DE568058C

DE568058C - Setting viewfinder for photographic cameras

Info

Publication number: DE568058C
Application number: DEG80652D
Authority: DE
Original assignee: HUGH IVAN GRAMATZKI
Current assignee: HUGH IVAN GRAMATZKI
Publication date: 1933-01-13

Description

Einstellsucher für photographische Aufnahmekameras Gegenstand der Erfindung ist eine Verbesserung der Einstellvorrichtung gemäß Patent 565 868.Setting viewfinder for photographic cameras is the subject of the Invention is an improvement of the adjustment device according to patent 565,868.

Bei Einstellvorrichtungen der im Hauptpatent beschriebenen Art bildet das Okular a (Abb. i) die Eintrittspupille E mit dem Fangspiegel b in A ab. Dadurch hat man beim Durchblick einen kleinen, verwaschenen dunklen Fleck im Gesichtsfeld, der als störend empfunden und gegebenenfalls durch seitlichen Einblick beseitigt werden kann. Die Anbringung einer diesen Fleck verdeckenden Einstellmarke in der Brennebene d hat den Nachteil, daß die genaue Einstellung des Bildes in der Ebene der Einstellmarke infolge der Akkommodationsbestrebungen des Auges mißlingt. Diese Schwierigkeiten lassen sich durch eine Anordnung gemäß der Erfindung beseitigen, nämlich durch Anbringung einer Mattscheibe feiner Körnung in der Einstellbrennebene, am besten von einer solchen Größe, daß das ganze Gesichtsfeld ausgefüllt wird. Nun vermag das Okular nicht mehr den Fangspiegel b in A abzubilden, der störende Fleck fällt fort, und gleichzeitig ist die Einstellsicherheit gewährleistet. Die Mattscheibe c kann, wie in Abb.2, auf einer besonderen, dem Hauptspiegel e vorgesetzten Platte angeordnet werden. Der Hohlspiegel braucht nicht durchbohrt zu werden; es ist lediglich notwendig, die Versilberung in der Mitte zu entfernen.In the case of adjustment devices of the type described in the main patent, the eyepiece a (Fig. I) images the entrance pupil E with the secondary mirror b in A. As a result, when looking through, one has a small, washed-out dark spot in the field of vision that is perceived as annoying and can be removed if necessary by looking from the side. The attachment of an adjustment mark covering this spot in the focal plane d has the disadvantage that the precise adjustment of the image in the plane of the adjustment mark fails as a result of the eye's tendencies to accommodate. These difficulties can be eliminated by an arrangement according to the invention, namely by attaching a fine grain focusing screen in the focal plane, preferably of such a size that the entire field of view is filled. Now the eyepiece is no longer able to image the secondary mirror b in A , the disturbing spot disappears, and at the same time the setting security is guaranteed. The focusing screen c can, as in Fig. 2, be arranged on a special plate in front of the main mirror e. The concave mirror does not need to be pierced; it is only necessary to remove the silver plating in the middle.

Claims

PATENT CLAIMS: i. Device for focusing objects in the imaging plane of a photographic lens according to patent 565 868, thereby characterized in that the image is taken from the perpendicular to the optical axis of the main mirror (e) arranged secondary mirror (b) is thrown back onto a ground glass screen (c) which the image is viewed with the help of an eyepiece.

2. Adjustment device according to claim i, characterized in that the ground glass between the with one Real imaging main mirror (e) and the secondary mirror (b) provided with a view is arranged.

3. Adjustment device according to claim i and 2, characterized in that that the secondary mirror (b) is inclined to the optical axis of the main mirror (e) and this has a corresponding eccentric view to the parallax compensate. q ..

Adjusting device according to claim i, characterized in that use of a ground glass made a little transparent by subsequent polishing finds.

5. Adjusting device according to claim q., Characterized in that one chemically produced semitransparent ground glass is used.