DE1678151U - ADJUSTMENT DISC TO CONTROL THE FOCUSING OF PHOTOGRAPHIC CAMERAS. - Google Patents

Description

H281518HI5.54

• ■ '....' ο

to. Pa, 969 Stuttgart, April 4, 1950

"Sinste11scheibe to control the focus photographic cameras "

It has already been suggested to control the focus of photographic cameras * in the middle of the Liattscheiba - one in z ?. ^A converging lens cut in half or four parts must be attached in such a way that their parts are displaced from one another. The parts then have a prismatic effect and result in parallactic image displacements that compensate for each other as soon as the prismatic elements are in the plane of focus of the image Converge observer. At the joints between the lens parts, there are some differences in the thickness of the glass, which the eye perceives as an annoying line with the Sinste1-Ie 2i. and if a planoconvex lens is used, they do not necessarily coincide with the planar surface. As a result of these circumstances, the image properties of the known setting disks mentioned are adversely affected and the accuracy of the setting is impaired.

This Geesthacht parts are avoided by the! Inflation that a Ctufenlinse used for said purpose as a divided lens, you can in this case themselves form the shim with its grid-like surface or the _v placed in a conventional manner occurs when using such a lens

the parting line between the mutually offset parts is no longer noticeable in appearance and their main levels practically coincide the grid level together "

The converging lens can be designed as a spherical stepped lens (Fresnel lens). Another option is this _? to design the converging lens as a cylindrical stepped lens made of parallel, straight ribs. This type deserves preference, since it is much easier to manufacture than the spherical stepped lens. The same applies to an arrangement in which the cylindrical stepped lens is superimposed crosswise by a second to brighten the image corners.

The offset of the sections of the Fresnel lens against each other gives the best results if it is half the size of the lens opening. ₇ is therefore advantageous in Verv / ending of lenses with adjustable aperture, so especially in single-lens reflex cameras, the parts of the Fresnel lens to each other slidably to arrange · to the displacement of the respective aperture to adjust.

A particularly expedient method for the production of thawed and partially offset Fresnel lenses is achieved if their form is chosen so that they can be molded or cast in one piece from a plastic, transparent plastic compound by means of a corresponding die. This also prevents the joints between the lens parts becoming more prominent. The die, by means of which these cylindrical stepped lenses are made, expediently consists of a package of razor-thin steel sheets, one end of which corresponds to the surface to be produced, Z ₉ B, cylinder

the flat, is ground, and the package is aligned with the protruding edges of the individual sheets according to a plane that is mainly perpendicular to the layering. A very fine subdivision can thus be _{achieved, i.e. of about O 7} O.D mm and below.

Based on the drawing, im. following the! inflation in several Examples explained.

The shim after Fi ^. 1 consists of the two halves 1 and 2 of a Fresnel lens which are offset from one another by the amount e (= l / 2 lens afnun £;) »Figs. 2 and 3 show the sections according to II - II and III - III of FIG. 1 in a coarsened manner. If Έθώά is not in focus, image B of the object is divided; / ax the fugue of the lens halves and the ropes are shifted against each other. To adjust the focus, the objective and the adjusting disk have to be adjusted against each other until, similar to a cross-sectional rangefinder, the parts fit together in one image.

In Fi ^ · 4 a cylindrical stepped lens is shown, the halves 3 and 4 again by an amount e (= 1/2 lens opening) are offset from one another. The focus occurs in the same way / v / ie- in the first example. FIG. 5 shows the same arrangement as FIG. 4, only the first is still here cylindrical step lens a second cylindrical step lens superimposed crosswise, this gives a similar brightening the corners of the image, as when using a spherical one Fresnel lens. The manufacture of such a

Claims (5)

PA281518 * -3.5.C4 {^ drischen Fresnel lens is, however, significantly simpler. The second superimposed Fresnel lens can also be divided and shifted in its parts wagerschten object edges can be adjusted. Correspondingly, of course, the. Fresnel lens according to Fig. 1 instead of ζ v / ei parts divided into vior parts. According to Fig. 6 and Fig. 7, a stack of razor-thin steel sheets (approximately 0 ^ 06 mm thick) 5, 5 ', 6 "... ... ground down according to a curved surface (circular cylinder surface 7) corresponding to the desired step profile. Then the protruding edges 8, 8 ', S1' <>. The ribbed profile obtained in this way corresponds to the surface of the step body to be formed. In order to simplify the grinding, the stack can also be prepared according to a curved surface 10 before grinding. To produce dies for stepped bodies with wedge ribs delimited by flat surfaces, the stack of sheets, after possibly having been prepared according to an inclined surface, is ground down at an angle and, as above, aligned according to a plane perpendicular to the layering 1. Focusing disc to control the focus of photographic cameras based on the compensation of the parallactic
. Image shift which results in a converging lens consisting of mutually offset parts, characterized in that the converging lens is a divided stepped lens which is offset in its parts. 2 "Focusing screen according to claim 1, characterized in that the safflower is divided by the middle and in its parts. (I _f 2) offset © spherical step lens' (Fresnel lens) .is (FIgn «1 *" 3) ·; - Is ~ converging lens as straight cylindrical stepper lens consisting of parallel ridges and divided by the line einsr your to this course .: eilstücken and in their £ (3,4) offset - 3 · shim according to claim 1> characterized in that d ± - (FiS. '4) .- ~ 4-. _Y shim according to claim 3, characterized in that the cylindrical Fresnel lens is overlaid by a second crosswise CFIG x 5) " 5 · Sinstellscheibe according to claim 1 or one of the following claims ^ characterized _? that the parts of the lens can be displaced against each other along their separating eyes, 6, "Shim according to claim 1 or one of the following claims, characterized in that it is by means of a decision ■ speaking Katrize ₇ of a plastic transparent plastic mass Präg bar or pourable. ?. Device according to claims 3 and G, characterized in that the die from a package of rasierkling endünnen steel sheets iS _r 6 * 6 "-,.) Besxeht _r sanded whose one end face by a suitable surface (ζ · 3 · Zvlinderfläche 7) and then the "package with the protruding edges (3, 3 ', 3' ¹ ... of the individual metal sheets) is aligned with a plane (9) that is primarily perpendicular to the layering (? ign. ο u."