DD149826A1 - RETROFOCUS WIDE-ANGLE LENS WITH IMAGE ERROR COMPENSATION - Google Patents

Abstract

The invention relates to a retrofocus wide-angle lens with aberration compensation with a relative opening of 1: 2.4 to 1: 2.8 and a field angle between 74 degrees and 94 degrees, which is used in single-lens reflex cameras. The inventive wide-angle lens contains 8 to 10 lenses, which has largely been dispensed with high refractive Kronglaeser. The control of the image error compensation takes place by means of the variation of the aperture space. The production of this wide-angle lens is characterized by low production costs. The object-side objective part contains a biconvex lens, two scattering and one collecting meniscus. Separated by the diaphragm space, the image-side objective part follows, consisting of a biconvex lens, a biconcave lens, a collecting meniscus and another biconvex lens.

Description

9 5 49 - "-

Title of the invention:

Retrofocus, - Wide-angle lens with aberration compensation

Field of application of the invention:

The invention Ъ-meets a retrofocus wide-angle lens for photographic purposes with a relative aperture of 1: 2.4 to 1: 2.8 and a Feldwinkel'VVUschen 74 ° and 94 ° ^ which in particular for use on SLR cameras and for a large magnification range suitable is.

Characteristic of the known technical solutions

Pur the field of application Wide-angle objectives for retrofocus type for SLRs lenses are used, which consist essentially of an object-side scattering lens part with several controlling menisci, which turn their convex surfaces to the object, and an image-side collecting objective part, the aperture is housed in the collecting objective part. The majority of such lens constructions is general that the image aberration correction depends on the magnification. Specifically occurs in the aforementioned and distortion-corrected lenses whose Vinkelvergrößerung P-. less than 1, astigmatism and field curvature on according to the relationships:

ib '= is

= іг

_ ₂ _ 119 549

Where ζ ¹ = - f. ρ, ^{1 is} the objective lift , і b ¹ is the increase of the sagittal and 4b ' _m the increase of the meridional field curvature.

These aberrations occurring when focusing on near objects in the image field significantly disturb the image quality.

Objective constructions have therefore become known which make it possible to compensate for these aberrations in the case of a hair setting ((0).) In these cases, an airspace is simultaneously reduced in proportion to the objective stroke or a group of lenses is displaced within the optical system.

In DE 2 224 429 a 10-lens wide-angle lens is specified for a relative aperture of 1: 2.8 and a field angle of 2 (T = 84 ° there is an additional adjustment to change the field curvature.

US Pat. No. 4,025,170 describes a 7- or 8-lens wide-angle objective with a relative aperture of 1: 2.8 and a field angle of maximum 76, which contains a displaceable lens group in the object-side diffusing objective part for controlling the image aberration compensation.

The invention description DE 2 323 377 shows a 13-lens wide-angle lens with a relative aperture of 1: 3.5 and a field angle of 2ff = 102 °. By means of a displaceable lens in the image-side collecting objective part of the image error compensation takes place.

In the patent DE 2 413 471 and DE 2 413 473 11-wide wide-angle lenses with a relative aperture of 1: 3.5 and Feldwlnkel of 2S = 101 ° are described. For the purpose of controlling the aberration compensation, a variable air space is present in the object-side scattering object part bsw. introduced in the 'image-side collecting lens part, wherein

2t9 5 49

this airspace varies quite widely. Disadvantage of "known technical solutions in which there are a single or more movable lenses in the image-side lens part, is that these displacement members are very centering sensitive and des-ЬаіЪ cause manufacturing difficulties Disadvantage that because of the strong inclination of the main rays either the diameter of the front lenses grow strongly, or the range for the distance adjustment must be limited.

Unfavorable continues to be in such lenses, which require a separate airspace for the control of the image error compensation, that the number of separation points of the lens grows, which can give rise to the decentering. Furthermore, the known technical solutions allow only a relative opening of 1: 2.8 at. Field angles of 75 to -84 or of a maximum of 1: 3.5 at field angles of 2f <s100 °.

The economic production is made more difficult, since in general the known wide-angle lenses with aberration compensation consist of more than 7 lenses and thereby high-index crown glasses are used.

Object of the invention

It is a photo lens with aberration compensation for a relative opening of 1: 2.4 to 1: 2.8 created at the largest possible field angle of at least 74 ° v / ground, which also has lower production costs.

