DE2125352B - Afocal lens system with continuously variable magnification - Google Patents

Description

Γ, η =

^r I2 =

83.5 di = 2.0 d _s n ₂ = 1.74077 Ver V ₁ = 27.7 30.0 d ₂ = = 1.60738 size r ₂ = 56.7 -940.0 d ₃ = 5.5 2.17 tion 34.5 d ₄ = 0.2 16.14 please refer = 1.51742 0.472 v ₃ = £ 52 1100.0 d ₅ = 4.4 24.83 ; below 1,000 -65.8 d _b = variable, _v = 1.74400 2.016 r ₄ = 44.9 17.5 d, = 1.5 -78.0 d ₈ = Z5 = 1.69350 V ₅ = 53.4 10.2 1.0 please refer , = 1.74077 v _b = 27.7 102.3 d ₁₀ = 4.0 n- : below -98.0 you = variable. c = 1.78472 »7 = 25.7 98.0 you = 1.8 : below 41.8 you = variable, = 1.69350 > - "= 53.4 -418 1.8 d, ₂ 22.82 Shortest Focal length 1.65 Medium Focal length 5.48 Longest Focal length 5.02 0.83 0.98

where the refractive index η and the Abbe number ν are related to the d-line of helium.

The invention relates to an afocal lens system with continuously variable magnification for Cameras, especially film cameras, e.g. B. for 8-mm-Schmalnlmc.

The invention creates a new and improved varifocal or zoom lens for cameras, its spherical aberration and astigmatism move within very narrow limits and which are mass-produced can be produced.

The optical lens system according to the invention has four groups ν η lenses in a known manner: the first group is positive, the second and third group are negative, the fourth group is again positive. The collecting first group consists of a negative meniscus cemented with a biconvex lens is, and a positive meniscus; the second group consists of a biconcave lens and a cemented limb an anterior biconcave lens and a positive meniscus; the third group is a biconcave Lens and the fourth group a biconvex lens. The first group is for setting the object distance movable; the second group, a varia'or, is linear to the change in magnification movable; the third group is a compensator to mechanically compensate for the change in magnification, caused by the displacement of the variator; the fourth group is used for the lens to make an afocal system. The two radii of curvature of both surfaces of the concave lens

the third group are the same as those of the biconvex lens in the fourth group, so that these lenses can be mass-produced with little effort. When these lenses are used together with the first and second lens groups, as will be described in more detail below, the spherical aberration and astigmatism can be kept within very narrow limits and a flat image can be formed.
F i g. 1 shows a longitudinal section through an afocal lens system with continuously variable magnification according to the invention.

F i g. 2A, 2 B and 2 C show the diagrams of the spherical aberration, the astigmatism and the distortion of a focusing lens system which, together with the afocal lens system with continuous magnification change, according to the method shown in FIG. 1 is used.
F i g. 3 A1,3 B1 and 3 C1 show the diagrams of the

spherical aberration of astigmatism and distortion of the entire lens, consisting of the afocal lens system and the focusing lens system according to FIG. 1 or 2 if the total focal length is the shortest

^p i g. 3A2, 3B2 and 3C2 show the corresponding graphs of the optical errors when the total focal length has a medium value. Figs. 3A, 3, 3 B 3 and 3 C 3 show the corresponding graphs of the optical errors when the total focal length is the longest

In the system described after the invention is specified in any length unit, because the mode of action is achieved with any length unit, as long as the numerical values below remain unchanged.

The afocal lens system with continuous magnification range according to the invention is characterized by the following manufacturing data marked:

r ₂ =
r ₃ =

r ₉ =

Για =

83.5

30.0 -940.0

34.5 1100.0 -65.8

17.5 -78.0

10.2

102.8

-98.0

98.0

41.8 -41.8

dt = 2.0 H ₁ = 1.74077

d ₂ = 2.0 n ₂ = 1.60738

d ₃ = 0.2

d ₄ = 4.4 n ₃ = 1.51742

d ₅ = variable, see below

d _b = 1.5 η _Λ = 1.74400

ii ₇ = 2.5

d ₈ = 1.0 n ₅ = 1.69350

d, = 4.0 H ₆ = 1.74077

d _l0 = variable, see below

<f _tl = 1.8 n ₇ = 1.78472

di 2 = variable, see below

ά. _Λ = 1.8 M ₈ = 1.69350

V ₁ = 27.7 v ₂ ---- 56.7

V ₃ - 52.2 v ₄ = 44.9

v ₅ = 53.4. · «, = 27.7

v ₇ = 25.7 v ₈ = 53.4

d, ₂ Ver d, ₀ size 1.65 tion 22.82 5.48 0.472 5.02 0.83 1,000 0.98 2.016

Shortest focal length ... 2.17 22.82 1.65 0.472

Medium focal length ... 1614

Longest focal length 24.83

v / obei means

r with index is the radius of curvature of the surface marked with this index,

d with index is the glass thickness of the lens marked with this index or the length of the air gap on the optical axis,

η with index is the refractive index of the lens marked with this index, measured with the d-line of helium, the numbering takes place continuously from the front to the rear end.

ν with index is the reciprocal of the divergent power of the ^s ° lens marked with this index. The refractive index and the dispersive power are measured with the rf line of helium.

The afocal lens system according to the invention with continuously variable magnification has a magnification between 0.472 and 2.016.

A prism P is interposed between the afocal lens system with continuously variable magnification and the focusing lens system L _Af , the hypotenuse surface of which is semipermeable or semitransparent. It is used to deflect the reflected light onto the viewfinder of a single-lens reflex camera. The air distance between the fourth group IV and the center of the prism P on the optical axis is 0.5: the thickness of the prism P is 8.5; the air distance between the center of the prism P and the focusing lens system L _M , in which its diaphragm S is mounted, is 4.0. The values of the focusing lens system are: / = 18.0656, 3F = (focal back focus) = 13.128 and relative aperture 1: 1.8 with the optical errors according to FIGS. 2A to 2C. The optical errors of the entire objective are shown in Fig. 3A to 3C3. In the following table, F _{w means} the shortest focal length of the entire lens, F the mean focal length and F _r the longest focal length. The Seidel sums have the following values:

Focusing

Total lens systems

F _w = 8.5275
F ₁ = 18.0656
F τ = 36.4 i 44

0.3400

1.1668
0.5393
0.2043

2SII 0.1797

SHI - 0.0436

0.2222
0.2682

0.2115 12460

rs iv

0.4962

0.0504 0.111. 0.0716 0.2300

0.4309

iSV 0.2833

"08482" 0.1914 0.4507

whereby

SI = Seidel sum of spherical aberration, SII-- ^ eidel sum of coma, SIII = Seidel sum of astigmatism, SIV = Seidel sum of field curvature, SV = Seidel sum of distortion.

The invention thus creates a zoom lens which contains four lens groups. The third group will formed by a biconcave lens, both surfaces of which have the same radius of curvature as the fourth group is formed by a biconvex lens, the two surfaces of which are also the same Have radius of curvature. When combining this third and fourth group with the first and second Spherical aberration and astigmatism can be kept within very narrow limits and a flat group Image.

1 sheet of drawings

Claims (1)

Afocal lens system with continuously variable magnification, consisting of four lens groups, a collecting first group consisting of a negative meniscus, which is connected to a biconvex Lens is cemented, and a converging meniscus-shaped further lens, a second Claim: Group of a biconcave lens and a cemented member from a front biconcave lens and a positive meniscus, a third group of a biconcave lens and a fourth Group of a biconvex lens, labeled through the following production data: