Abstract: A mirror operating mechanism in a single-lens reflex camera using a small film cassette. The mirror operating mechanism has a main plate having two guide shafts in parallel with the optical axis of the photographing lens of the camera and provided in the space between the picture opening and the film winding chamber of the film cassette. A mirror lifting drive plate and a mirror lowering drive plate are slidable along the two guide shafts, respectively. Driving coil springs are provided in parallel with the two guide shafts for driving said mirror lifting drive plate and mirror lowering drive plate, respectively.

Abstract: Automatic exposure control is enhanced by providing a fixed diaphragm equivalent to the maximum aperture of the adjustable camera diaphragm so that the fixed diaphragm limits the maximum aperture to a consistent value. Consistent light measurements are possible as long as the lens being used does not interfere with the quantity of light entering the diaphragm.

Abstract: A simple mechanism is provided for winding film in a film cassette in which a pawl engages a perforation in each film frame to actuate a film stop device which, in turn, disengages the pawl from the perforation to remove any force from the film during picture taking. Winding force is transmitted from a unidirectionally rotating film feed disc to a reciprocating link and then to a undirectionally rotating spool gear which drives the film spool.

Abstract: The present invention is a film feed mechanism having a take-up shaft spaced apart from the film take-up spool. A bell crank is connected via a link to a conventional film feed control disc coupled to the take-up shaft. The reciprocal movement of the link is applied to the bell crank. The bell crank is provided with a first pawl and a second pawl. When the bell crank is moved to the right, the first pawl is in engagement with a first gear, which via second and third gears, causes the spool gear to be rotated counter-clockwise; however, the second pawl is slidingly disengaged from a rotating fourth gear. When the bell crank is moved to the left, the second pawl is in engagement with the fourth gear, which via a fifth, second and third gears cause the spool gear to be rotated counter-clockwise; however, the first pawl is slidingly disengaged from the rotating first gear.

Abstract: An electro-mechanical shutter release delay apparatus includes a front curtain lock lever 4 sharing a common pivot axis 6 with a release lever 5 and joined to the latter by a spring 7. The depression of a shutter release rod 8 initially rotates the release lever 5 to close a first switch S.sub.1 which energizes front and rear curtain holding magnets M.sub.1 and M.sub.2. Continued depression tensions the spring and eventually closes a second switch S.sub.2. The latter energizes a flood lamp and initiates a time delay circuit, whose output deenergizes the front curtain holding magnet. The spring then rotates the lock lever to release the front curtain and commence the exposure, by which time the lamp has reached maximum intensity. After the proper exposure time has elapsed the rear curtain holding magnet is deenergized to release the rear curtain and terminate the exposure.

Abstract: A miniature single lens reflex camera using cassette film is disclosed. The camera can be operated with inexpensive lenses not having large back focus, due to the addition of a glass block between the shutter and the film plane. The finder optical system is short in actual length due to the combination of a trapezoidal prism, a right angle prism, and an equilateral prism.

Abstract: A cassette type single lens reflex camera includes a longitudinally extending zoon lens system and a replacable film cassette disposed in opposite sides of the camera casing, the cassette having enlarged film storing opposite end sections joined by a tubular film guide with an inwardly vertically facing framing window. A 45.degree. semitransparent first mirror intercepts the zoom lens longitudinal optical axis to reflect lens traversing light through a rear lens group onto a second 45.degree. mirror mounted in the casing in the space between the cassette end sections and oriented to deflect the light from the first mirror to the cassette window. The light traversing the first mirror traverses, successively imaging and field lenses an erecting prism and an eyepiece lens which define a viewfinder.