| 摘要 |
959,284. Albada finders for cameras. VOIGTLANDER A.G. June 10,1960 [June 10, 1959],No. 20615/60. Headings G2A and G2J. In an Albada viewfinder for a photographic camera, having its semi-transparent concave mirror carried on a lens element of the front member and separated from the carrier for the field-bounding frame by an air gap, and having provision for forming within the finder field an image of a part or parts in the camera, for example of an exposure meter pointer, an inclined reflector is carried on the side of the front member on a surface of a block of glass or transparent synthetic material which constitutes or is part of that member to receive light rays from the said part or parts when the finder is positioned in the camera, to re-direct the rays into the finder and to co-operate with a positive lens in the finder optical system so that the observer's eye sees an image of the said part or parts, substantially at infinity, within the total field of the finder. 'As shown (Fig. 3), an Albada finder comprises a front transparent lens 30 carrying a concave semireflecting mirror 32, and a rear transparent lens 31 carrying frame marks 33 which are imaged by the mirror 32 and the lens 31 at infinity. Rays from a pointer 40 or the like are reflected into the finder by means of a reflecting surface 41 and are imaged at infinity in the finder field by the combined action of lens element 39 and lens 31. In a modification (Fig. 4 not shown), the lens element is formed separately from the lens 30 and later cemented thereto. In a modification (Fig. 5), the front lens 60 is a combination of two lenses 61, 62 cemented together, and said lens element is formed by a lateral portion 63 of the lens 61. In a modification (Fig. 2 not shown), the reflecting surface 41 is formed on a lateral extension of the front lens, no lens element is provided, and the pointer is imaged at infinity by the action of lens 31 above. The invention may also be applied to Albada Finders having 1: 1 magnification as in Fig. 1 (not shown). Specification 958,029 is referred to. |
