DD224413A1 - PHOTOGRAPHIC RECORDING LENS WITH BACKLIGHT - Google Patents

Abstract

The invention relates to a camera lens compact design with rear panel, which detects an image angle of 65 at a opening ratio of 1: 2.8. The invention is to be avoided in the realization of the subject invention, the use of extremely high-refractive Glaeser. This is achieved by carrying out the five-lensed, four-limbed optical system according to the numerical example of one of the two points of the claim of the invention. figure

Description

Dresden, April 16, 1984

Title of the invention

Photographic picture lens with rear panel

Field of application of the invention

The invention relates to a photographic recording lens compact design with Hir.terblende for the format 24 x 3ö, which is characterized with an aperture ratio of 1: 2.8, an angle of view of 65 ° and the lenses are arranged so that seen in the light incident direction are two positive menisci each of which has its curvature directed toward the object and which is followed by a biconcave lens facing the image with the more curved surface, followed by a cemented convex putty member consisting of a biconvex lens and a negative meniscus which terminates the system as the last lens ,

Characteristic of the known technical solutions

Known lenses of the type described above with rear panel, which are used in Kompaktkämeras, have at an aperture ratio 1: 2.8 image angle up to 60 °. In order to achieve a low height, short focal lengths are preferred in these lenses. Shorter focal lengths with a constant image format, however, cause an increase in the angle of view, which in turn causes an enlargement

the diameter of the frontal lenses entails to eliminate annoying vignetting. In addition, an increase in the diameter of the front lens causes an increase in the lens thicknesses, which in turn an unfavorable. constant influence on manufacturing and economic issues.

Object of the invention

By applying the invention, the realization of a short focal length compact lens while avoiding extremely high refractive glasses is possible.

Presentation of the essence of inventing

The invention has for its object to provide a five-lensed, four-element lens with rear panel for a compact camera, which has an angle of view of 65 ° at a Öffnungs.verhältnis of 1: 2-, 8.

The object is achieved in that the execution of the lenses of the lens according to the numerical example of 'one of the two points of the claim of the invention. It was found that the design data up to + 0.2 / p at both surface powers Δ η /, up to

+ 0.02'f at the vertex distances d of the lens surfaces, up to + 0.02 for the refractive indices η and up to + 2 for the Abbe numbers.

embodiment

The invention is explained below with reference to the drawing.

The lens has an aperture ratio of 1: 2.8 and has an image angle of 65 °. The optical system shows a five-lens, four-membered structure.

In the direction of light, there are two positive menisci at first, which turn their curvature towards their object. They are followed by a biconcave lens, which faces the image with the more curved surface, and is adjoined by a cemented element provided with convex surfaces on both sides. This cemented component consists of a biconvex lens and a negative meniscus , which is the last lens facing the image. Optics systems having a lens arrangement as described herein are well suited for a

10 · dry construction. A compact design is of great importance for a lens with rear panel, since the frontally located lenses are not distended too much in diameter, which would make it difficult to correct the aberrations. In order to keep spherical and komatical aberrations small, the two first lenses, which are on the side of the longer radiation distance, are formed as positive menisci, which turn their curvature towards the object. In order not to overstress the curvature surfaces, these lenses mostly consist of glass types with refractive indices of more than 1.76. The optical system must have a very compact construction in adaptation to the camera, in which the optical length does not exceed 1.12 times the focal length, and the Schreitelmaß is not greater than 0.4 times the focal length. Furthermore, the task contains that only glasses are used whose refractive indices are less than 1.76. Due to the demand for the extremely short peak size lens thicknesses and air gaps must be such that they represent mainly minimum sizes. Thus, there is hardly a possibility to correct aberrations by varying lens thicknesses and air gaps. Since no glasses with higher refractive indices are used, the glass selection does not have any decisive influence on the correction state of the system. The correction of the aberrations is essentially done by the area

Breaking forces, which are characterized by the radii of curvature of the lens surfaces in fixed media. In particular, spherical aberrations can be corrected by the radii of surfaces 1, 3, 5, and 6, while the curvatures of surfaces 5, 7, and 9 act on field curvature, astigmatism, and coma.

