shown in fig4 in which the raised portion 52 on its leading edge re engages with the cocking element 51 during movement of the actuator 62 the switch s 2 normally held closed is opened when switch s 2 is opened the exposure control circuit now shown begins to compute the proper exposure time by means of a photosensitive element associated with the exposure control circuit such as a photodiode 53 which is exposed to scene light simultaneously with the release of latch 46 and the opening of shutter blade 16 the lug 65 on the impact actuator 62 pivots into engagement with the unlatching leg 31 of the piezoelectric firing spring latch 15 thereby releasing the latch hook 29 from the firing spring 10 as shown in fig3 the firing spring 10 then rapidly moves the hammer 11 into engagement with the anvil 13 of the piezoelectric generator 17 to produce electrical energy for flash ignition if a flash array is present in the socket previously described a flash will be generated to illuminate the scene to be photographed after a time interval related to the scene light the exposure control circuit de energizes the electromagnet 101 thus releasing the armature 103 to allow the closing blade 18 to move under the influence of the spring 40 to cover the exposure aperture 24 cocking of the shutter is effected during return of the release member 56 to the position of fig1 under force of the spring 79 during such return motion the pin 58 opens the switch s 1 and the lug.