DE635072C - Photographic recording chamber with top viewfinder and optical light meter - Google Patents

Description

GERMAN EMPIRE

ISSUED ON SEPTEMBER 9, 1936

REICH PATENT OFFICE

PATENT LETTERING

CLASS 57a GROUP 9

Patented in the German Empire on January 22, 1935

The invention relates to an optical light meter and its loose connection with the lens of a mirror finder, in such a way that the observation of the known art under the influence of the light visible comparison fields of different intensity due to the mostly at right angles the field lens arranged to the viewfinder lens takes place. This process is optical Light meters almost generally brought about by the fact that the relevant comparison fields (with numbers or the like) can be viewed through an eyepiece and thus appear enlarged. According to the invention results is particularly suitable for those photographic chambers in which there is a relatively large mirror viewfinder above the taking lens is arranged, a substantial simplification in that on the aforementioned eyepiece. can be dispensed with entirely; at its place is the field lens of the reflex viewfinder (Fig. ι and 2). The light meter becomes considerably easier for the present purpose, because it now consists essentially of the carrier of the Comparison field and a device that lawfully weakens the incident light, z. B. a continuous wedge of circular shape and one for the present case expediently concentric arrangement of code numbers.

Condition for the new facility is. that the carrier of the comparison fields in The focal point of the field lens lies so that the rays emerging from this run parallel. Small deviations from this are of course irrelevant, so that it z. B. is possible without disadvantage, the parts of the light meter in front of or behind the To arrange the lens of the viewfinder.

The arrangement is such that the exposure meter points to the lens of the Viewfinder can be plugged or hinge-like connected to the same. It is as a result The favorable dimensions of the parts of the exposure meter in question are also easily possible to do this to provide close behind the lens of the viewfinder, so that it can be, for. B. on a slide or the like. Optionally switched into the beam path of the viewfinder and when in use can be removed from this during recording.

The invention is illustrated in the schematic drawings, namely:

Fig. I a vertical section through a camera with a light meter behind the Viewfinder lens,

Fig. 2 is a top view of the camera according to Fig. 1,

Fig. 3 is a vertical section through a camera with mirror viewfinder with in front of the

*) The patent seeker stated as the inventor:

Karl Pritschow in Braunschweig.

Claims (4)

Viewfinder lens lying light meter and matted surface of variable position between the lenses of the field lens
α is the housing of the camera with
Taking lens δ; above this is that
viewfinder arranged with the lens *? ' and the mirror <d inclined at 45 ° to its optical axis and the field lens e. The optical exposure meter / can either be attached to the mount of the viewfinder lens c or, as shown in Figs. 1 and 2, be arranged in a displaceable slide behind the lens £. When looking into the viewfinder from above, due to the increased effect of the lenses, one sees the individual comparison fields Z _{1 of} the exposure meter / as well as a row of corresponding numbers / ₂ arranged concentrically to one another. In Fig. 3 another zo construction is shown, namely for a viewfinder camera with a ground glass or a matted surface of any type, which can be optionally brought into the beam path of the viewfinder. So is z. For example, a rollable film k is suitable which, in addition to a matted surface of the size of the field lens <? I and e _{2, has} a similar but transparent surface. Of the . Exposure meter / is mounted in a hinge-like manner in front of the lens at m on the camera housing, so it can be switched on or off relatively quickly. In this case, the field lens is designed in two parts, e _t and e ₂ , and the matt surface used for adjustment can be removed from the beam path of the viewfinder by winding or unwinding ^{with the aid of known mechanical means 1} , Λ and i, so that then the effect of the lens supervisor is achieved again,
There are of course a number of other possibilities to observe the details of the comparison field of the exposure meter / from above with the aid of a lens which is in direct connection with the camera but not with the exposure meter. j, claims: > I. Photographic recording chamber with viewfinder and optical exposure meter, characterized in that the important measurement components of the optical exposure meter (/), in particular the comparison field (Z ₁ ), are arranged directly in front of or behind the lens (c) of the viewfinder , in such a way that the comparison field (/ _x ) of the exposure meter (/) comes to lie approximately in the focal point of the field lens (e) of the viewfinder and so the reading of the brightness values through the field lens [ei) of the viewfinder can be increased. 2. Photographic recording chamber according to claim 1, characterized in that the carrier of the comparison field (/ _x ) of the optical exposure meter (/) from the front onto the mount of the viewfinder lens (c) can be loosely attached or also through a joint (m) with the camera housing (a ) or the viewfinder lens (c). 3. Photographic recording chamber according to claim 1, characterized in that the comparison field (/ _x ) of the optical exposure meter is attached behind the viewfinder lens (c) so that it can be switched off. 4. Photographic recording chamber according to claim I, characterized in that the field lens (e) is designed in two parts (ef, e ₂ ), such that an elastic visor [k) is slidably guided between its flat surfaces, one half of which is the size of the The field lens is frosted, while the remaining part has a clear view for the observation of the light meter. 1 sheet of drawings