Explanation of the essence of the invention

The invention has for its object to construct a relatively fast wide-angle lens with aberration compensation, which contains as few lenses and largely avoids high-refractive Krongläser, and which for controlling the Bildfehleräusgleiches only one airspace; the aperture space, used.

if 9 549

This object is Eriindungsgemäß by a retrofocus wide-angle lens with aberration compensation with a relative aperture of 1: 2.4 to 1: 2.8 and a field angle of 74 ° Ms 94 °, consisting of an object-side lens part of low refractive power and the action einea reduced A telescope, and an image-side collecting objective part, wherein the air space separating the beiuen lens part contains the aperture and decreases linearly with the Objektivhub; achieved in that the image-side lens part seen in the light direction of a biconvex lens, a biconcave lens, a collecting meniscus and another image convex lens, all converging lenses turn their more curved surface to the image, and that the object-side lens part a biconvex lens, two scattering and einoi collecting Meniscus contains, with all menisci turn their convex surface to the object. The arrangement in the object-side objective part can be effected such that the biconvex lens is located between the two scattering menisci and the collecting meniscus adjoins the diaphragm space.

Table 1 shows the design data of such a wide-angle lens with respect to a focal length f = 1

 Furthermore, it is possible that in the object-side objective in the light direction of the collecting and the two scattering menisci follow each other and form a meniscus group, while the biconvex lens adjacent to the Blenäenraum, wherein between the menisci group and the biconvex lens a nearly afocal lens member in the form of an extremely thick and Object is inserted to be bent plane plate, which contains an oppositely bent and raised to the object scattering cement surface. In this case, the first lens with respect to the image-side lens part are fixed.

3579

_ ₅ _ 219 549

Tables 2 and 3 show the design data of such wide-angle lenses with respect to a focal length f = 1

 Because the aperture of the wide-angle lens. serves simultaneously to control the image error compensation, resulting in significant manufacturing advantages. It turns out that in comparison to the Objektivhub only small shifts of the aperture space for the image aberration compensation are necessary. As a result, extreme imaging scales can be realized.

In the objective examples given in Table 1, the material costs are extremely low.

The refractive indices of all Krongläser are down to one smaller than 1.63

 In the objective examples shown in Tables 2 and 3, high-index crown glasses with refractive indices above 1.7 are largely avoided, these lenses consisting of only 10 lenses.

For design reasons, it may be advantageous to keep the first lens fixed because of their size with respect to the image-side lens part.

Ausfuhrun ^ sbeispi e l

The invention will be explained with reference to drawings and tables.

Pig. 1 shows a lens sectional image of an objective according to the invention which corresponds to the design data given in Table 1

Pig. Fig. 2 shows a lens sectional image of an objective according to the invention which corresponds to the design data given in Table 2 or Table 3. Both objective examples consist of. an object-side 'objective part and an image-side objective part, _die separated from each other by the variable aperture space with the aperture BL »

2! 9 549

 In Pig. 1, the object-side objective part, seen in the light direction, consists of a scattering meniscus L, a biconvex lens Lp, a scattering meniscus

L-j 'and a collecting meniscus L .. 3 4

The image-side lens part is composed of a biconvex lens L 1 and a biconcave Lg, followed by a collecting meniscus L "and a final biconvex lens Lg

 The iris space 1 separating the two objective parts is a linear function of the magnification and thus of the objective displacement in accordance with:

I ₄ = 0, 1736 + 0.19 p. '

The variation of the Blenäenraumes 1. for controlling the image error compensation is only - 1§ % of Objektivhub ·

Ϊ5 Thus, extreme magnifications of p> * = -0.2 .... - 0.3 can be realized.

This wide-angle lens with a relative aperture of 1: 2.4 and a field angle of 2 ff = 74 ° is shown in Table 1 for a focal length f = 1.

Ϊ0 where г., to r- £ denote the radii of curvature of the respective lens surfaces, d- to dg. the thicknesses of the respective lenses.I., to 1 ". the distances between the lens elements, n _e the refractive indices of the glasses for the spectral line e with a wavelength of 54B nm and V _e the associated

> 5 Abbe ¹ see numbers.

In Pig. 2, the object-side objective part, seen in the light direction, consists of a collecting meniscus L, a scattering meniscus L 1, another scattering meniscus L 1, a lens element L in the form of a thick uuroh

Ю curved plane plate, which contains a convex diffusing surface to the object Kittfläche, and a bordering on the aperture space 1ц biconvex lens Lj-.

The image-side objective part includes a biconvex lens Lg, a biconcave lens L ,, a collecting Henislms Lg

І5 and a final biconvex lens Lg.

