GB710978A - Improvements relating to photographic lens shutters - Google Patents

Abstract

710,978. Photographic shutters with built-in flashlamp synchronizers. DECKEL, H., and DECKEL, F. W. Feb. 4, 1952 [April 10, 1951], No. 2898/52. Class 98(1) In a photographic shutter having one or more groups of flashlamp contacts, the or at least one group of which is settable to close the flashlamp circuit at a variable predetermined time prior to the release of the shutter to compensate for the lamp lag, a member mounted in the shutter casing and having a timing cam disc with several timing faces acts on the setting element of the settable contact and is connected with the exposure time setting element of the shutter to move simultaneously therewith, said connection being disengageable to permit relative adjustment between the cam disc and the exposure time setting element so that the contacts are adjustable with a number of selectable ranges by setting the shutter exposure time. As shown, the shutter is provided with two sets of flashlamp contacts. One set for lamps of finite lag comprises an adjustable stationary contact lever 28 and a movable contact pin 32 on a spring driven tripping member 34 for the lever holding the shutter tensioned, the driving spring for the member 34 being tensioned by the shuttertensioning member 12. The other set for instantaneous lamps comprises a projection 72 on the shutter tensioning member and a stationary contact 68 which is held clear of the path of the projection 72 against an insulated block 70 when lamps of finite lag are used by an insulated arm 66 of a lever pivoted at 58 and engaging a ring 48 set according to the lamp used against one of four marks (not shown) on the exposure time setting ring 16, three F, M, S, for different lag lamps and one X for instantaneous lamps. To ensure accurate synchronization of the flash with the shutter opening so that the available illumination is fully utilized, the adjustment of the contact lever 28 depends not only on the choice of lamp but also on the exposure time and the ring 44 fixed to the ring 48 and bearing the adjusting cam 42 having faces f, m, s, x is connected to the time setting ring 16 by spring detents on the ring 16 engaging in recesses in the ring 48. When this ring is set for instantaneous lamps, the lever 28 is engaged by a portion x of the cam so that it is held clear of the contact pin 32 until after the closure of contacts 68, 72, the lever arm 62 then being engaged in a recess in the ring 48 so that the contact is freed to lie in the path of the setting ring projection 72. Specifications 661,869 and 686,136 are referred to.