GB926563A - Photographic camera equipped with view finder and exposure meter - Google Patents

Abstract

926,563. Photographic cameras. VOIGTLANDER A.G. May 15, 1959 [Sept. 19, 1958], No. 16783/59. Class 98 (1). A photographic camera having a built-in photo-electric exposure meter includes a unitary glass block Albada finder and an optical system including at least one mirror in the finder block and arranged to form a virtual image at infinity of the exposure meter needle and optionally of a follow-up pointer for that needle. As shown, a virtual image of an exposure meter needle 11 and a follow-up pointer 16 illuminated by external light through an opening in the camera cap 2 is formed in the viewfinder by way of a plane mirror 8, a positive collimating lens 8 and optionally a negative lens 88, and a plane mirror 6 cemented in a slot cut in the bottom of the finder block at about 45 degrees to the finder axis in the horizontal plane and at about 6 degrees to the vertical so that the mirror is tilted to bring the reflected image into the exit pupil of the finder. To improve the illumination of the needle and pointer in poor directional lighting, a lightcollecting plate having parallel prismatic wedges may be swung over the light opening in the camera cap (Figs. 1, 13a, 13b, not shown). Instead of employing a collimating lens 8, the virtual image of the needle and pointer may be formed by a curved full mirror surface which may be formed on the same surface as the semireflecting mirror 24 of the finder, i.e. on the finder objective 21, or a transparent surface adjacent to this (Figs. 10, 12, not shown), or a portion of this semi-reflecting lens surface may be made of a different curvature and made fully reflecting (Fig. 11, not shown). In these arrangements the needle and pointer are arranged directly above the finder block and the image is introduced into the block by a plane mirror in the block perpendicular to the vertical plane and inclined to the optical axis in that plane at 45 degrees plus about half the angle which the useful bounding finder rays make with the axis. In a further modification (Fig. 14, not shown), the needle and pointer are parallel to and illuminated through a window at the front of the camera cap and a real image is formed by a lens on the mirror in the finder block which introduces the image into the finder field, a collimating curved mirror being formed on the rear face of the finder objective. In a variation of this last modification, the needle and pointer may be arranged with their axes of rotation perpendicular to that specified, a further mirror being provided to bring an image of them into the finder.