Patent GB-736611-A (GB)
Title: Improvements in stereoscopic photographic cameras
Inventor: SMITH GORDON N
IPC: G03B35/10
Filed: 1952-12-15
Abstract: 736,611. Stereoscopic roll film photographic cameras. SAWYER'S, Inc. Dec. 15, 1952, No. 31770/52. Classes 97 (1), 98 (1) and 98 (2). The camera comprises a frame structure and a pair of laterally-spaced optical exposure systems arranged to make simultaneous exposures on photographically-sensitive material and each comprising an exposure-framing opening at its rearward end and an objective towards its forward end, the objectives lying in a common plane and means being provided for maintaining the sensitive material adjacent the rearward ends of the systems in the common focal plane, and the exposure systems are vertically movable within the frame structure. As shown, a twin objective stereo roll film camera is provided with two exposure apertures 110 in a fixed film guide and across each aperture is movable simultaneously a light tunnel 111 bearing at the forward end an objective and an adjustable diaphragm 115 to define exposure areas on either the upper or lower half of a film which is fed in either direction between a supply spool 23 and a take-up spool 26 by a sprocket 35, the shaft of which carries a gear 39 geared by idlers 40, 41 to gears 42, 54 on the spools shafts, friction clutches 44, 46 and 56, 57 being provided between the spools and the gear driven spool shafts to take-up slack film and avoid excessive film tension. Spring mounted dogs 52, 59 engaging gears 42, 54 driving the spool shafts through these clutches prevent gearing backlash. The 16- tooth sprocket effects a feed stop for a 35 mm. film for each half revolution, each exposure occupying an area 16 mm. square and being separated from its stereoscopic pair member by two exposure spaces, and one series of exposures is taken on one longitudinal half of the film and the film is then moved in the opposite direction to expose the other half as shown in Fig. 26, so that unexposed areas are left between the first and second and between the two right eye views and between the left eye views at the inner end of each row. The right and left eye pictures are identified by dissimilar lateral extensions produced by notches 325, 326 in the adjacent margins of the light tunnels 111. When the supply cassette is properly located in the supply chamber 13 a red mark on a pivoted plate engaged by the spool becomes visible through a hole in the bottom of the camera. The knob 128 is moved clockwise to the position shown in Fig. 1. As a result, an eccentric pin 131 thereon engaged in a slot in a yoke 133 follows a semi-circular path bearing against a cam-plate 138 so that the yoke and with it vertically slidable carriages 112, having pins 135 engaged by the yoke and supported on posts 120, 122 and 124, 127 and carrying the objectives and light tunnels 111, are moved into their lowermost positions, meshing sectors 136 pivoted at 137 and engaging the pins 135 engaged by the yoke ensuring equal movements of the carriages. Simultaneously a pinion 141 on the knob engages a rack 142 on a masking plate 144 to move this to the left of the camera as shown in full lines in Fig. 9 thereby bringing apertures 149 overlying the lower half of the film into register with the objectives, and also by a spring wire lever 106 engaging in a slot 152 on the plate 144 rotating a plate 101 into the full line position of Fig. 12. The film is held on the sprocket and against the flanges 116 at the ends of the light tunnels 111 by spring presser plates (Figs. 7, 8, not shown) mounted on a plate fixed to the camera back. To prevent entry of dirt into the camera the apertures in the front wall of the camera are closed by screw-in windows 108 having internal threads 109 for filter mounts. The film end having been passed from the supply spool through a slot 31 in the outer shell 26 of the takeup spool between which and the hub 27 rotatable on the manually rotatable shaft 29 the end is gripped, the hinged rear door of the camera is closed. The film winding knob 50 on the spool shaft 29 is then pulled outwardly disengaging the gear 43 on the shaft from the idler gear 40 and so freeing the knob from the spool which is rotated through the friction clutch 44, 46 by the gear 42 freely mounted on the shaft and driven from the idler gear 40. If a 36-exposure film is to be used the knob is rotated to bring the thirty-eighth scale mark opposite the stationary pointer 69 while if as shown a 20-exposure film is used the twenty-second scale mark is brought against the pointer 69. The shutter is released and the film wound on three times bringing either the thirty-fifth or as shown the nineteenth mark opposite the pointer 69. In the rest position of the camera after the trailing end has been wound off, the shutter is set as shown in Fig. 13 so that a block 83 on a shaft 84 and projecting through slots 72 in two slides 71 is in the full line position shown in Fig. 12 preventing movement of either of the slides 71 and