It has been found that a good optical performance is achieved mainly when the relevant radii are adjusted so that the following conditions are observed with regard to the surface powers:

1. 1.8 f ^ ί 1 ⁺ Jg 3 <2.1 f '·

2. - 0.35 f - -? 5 - -0.25 f

3 - 2.5 f ί J ₆ ^ -2.1 f

4-1 f 'sf ₇ s 1.5 f 5- 0.25 f = r J ~ ₉ ^ 0.35 f Here, f is the lens focal length, _ ^ ~ with the corresponding surface index the respective surface refractive power. If these conditions are met, lenses with an aperture ratio of 1: 2.8 and a short overall length can be calculated for use with a rear panel, which has an angle of view of 65, the lenses consisting only of glasses whose refractive indices are less than 1.76. A cross-sectional drawing and two numerical examples in Tables 1 and 2 characterize lenses constructed according to the invention at an equivalent focal length 1, wherein the specified design data with respect to the surface powers δ -n / r up to + 0.2 / f, with respect to the peak distances d each up to + 0.02. f, with respect to the refractive indices η up to + 0.02 and with reference to the Abbe numbers, can deviate from ice to + 2. The radii of the curvature surfaces, d the vertex distances between the lens surfaces, η the refractive indices related to the spectral line s ( X = 546.1 nm) and /? the corresponding Abbe numbers for color dispersion.

Table 1

Focal length f = 1 0.3546

Aperture ratio 1: 2.8

^r 1 =

^r 2 ⁼

^r 3 ⁼

Ci ₁ = 0.0459 d ₂ = 0.0099 d ₃ = 0.0588 d ₄ = 0.0363 d ₅ = 0.0336 dg = 0.0270 d ₇ = 0.114 d ₈ = 0.0339

.4442

.3722

r ₄ = 0.6696 T ₅ = - 2.2075 r ₆ = 0.3125 r _? = 0.6996 r ₈ = - 0.3913 v _s = - 1.6963

Table 2

Focal length f = 1 ^r 1 = ° ' ³⁸²⁵ Cl ₁ = 0.0642 r ₂ = 0.4993 ^ _{= OjOO74}

d ₃ = 0.0696 d ₄ = 0.0451 d ₅ = 0.0285 'dg = 0.0277 d ₇ = 0.1210

^r 7 =

^r 8 = "

0.3603 0.5714 2.3834 0.2965 0.5207

O, O343 = 1.75638

= 52.9

n ₂ = 1.75638 v? ₂ = 52.9 n ₃ = 1, 67764

= 32.0

= 1.75638 v> = 52.9

n ₅ = 1, 57126 \> ₅ = 55.7

Aperture ratio 1: 2.8 G ₁ = 1.73444 V ^ ₁ = 52.0 n ₂ = 1.73444 n ₃ = 1, 70445

n ₄ = 1, 73444 n _r = 1, 57086

? ₂ = 52.0 ^? ₃ = -29.8

^? 4 = 52.0 ^? c = 62.9

= - 2.1650

Claims (3)

Invention s ans p me 1. Photographic recording lens compact design with rear panel, which at an aperture ratio of 1-: 2.8 distinguishes a picture angle of 65 ° and des-5. sen lenses are arranged so that seen in the direction of light incident two positive menisci each turn their curvature to the object and followed by a more curved surface with the image facing biconcave lens, followed by a provided on both sides with convex putty member, which consists of a Biconvex lens and a negative meniscus is the last lens terminates the system, characterized by the following numerical values: Table 1 Focal length f = 1 aperture ratio. 1: 2.8 r ₁ = 0.3546 _d ^ _{= 0} 0459 n} ^ ₌ -1.75638 V ₁ = 52.9 T ₂ = 0.4442 ^ _{a 0} ^r 3 ⁼ °> 3722 _d ^ ₌ o, O588 n ₂ = 1.75638 v> ₂ = 52.9 ^r 4 = ° ' ^{οο: 7α} d ₄ = 0.0363 V ₅ = - 2.2075 _{d =} o, O 336 n ₃ = 1.67764 O ₃ = 32.0 ^r 6 = ° ' ³¹²⁵ d ₆ = 0.0270 r _? = 0.6996 _{d =} 0.1140 n ₄ - = 1.75638 ^ ₄ = 52.9 r ₈ = 0.3913 _{ds =} o, O339 n ₅ = 1.57126 ^> ₅ = 55.7 r _g = - 1, 6963 2. Photographic taking lens of compact design, characterized by numerical values listed below: Table 2 Focal length f = 1 aperture ratio 1: 2.8 ^r 1 ⁼ ° ' ³⁸²⁵ CL ₁ = 0.0642 U ₁ = 1.73444 ^ ₁ = 52.0 = 0.0074 n ₂ = 1.73444 V ₂ = 52.0 n ₃ = 1, 70445 v> ₃ = 29.8 n ₄ = 1.73444 v \ = 52.0 r "= - 0.3353 _, _{Λ Λ} ^ ^ _{n = 1j57} o86 ^ c = 62.9 3. A photographic lens according to item 1 and 2, characterized in that the design data up to + 0.2 / f at the surface powers Λ n / r, up to + 0.02. f at the vertex distances d of the lens surfaces until ZLi + 0.02 at the refractive indices η and up to + 2 at the Abbe see numbers abv.'eichen can. (See 1 page drawing)