yi-5.186609-y

where A ₂ «-0.13871131 x 10" ² A ₄ = - 0.27256508 χ 10 " ² A ₆ = - 0.27346482

A ₆ β -0.22625624 • A ₁₀ = 0.58752824 '

BAD ORIGINAL 109882/0271

In both exemplary embodiments, the maximum value is the equivalent focal length Pm. of the lens in the change area about ten times greater than the minimum value Po. In the first example, the back focal length is from the back

Surface of the lens to the image plane 0.7530 Po and in the second Embodiment 2.8638 Po. -.

In the first embodiment, the lens sweeps over a half-angled field of view that extends from 30 ° at Po changed to 3 ° at Pm. In the second embodiment the corresponding values are also 30 ° and 3 °. the relative aperture or aperture of the entire lens is f / 2.0 in the first embodiment and f / 4.0 in the second EXAMPLE OF EXECUTION.

The iris diaphragm is fixed, and just before the front surface RNQ ^ ^he rear assembly arranged with regard to both embodiments.

109882/0271

In the first embodiment, the equivalent focal length fj of the front member (the surfaces R1 to R9) is -8.7622 Po, the equivalent focal length f «of the second member (surfaces R ₁₀ to R ₁₆ ) is -6.9394.Po, the equivalent focal length f * of the third link (surfaces R ₁ P to R23) -3.1328 Po, - while the equivalent focal length f, of the fourth link (surfaces R ₂₄ to R ₂₈ ) is 4.1000 Fo. The positive and negative signs indicate a convergent or. divergent limb.

The following numerical values apply to the second exemplary embodiment: f., = -4.3811 Po, f ₂ = 3.4697 Po, f ~ «-1.5664 Po, f ₄ * 2.0500- Po.

The mean value χ of the sum of the distances from the rear node point of the second link to the front node point of the third link and from the rear node point of the third link to the front node point of the fourth link is 9.5474 in the first embodiment and 4.7737 in the second embodiment

The magnification _{ratios g 2} , g * and g ^ of the second, third and fourth "elements are 1.4180, 3.0000 and 2.3507 in the first embodiment and also 1.4180, 3.0000 and 2.3507 in the second embodiment .

The magnification ratios, together with the values for f ₂ and f, result in the same movement or displacement of the first and fourth elements when the focal length of the objective is changed in both exemplary embodiments. It is therefore possible to use a relatively simple conventional control device since the support bodies for the second and fourth links are firmly connected to one another

109882/0271

sw

In the first embodiment, the equivalent focal length f _{1 of} the front link (surfaces R1 to R9) is -8.7622 Po, the equivalent focal length fp of the second link (surfaces R ₁₀ to R-jg) is 6.9394 Po, the equivalent focal length f , of the third member (surfaces R ₁₂ to R ₂ *) -3.1328 I ¹ O, while the equivalent focal length f, of the fourth member (surfaces Rp, ^ ^{is R} ? 8 ^ 4 »" is ¹⁰⁰ O ^ ° · The positive or negative signs characterize a convergent or divergent term.

The following numerical values apply to the second exemplary embodiment: f ^ -4.3811 Po, f ₂ = 3.4697 Po, f, = -1.5664 Po, f ₄ = 2.0500 Po.

The mean χ of the sum of the distances from the rear Junction of the second link to the front junction of the third link and from the rear junction of the third link to the front node of the fourth link is 9.5474 in the first embodiment and 4.7737 in the second embodiment.

The magnification ratios q ₂ j S3 ^and ^ € 4 ^ of the second, third and fourth term are 1.4180, 3.0000 and 2.3507 in the first embodiment and also 1.4180, 3.0000 and 2 in the second embodiment, 3507

The magnification ratios together with the values for fp and f result in the same movement or displacement of the first and fourth members when the focal length of the objective is changed in both exemplary embodiments. It is therefore possible to use a relatively simple conventional control device since the support bodies for the second and fourth links are firmly connected to one another

10 9882/0271 bathroom original

can be. In contrast to a known rubber lens of five links which performs similar relative movements, an important characteristic of the present invention is that these same movements or displacements of the second and fourth links are achieved without f ₂ and f being the same have to.

Both embodiments satisfy the six claimed Relationships so that a rubber lens which satisfies wide requirements can be obtained. Furthermore, the two correspond Execution ^ shape the preferred relationships to the control and stabilizing the aberrations in the second, third and fourth terms. The 'movable limbs are therefore arranged in both examples in such a way that a high level of stabilization of the various aberrations can be achieved through the entire change range of the focal length achieved, so that with a fore limb, which has a good stabilization of the aberrations over its entire independent Shift range for focusing provides the stabilized aberrations in the front arrangement (the first four links) by a corresponding structure of the fixed rear assembly (the rear Link) can be balanced.

With regard to the front link, it is of the greatest importance for the invention that this link should be divergent, with a focal length f ₁ which is numerically greater than f '«· With such a structure of the front link with the described second, third and fourth links it is possible to focus up to / w on an object distance / ** H3Fse33Ebg ^] Sfc = B ^^

being the terms given in the tables

have handy dimensions. The exact structure of the ^ - the q / eica * (*** o / ovioe / Ä *

109882/0271 'SAD

su result. Without a differently designed rear section, the change range for the absolute focal length and rear focal length of the second exemplary embodiment would be dimensioned in accordance with the first exemplary embodiment. In the case of a rubber lens with the aforementioned broad requirements and the associated high quality, as indicated in the exemplary embodiments, the rear link must also be correspondingly complicated. However, in order to achieve good aberration correction with a short axial length of the rear element, the rear element has a non-spherical surface, which is given by the front surface R ₂ Q in each of the two exemplary embodiments.