thereby rotation of the gear 39 and hence of the film feeding sprocket 35. On now pressing the shutter trigger button 92 the release lever 90 moves clockwise against a return spring 93 about a pivot 87 and so rocks clockwise a coaxially mounted pawl 86, the nose 99 of which releases a main pawl 97 urged anticlockwise by a spring 88. A projection 193 on the pawl 197 then moves anticlockwise a pawl 190 releasing the shutter latch 185. This is brushed aside by the shutter plate 154 under the action of its spring 163, and this plate opens the apertures 167 in the plate 153 in register with those 149 in the mask plate 144 in front of objectives in their lower position. The latch 188 is released at a selected later instant to end the exposure by means of an escapement mechanism (Fig. 14, not shown) moved by a pin 96 on the pawl 97 which is driven by the spring 88 and governed by a cam 205 on a shaft 95 adjustable by a timesetting dial 209 (Fig. 2), a portion of the mechanism normally pivoting on the cam 205 to trip the latch. When the button 92 is depressed the release lever 86 is held in its clockwise-moved position by the pawl 97 blocking the return of the release lever nose 99, so that the eccentric 85 on the shaft 84 in line with the block 83 is held parallel to the camera front so that the slides 71 are free to move. Since the knob 128 has been positioned for an unwinding movement of the film from the supply cassette, the lug 103 on the plate 101 is positioned to allow movement of the upper slide 71 while preventing movement of the lower slide. The knob 50 is therefore rotated anti-clockwise so that the sprocket gear 39 is rotated in the same direction and hence one of the depending pegs 61 on the sprocket gear engages the upwardly projecting wing 80 of the upper slide and moves it to the right against a return spring until the peg 61 moves over the slide near the wing roots depressing the slide which is snapped up behind the peg by a return spring 75 (Fig. 11) into the normal position shown. Simultaneously a depending peg 184 on a cam 100 also on the sprocket shaft 38 moves a slidably mounted pawl 175 to the right (Fig. 13) whereby a lug 174 engaging tabs 172, 173 on the trailing rear and leading front shutter plates 153, 154, slidably mounted between shoulders on pegs 145, 146 moves the shutter plates to the right (Fig. 13) tensioning the driving springs 160, 163 respectively. The shutter plates 153, 154 are held set by a pivoted latch 185 engaging behind vertical edges 186, 187 respectively while the plate 153 is also held by a pivoted latch 188 engaging behind a vertical edge 189. The film is wound on by rotating the knob 50 anticlockwise (Fig. 6) and this sequence of shutter-release operation and film winding is repeated three times in all to present an unexposed, unfogged area behind each objective. Exposure counting is effected by the gears 42, 43 each having one tooth less than half the number on the idler gear 40. When the numeral 1 arrives at the pointer 69 it is no longer possible to unwind the film from the cassette due to engagement of a pointed nose on a plate 48 secured to the gear 43 on the shaft of the knob 50 clockwise of one of the pointed noses 67 on the plate 63 coaxial with the idler gear 40 which is then in the position shown in Fig. 6, the plate being held against the pins 64 on the gear 40 which rotates at only half the speed of the gear 43. By this means removal of the film end from the cassette is avoided. If the spool gears 42, 43 and hence also gear 54 make substantially a full revolution for each revolution of the gears 39, 40, 41, only a single nose 67 is required. The knob 128 is therefore then rotated anticlockwise to move the selector mask 144 and the lug 103 on the plate 101 to the dotted line positions shown in Figs. 9 and 12 respectively and to move the objectives into their upper position. The knob 50 can now only be rotated clockwise. Since it is necessary to wind the film in order to set the shutter, the first two spaces in the upper row are wasted as indicated in Fig. 26. Cycles of exposure and film wind then continue until the fogged leading strip comes opposite the objectives preventing further exposures but allowing the film to be wound into the cassette since, owing to the plate 48 now being able to move relatively to the pins 64 due to the slots 65, the winding knob does not become locked. A spring ring with a bend 70 forming a pointer is manually rotatable relatively to the knob 50 against friction so as to indicate the mark initially placed opposite the pointer 69 thereby indicating when rewinding is complete. The duration of the exposure and the lens aperture are set by means of a calculator mounted on top of the camera. This comprises a stationary plate 239 bearing a scale of " Subject Brightness " 401, fixed " Lens Opening " and " Shutter Speed " pointers 238, 210 co-operating respectively with scales on adjusting knobs 237, 209, and a fixed pointer 278 co-operating with a hyperfocal distance scale on the knob 237. A