Device for indicating exposure factors in the viewfinder of a single lens reflex camera

Claim 2

A single lens reflex camera having means for adjusting the values of at least one exposure factor, the combination comprising a viewfinder for observing an object to be photographed through the camera lens, the finder comprising a focussing screen having a step portion at one edge thereof, a frame having an aperture for the field view, the frame overlapping the screen, a reflecting member for directing the light passing through the camera lens to the screen, a window formed in the frame in a position overlapping a plane substantially parallel to the screen surface and witHin the reflecting light path of the reflecting member, an elongated marked member having indicia for indicating the value of the exposure factor and having a projection at a central portion thereof, the member being slidable along the step portion of the screen within a space defined by the frame and said parallel plane, a driving means for moving the indicia member forwardly and reversely, the driving means comprising a thread extending along the step portion and connected to said projection of the indicia member, at least one reel for taking up the thread, an operating member for rotating the reel forwardly and reversely, the operating member being controlled by the operation of adjusting means for the values of exposure factor, a biasing means for biasing the indicia member in the direction opposite to the direction of take up of the thread by the reel, and an auxiliary reflector arranged at a position outside the finder light path between the reflecting member and the screen and having a reflecting surface inclined to direct the light rays passing through the camera lens at substantially the central portion of the exit pupil.

Claim 3

A single lens reflex camera according to claim 1, in which at least one surface of the step portion is formed as a guide surface for the indicia member.

Claim 4

A single lens reflex camera according to claim 1, in which the indicia member has a plurality of small openings in the projection formed thereon in alignment with its direction of movement, the thread passing through said small holes to secure the member to said thread.

Claim 5

A single lens reflex camera having a viewfinder including an eyepiece, a focussing screen and a viewing mirror for reflecting the light rays passing through the camera lens onto the focussing screen to be viewed through the eyepiece and having means for adjusting the value of at least one exposure factor, the combination comprising a pair of spaced polarizing plates having their respective axes angularly disposed relative to each other, said pair of plates being in the path of light rays reflected by the viewing mirror, exposure indicia provided on one of said plates, a member of rotatable polarizing characteristics movable in a path between said polarizing plates, and means for positioning said member by said adjusting means to provide illuminated indicia of the exposure factor value set by the adjusting means, the focussing screen being formed with a step portion along one side thereof, at least one of said polarizing plates overlaying said step portion, said one plate being provided with said exposure indicia, and said member being movable between said polarizing plates along the path determined by said one plate, the means for positioning said member includes a spring biased barrel and a reel disposed on opposite sides of the focussing screen and adjacent to the step portion formed thereon, a thread secured at its ends to said barrel and said reel, said member being secured to said thread, and a gear arrangement for rotating said reel by the adjusting means for moving said member by said thread; a frame having an aperture for the field of view, the frame overlapping the focussing screen and further formed with an elongated window above the step portion in the focussing screen and said polarizing plates, the indicia provided on one of said plates being viewable through said window, and an auxiliary reflector provided at a position outside the light path between the viewing mirror and the screen, the auxiliary reflector having a reflecting surface inclined to direct the light rays passing through the camera lens substantially from the central portion of the exit pupil of the camera lens to the window.

Claim 6

A single lens reflex camera having a viewfinder including an eyepiece, a focussing screen and a viewing mirror for reflecting the light rays passing through the camera lens onto the focussing screen to be viewed through the eyepiece and having means for adjusting the value of at least one exposure factor, the combination comprising a pair of spaced polarizing plates having their respective axes angularly disposed relative to each other, said pair of plates being in the path of light rays reflected by the viewing mirror, exposure indicia provided on one of said plates, a member of rotatable polarizing characteristics movable in a path between said polarizing plates, and means for positioning said member by said adjusting means to provide illuminated indicia of the exposure factor value set by the adjusting means, the focussing screen being formed with a step portion along one side thereof, at least one of said polarizing plates overlaying said step portion, said one plate being provided with said exposure indicia, and said member being movable between said polarizing plates along the path determined by said one plate, the means for positioning said member includes a spring biased barrel and a reel disposed on opposite sides of the focussing screen and adjacent to the step portion formed thereon, a thread secured at its ends to said barrel and said reel, said member being secured to said thread, and a gear arrangement for rotating said reel by the adjusting means for moving said member by said thread; a frame having an aperture for the field of view, the frame overlapping the focussing screen and further formed with an elongated window above the step portion in the focussing screen and said polarizing plates, the indicia provided on one of said plates being viewable through said window, and an auxiliary reflector provided at a position outside the light path between the viewing mirror and the screen, the auxiliary reflector having a reflecting surface inclined to direct the light rays passing through the camera lens substantially from the central portion of the exit pupil of the camera lens to the window.