_ ₇ _ ZI9 549

The aperture space 1 separating the two objective parts is a linear puncture of the mapping dimension 3, namely: I ₅ = 0.1922 + 0.34. f>' in the example according to Table 2, bzyi. Ig = 0.1905 + 0,34'F "^'belm example according labeile In the case where the first lens L ₁ of the image-side Objektivtella remains fixed with respect to, the shift amounts for the lens elements Lg to L - together slightly larger, namely: 1 .. = 0.0096-0.37.6 'and I ₁ = 0.1922 + 0.37 × ρ' in the example according to Table 2, or 1., = 0.0048-0.37-ji 1 = 0.1990 + 0.37 × p>'in the example according to Table 3.

Again, the shifts are relatively small. They amount to - 34 % of the objective stroke or when holding the first lens L ₁ - 37% of the objective stroke, Thus, the aperture space I ₁ . even at extreme magnifications of, for example, β = -0.2 ... -0.3 still a sufficient size.

These two lens examples according to 'Table 2 and 3 are designed for a relative aperture of 1: 2.8 and a FeIdwinkel of about 94 °. Therein, T ₁ to r.jg denote the radii of curvature of the respective lens surface, d 1 to d _{1 o} the thicknesses of the respective lenses, I ₁ to I ₃ the spacings between the lens elements, η the refractive indices of the glasses for the spectral line e with a wavelength of 546 nm and - * _e the corresponding Abbe's numbers. In. The Objelctivbeispielen according to Table 1 relatively inexpensive glasses are used. High-breaking crown glasses are largely avoided. Only in the lens L "is a crown glass with a refractive index of 1.68 used.

In the objective examples shown in Tables 2 and 3, which consist of only 10 lenses, essentially crown glasses with refractive indices greater than 1.7 are not used. Hur in the embodiment according to the table is the lens L, a crown glass with a refractive index greater than 1.7.

219 549

Table!:

Focal length f = 1 0.0799 relative opening 1: 2 , 4 Cutting width s 0.44H Peld angle 26 "= 74 ° radii ¹ - = 1.321 .2219 refractive indices Ahbe'sche dicki 0.0035 ⁿ e Numbers * _e T ₁ »+ 1.8383 эп and 0.0972 1.5186 63.9 T ₂ = + 0.6745 Luftahstände .1441 r ₃ = + 7.6710 ^d 1 " .1181 1.6597 33.2 r ₄ = - 2.654 I ₁ a O, 1736 ⁺ r ₅ = + 4-4060 d ₂ = .2483 1.5186 63.9 r ₆ = + 0.5109 ¹ Z = .1466 r ₇ = + 0.8610 .1042 1.6167 54.9 r ₈ = + 7.3320 Io = 3 .1042 r _g = + 1.4948 ^d 4 ⁼ .1219 1.6229 60.0 r ₁₀ - - 0.8863 4 = 0.0035 r _{11 =} - 0.7613 .1285 1.7343 28.1 r ₁₂ = + 1.3373 ¹ S - r ₁₃ = - 1.6813 ^d 6 = 1.6810 54.7 r ₁₄ = - 0.6745 4 - T ₁₅ = + 13.8450 1.6152 58.4 r, _c = - 1.3041 4 = ^d 8 =

+ Control of the image error compensation: I ₄ = 0.1736 + 0.19 · fV

219 5 49

 - 9 -

Table 2: ι + 2.7683 = 1.815 .2740 relative opening 1: 2.8 АЪЪе'всЬе Focal length f = 1 + 6.9790 Thick and O.OO96 ⁴ Peldviinkel 2 & = 94 ° Numbers v _e Cutting width s ¹ + 1.3611 clearances .0913 refractive indices 6VP radii + 0.6.733 ^d 1 = .2691 ⁿ e + 1.3370 0,086.5 1.5914 54.7 ^Γ 1 ~ + 0.6351 d ₂ = .2788 r ₂ = - 3.9740. 0.4325 1.6810 52.9 ^r 3 ⁼ + 0.5196 ^d 3 ⁼ 0.2307 ^r 4 ⁼ - 3.4000 Ъ = 0.0096 1.7564 54.7 r = + 1.3664 .1538 41.0 ^r 6 = - 3.0850 d ₅ = 0.1922 ⁺ 1.6810 ^r 7 ⁼ + 2,0056 4 ⁼ 0.1682 1.5783 41.0 ^r 8 " - 0,8851 ^d 6 = 0.0625 - 0.8656 I ₅ = .2057 1.5783 55.7 ¹ yo = + 1.4904 .1009 - 3,1980 4 = .1418 1.5713 27.3 Ir ₁₂ = - 0.8824 ^d 8 = 0.048 ^r 13 ⁼ +10.0440 I ₇ = .1586 1.7617 60.0 - 1.6250 ^d 9 ^{= r} 15 ⁼ 1.6229 61.0 ^r 16 ^{= d} 1o = ^r 17 ⁼ 1.5914 ^r 18 ⁼ I ^- IO =

+ Control of the image error compensation :.

