remote shutter release - by opto-electronics

by opto-electronics It is true, of course, that it has been possible for many years to release a camera shutter remotely. But that is normally done by a (too) short cable, which can be a nuisance, and which is invariably too expensive for what it does. It seems therefore a good idea to release the shutter optically: the only prerequisite for this is that the camera is provided with an electronic shutter-release facility. The proposed circuit (see figure 1) is built into a small case (see figure 2) which is fitted with a flash connector enabling it to be fixed to the camera instead of the flash unit. The little case may be made from the screen- ing can of an r.f. or i.f. transformer. The simple circuit is based on a type CA 3140 opamp which has been con- nected as a differentiator. To drive transistor T1, the inverting input of the CA 3140 must be fed with a short negative pulse. This is here obtained from quick changes in the light in- cidence onto either of the light- dependent r...