Supplementary objective with continuously variable magnification

1,054,972. Zoom lens attachments. K. VOCKENHUBER and RAIMUND HAUSER. Feb. 24, 1964 [Feb. 22, 1963], No. 7624/64. Heading G2J. In a variable-magnification attachment for a photographic objective in which positive lens L, and negative lens L 4 form a Galilean telescope system, and two lenses L 2 , L 3 of substantially the same refractive power but of opposite sign, the negative lens L 2 being nearer the front, are movable in opposite directions to vary the effective focal length of the system, one of the lenses L 3 has its axial movement a second or higher power functions of the axial movement of the other lens L 2 so that the image position remains constant during zooming movements. As shown, L 2 has a linear movement with respect to variation of focal length of the objective. As applied to an 8 mm. camera having a 12À5 mm. focal length main objective, the supplementary attachment forms an objective of continuously variable focal length ranging from 9 to 18 mm. The relative aperture may be 1:1:8. Optical data are given for the example shown.