The embodiments mentioned are used in particular for a television camera, the dimensions are selected such _t, need to satisfy the various Karoerasystemen. The lenses according to the invention can, however, also be used in film cameras _{p it} very likely that the rear section will have to be replaced by another. Without deviating from the structure implemented with thin lenses, it is possible to modify the embodiments described above, for example in order to improve the control and stabilization of certain aberrations, for which the parameters of the front arrangement would have to be changed. In this context it should be pointed out that the different types of surface radii changed by up to 0.5f. can be, where f = f.,. f «, £ ■ * or f., depending on which link or links contain the surface or surfaces to be changed. The various lens thicknesses and axial distances can be changed accordingly, up to 0.05f, where

109882/0271

materials with different refractive indices are used and apart from V-numbers can choose exclusively from negative values and impossible constructions.

^BATH

109882/02 7 1

Claims (10)

Claims 1. Lens changeable focal length with a fixed one posterior arrangement and with an anterior arrangement of four limbs, the first or anterior limb of which is divergent and is fixedly arranged with regard to the change in focal length and of which the second, third and fourth members are convergent, is divergent or convergent, with the second and fourth members pushing forward simultaneously to enlarge the focal length and the third link moves rearward at the same time, characterized in that (f> \ 1 »8 fm v- 0.6 fm (b) f ₂ > f ₄ r _{> g2} > i (d) AJr > g ₄ > s ₂ 2 (f ₂ + f ₄ ) -x 2 (f ₂₊ f ₄ ) -x (e) yfy where Fm is the maximum value of the equivalent focal length of the entire lens, N is the relative aperture or f-number of the lens, fp, fz and f _{4 are} the equivalent focal lengths of the second, third and fourth elements, respectively, ggtg ^ and g ₄ the ratios between the maximum and minimum magnification of the second, third and fourth link, R the ratio of the maximum to the minimum focal length of the entire lens and χ the mean value of the sum of the distances from the rear node of the second link to the front node of the third link and from the rear The node of the third link to the front node of the fourth link is. ■ BAD OHlQIf ^ L f098 82/0 2 71 (Art. 7 £ l para. 2 No. J sentence 3 of the Äntounflüges, v. & Ä- 2. Lens according to claim 1, characterized in that the change ranges for the magnification of the second and third member _{differ from one another by such a value depending on the difference between f 2} and f ^ that the second and fourth member (2 and 4 ) while changing the focal length in the same way. 3. Lens according to claim 1 or 2, characterized in that 1.5 f ₂ >^> ^ ₂ where f ^ is the equivalent focal length of the front link (1). 4. Lens according to one of the preceding claims, characterized in that the second member (2) has a composite convergent link part and at least one simple convergent link part behind the composite link part which contains a divergent element and a convergent element whose inner contact surface is forward is convex and has a radius (R ₁₁ ')' which is between 0.8 f ₂ and 1.6 f ₂ , 'and that the elements are made of materials whose Abbe V numbers differ from one another by at least 20 and whose Refractive indices between 0.1 and 0.25 are different from one another. 5. Lens according to claim 4, characterized in that the radius (R ₁₀ ) of the front surface of the second member (2) is between 5 f ₂ and oo, while the rear radius (R ₁ 5) of this member between 2 and f ₂ O ₀ and that the rear surface of the composite link portion is concave towards the front and has a radius (R ₁₂ ) which is between 2 fρ and 5 f ₂ . 6. Objective according to one or more of claims 1 to 5 »characterized in that the third link (3) contains a composite divergent link part and at least a simple divergent link part in front of the composite link part, which has a divergent element and a convergent element whose inner contact surface is convex to the front and has a radius (Ro ₂ ) of less than f, and that these elements are made of materials whose Abbe V numbers differ by at least 25 and whose refractive index 109882/0271, _. BATH ORIGINAL indices differ between 0 and 0.3. 7. Lens according to claim 6, characterized in that the simple divergent link part (or at least one of these link parts) in front of the composite link part of the third link (3) is concavo-convex, it being convex to the front and the radius (FLg or Rp ₀ ) its rear surface is less than the axial distance between this surface and the plane through the lens barrier (on the front surface of the rear member (5)) at the position of the minimum equivalent focal length Fo. 8. Lens according to one or more of claims 1 to 7 » characterized in that the fourth link (4) comprises at least two convergent link parts of at least one of which is a composite limb, and that one of the link parts of the fourth link has a divergent element made of a material whose Abbe's V number is at least 15 less than the mean the Abbe's V-numbers of the materials of all convergent Elements that form part of the fourth link. 9. Lens according to claim 8, characterized in that the first three surfaces of the fourth member (4) lying in the air counted from the front radii (R ₂ ^, R ₂ Kf ^R 26 ^ ^mi * decreasing values have the greater than 0, 7 are f4. 10. Lens according to one of claims 1 to 9 »characterized in that f ^ is equal to or greater than about 0.6 f ₂ . BAD ORlQINAa. 109882/02 7 1 «36 Blank page