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Remotely triggered photography Electric Camera Shutter Release By Julian Edgar Triggering a camera remotely allows you to take photos that might otherwise not be possible: dangerous locations or situations, wildlife photography and so on. You could also generally improve your photographic creativity. But how do you press the shutter release from a distance? O NCE, ALL CAMERAS had a female cable release thread in the shutter release button, allowing the use of a long (often pneumatic, sometimes electric) cable release to let you to trigger the camera from afar. But these days, plenty of cameras (most?) don’t have this facility. In some cases, you can buy a dedicated electric cord that plugs into the camera – but you’ll certainly have to pay big dollars for it. Remotely triggering a camera – any camera – is a problem no longer! What we have here is a simple and cheap DIY project that will allow any camera to be fired from a good distance. With a little ingenuity it could even be adapted for radio control. The camera doesn’t have to be fitted with a threaded shutter release button and it doesn’t need a socket for an electrical cable release. In fact, all that it really needs to have is a tripod mount (we haven’t found a “real” camera yet that doesn’t!) and a button that gets pressed to take the picture (ditto!). It uses a small solenoid – a device which consists of 66  Silicon Chip www.siliconchip.com.au a coil usually wound around some form of armature or plunger. When the coil is energised by current, the armature moves due to the magnetic attraction (or repulsion) of the coil. It is this movement which is used to push the camera release button. The design The solenoid is mounted so that its extended plunger pushes the camera shutter release button. A mount for the solenoid – folded from aluminium sheet – is attached securely to the camera via a screw into the tripod socket. The solenoid is fired by the use of a pushbutton switch mounted on a remote handpiece which also contains one or two batteries. The solenoid used here was salvaged from an electric typewriter. Pretty well any small solenoid can be used – so long as it has an adequate amount of ‘push’ and can be operated at low voltage. The handpiece was made from an old personal deodorant container, while the pushbutton, battery clips and cable were bought specifically for the project. But you might even have these in your junk box! So depending on how you source the parts, this device shouldn’t cost much at all. out and then cut to shape using an electric jigsaw. The sheet is 2.5mm in thickness – strong enough to have the required stiffness but still light and easy to cut and bend. Note that offcuts of sheet aluminium are available from non-ferrous scrap metal dealers very cheaply. They’ll cost a lot more if you go to a specialist aluminium supplier! The piece of aluminium was then bent to the right shape in a vice and the holes for the solenoid and tripod mount drilled. The mount was painted black, and a short ¼ -inch screw used to attach it firm- Building it 1. The Bracket The typewriter solenoid selected for this project normally pushes the daisywheel letter against the ribbon and paper. To facilitate this, the plunger of the solenoid has a groove machined in its end. This results in a sharp edge – not really what you want striking your camera’s shutter release button! To get rid of these sharp edges the solenoid was disassembled and the plunger end smoothed with a file. Once that was done, a piece of cardboard was cut out and formed into a template for the bracket. This bracket needs to place the solenoid at the right angle and position so that as the plunger extends, the shutter release button is depressed. to join the solenoid to the handpiece, as shown below. ly to the camera tripod mount. This shows how the solenoid is positioned so that its plunger is at the right angle to push on the shutter release button. A long cable is used 2. The Handpiece How you make the handpiece depends a little on the amount of “juice” you need to actuate the solenoid. This can be best found out by actually triggering the In the case of this Nikon F60 SLR, this required an ‘L’-shaped bracket which was then folded into the right shape – see photos. With the shape organised, a piece of scrap aluminium sheet was marked www.siliconchip.com.au April 2003  67 solenoid when it’s in place on the bracket. When operated on the bench, a solenoid may work perfectly well on 9V (or lower), but with the voltage drop of a long cable and the effort of having to push the camera’s shutter release button, more voltage might be needed. I found this out the hard way: the typewriter solenoid bench-tested fine on 9V, so I built this small hand controller using a commercially available box and a single 9V battery. But this system simply didn’t have enough power to trip the camera! Time for a rethink. Because the power is applied in such a short burst (you should never leave you finger resting on the button), much higher voltages than the normal working voltage of the solenoid can be used without problems. In my case, I simply used two 9V batteries in series, giving 18V output. That triggered the solenoid decisively and hard! The new handpiece was made from a deodorant container – emptied of course! The two 9V batteries – complete with their battery clips – fitted into it very nicely, while the pushbutton switch was placed through a hole drilled in the cap. Making a battery change is as easy as lifting off the cap and sliding the old batteries out but they should last for ages, depending how much you use the remote trigger. Using it It makes things a lot easier if the camera that you are using has an inbuilt motorised wind-on. But other than that, just about any camera can be used. The camera should be pre-focused – and the auto focus disabled if possible – and in some cameras the viewfinder should be blocked (eg, using a rubber cap) to prevent extraneous light from causing metering problems. Then it’s simply a case of setting up the camera (you should still be able to use a tripod if required, with the tripod threaded fitting long enough to go through the alloy plate), standing back and pressing the handpiece button at the right moment. The circuit could hardly be simpler – that’s the beauty of this project. Whether you need one 9V battery or two depends on both the solenoid and the cable length. digital cameras require a significantly longer “firing” time than conventional cameras – the best are about 100-200ms, while many of the “happy snap” (ie, cheaper) variety require half a second or so. Therefore, you will need to experiment with the release to determine just how long you need to hold the button down to get your picture. The earlier comments about turning off auto focus, etc, still apply – that is, if you can manually focus the camera. Some simply don’t let you! Also note that apart from some cheap digital cameras, most are capable of being remotely controlled via their bus. However, the chances of finding a remote control cable in your new camera box are pretty slim and the earlier comments about the cost of special cables certainly applies to digital cameras – if not dramatically more so! This project is definitely a cheaper alternative, especially SC if you can scrounge the parts! Radio Control We mentioned earlier that this project could be adapted to radio control with a bit of ingenuity. In fact, it’s not rocket science: just about any of the remote controls we have recently published could be used. All that is required is to wire the output device of the remote control receiver, whether that be a relay or a switching transistor, in place of the pushbutton switch (as shown below).You may well find that the battery required to power the radio receiver can also power the solenoid. The radio control must be set for momentary (as distinct from alternate) action. It needs to actuate when you press the button and let go when you let go the button. (Alternate action requires two pushes of the button to actuate and then let go). One point to note: the solenoid, being a coil, generates a significant back-EMF when the power is removed. This won’t worry either a pushbutton or a relay contact but could be disastrous for a switching transistor. If unsure, place a reverse-biased small power diode (1N4001 etc) across the solenoid coil, with its cathode (the banded end) towards the positive supply. Digital cameras This project is just as suitable for use on a digital camera, with one important proviso: most 68  Silicon Chip www.siliconchip.com.au