I ₁ «0.0096 (solid) and I ₅ = 0.1922 + 0.34 · ß ¹ I ₁ = 0.0096 - 0.37. p ¹ and I ₅ = 0.1922 + 0.37.

- ίο -

at 9 549

Table 3: + 2.6456 = 1.809 .2764 relative aperture 1: 2, Abbe ¹ see Focal length f = 1 + 6.6270 Thick and 0.0048 ⁺ Teld angle 26 "= 93.5 ° Numbers v _e Cutting width s ¹ + 1.4782 clearances 0.0952 refractive indices 61.0 radii + 0.6890 Cl ₁ - .3045 ⁿ e + 1.9169 ¹ I " 0.0857 1.5914 54.7 _r = + 0.6838 a ₂ » .2619 ^r 2 = - 9.0380 • "г- ⁼ .5329 1.6810 54.7 ^r 3 ⁼ + 0.4728 .2381 ^r 4 ⁼ - 8,5710 4 = 0.0095 1.6810 54.7 + 1.1338 .1428 38.4 ^r 6 = - 2,3898 H = O, 19O5 ⁺ 1.6810 + 1.8655. H ⁼ 0.1905 1.6028 52.3 ^r 8 - - 0.7926 ^d 6 = .0606 ^r 9 ⁼ - 0.7261 .1853 • f-, 5295 59.4 ^r 10 ⁼ + 1.5166 ^d 7 " .1095 - 3.3350 ч - .1381 1.5421 28.2 ^r 12 ⁼ - 0.8999 ^d 8 = 0.0048 ^r 13 ⁼ +14.0900 ¹ 7 = .1666 1.7436 54.7 ^r 14 ⁼ - 1.6626 dg = ¹ S = 1.6810 60.5 ^r 16 ^{= d} 10 ^{= r} 17 ⁼ 1.5661 ^r 18 ⁼

+ Control of the Bildfehlerausgleich.es:

I ₁ = 0.0048 (solid) and I ₅ = 0.1905 + 0.34. P 'or

I ₁ = 0.0048 - 0.37. (V and I ₅ = 0.1905 + 0.37. Β '

Claims (6)

21? 549 - -ff - Claim for invention: 1 · Retrofocus wide-angle lens with image compensation with a relative aperture of 1: 2.4 to 1: 2.8 and a field angle of 74 ° to 94 °, consisting of a objektseitigeri lens part of low power and the effect of a miniature telescope, and a. Image-side collecting lens part, wherein the air space separating the two lens parts contains the aperture and itself. linearly reduced with the Objektivhub, characterized in that the image-side objective part seen in the light direction of a biconvex lens, a biconcave lens, a collecting meniscus and another Biconvexlinse, all converging lenses turn their curved surface more to the image, and that the object-side lens part contains a biconvex lens, two scattering and one collecting meniscus, all menisci turning their convex surface towards the object. Objective according to point 1, characterized in that in the object-side objective part the biconvex lens is arranged between the base scattering menisci and the collecting meniscus adjoins the diaphragm space. 3 · Objective according to point 2, characterized by the design data given in Table 1, which are related to a focal length f = 1. , 25 4 · objective according to point 4, characterized in that in the object-side objective part in the light direction of the collecting and the two scattering menisci follow each other and form a meniscus group, while the biconvex lens adjacent to the aperture space, wherein between the menisci group and the biconvex lens a nearly afocal lens member in shape an extremely thick and to the object to be bent flat plate is inserted, which contains an opposite durchgebogene.und raised to the object scattering cement surface. 3579 219 549 5. Lens according to item 4, dadurch'gekennzeichnet that the 'first lens with respect to the image-side lens part is fixed. 6 »objective according to point 4 and point 5 _t characterized by the design data given in tables 2 and 3, which are related to a focal length f = 1. For this 1SsItS drawings