Patent GB-1217419-A (GB)
Title: Instructional optical kit
Inventor: NEHMANN EUCHAR
IPC: G09B23/22
Filed: 1968-08-13
Abstract: 1,217,419. Kits of optical parts; reflex cameras. E. NEHMANN [trading as FRANCKH' SCHE VERLAGSHAND-LUNG W. KELLER & CO.] Aug.13, 1968 [Feb.9, 1968], No.38663/68. Heading G2A and G2J. An instructional kit of optical components comprises lenses, diaphragms, mounts and tubular members for holding the lenses and diaphragms, the tubular members being connectable to one another end to end, the lenses, diaphragm and mounts being held in axial alignment, at least a part of the tubular members having conical end faces adapted to be releasably inserted into corresponding openings in optical housing ports, one of the housing ports being a camera casing of the single-lens reflex type, the components being adapted to form a readily dismountable and fully operative optical instrument, e.g. a single lens reflex camera, telescopic, projected, microscope, transparency, viewer. The kit comprises, for example, five lenses, two concave and three convex of which the concave lenses are of different size and power and each can be mated with a convex lens of similar physical size to form an achromat having a power different from either single lens of the combination. The lenses have flat rims which engage in slots in the inner surface of a split mount 11. The mounts can be held in tubular holders 17 which have one end formed as a tapered collar, the innermost end of which is stepped out from the tubular member, the internal diameter of the collar being the same as that of the external diameter of the tube. Thus a series of such members can be fixed together by inserting the free end of the tube into the collar of another. These tubes, the mounts or merely the lenses may be mounted in alternative holders. These holders 22 are also split in two halves and are made with a plurality of internal recesses 27, 29 for location of lenses and diapragms. One end of the holder 22 tapers inwardly and is externally formed with a flange, whereas the opposite end has an internal groove 34 and flange 35 which will sealingly engage with the tapered end of a similar holder. The holder 22 also has an internal helical groove 31 which may cooperate with a pin on an internal member to allow relative axial movement of such members to provide a focusing means. An example of a telescope is illustrated in Fig.6. Two tubular members 17 are mounted end to end, the tapered collar 19 of one locating in a complementary opening in a connecting member 36. The holder adjacent the member 36 houses three mounts 48-50 holding a predetermined combination of diaphragm and lenses. The other tubular member 17 houses lenses 55, 54 which cause an image to be erected. The connecting member 36 also has a series of internal grooves axial with the opening in to which tube 17 locates. Into these grooves is fitted a tube 41 housing a diaphragm 47 itself located inside a split holder 22, a pin 42 on tube 41 engaging in helical groove 31 of holder 22. The tapered end 32 of holder 22 houses a concaveconvex object lens combination and is located in a lens cap 44. The connecting member 36 also has  an externally screw-threaded portion 37 which can be fitted into the lens barrel 64 of the camera 61 and also has a threaded recess for connection to a tripod. To form a single-lens reflex camera a casing 62 has a lens barrel 64 having an internal screw thread adapted to receive an objective lens mount 66. This mount 66 houses an appropriate combination of the lenses provided with the kit. The camera has a mirror carrier 75 and a shutter 76 both mounted for rotation about a pivot 79. The mirror carrier has an extending arcuate portion 84 having a rectangular opening overlying a similar portion 89 of the shutter which has a slit 91 when in the inoperative position. In such position the mirror carrier is linked to the shutter by a catch 95 and is biased towards the shutter by a weak connecting spring. The shutter is connected to one end of a stray spring 82 connected to the casing. A release plunger 65 when depressed moves a lever 88 attached to carrier 75 downwardly raising both carrier 75 and shutter 76 into "wind-up" position. At the end of the travel the catch 95 strikes a projecting surface 104 and disengages the shutter from the mirror carrier, the shutter then being returned to its inoperative position by spring 82, and as its slit 91 passes the rectangular opening 85 in the mirror carrier it exposes the film in the camera. Release button 65 allows the mirror carrier to return and reengage with the shutter, If desired the objective mount 66 may be replaced by the objective portion of a telescope, viz the connector 36, tubular holder 22 and objective of Fig.6. The camera casing may also be used as a microscope stand.