Electronic Shutter Release

In 1984 I made a camera trigger to capture transient phenomena. I had a Mamiya ZE 35mm camera and Mamiyalite ZE flash unit. Typical for bodies of its time, the only means of remotely triggering the camera was the cable release socket built into its shutter release button. This was meant to be used with a purely mechanical cable; it let you operate the shutter release from a small distance away, and in a manner that avoided introducing vibration to the camera at the moment a picture was taken.

My solution for releasing the shutter electrically was to make a solenoid trigger. I rewound the coil of a small solenoid so that it would produce the necessary force when operated at 9V. It was a retraction type solenoid, meaning that applying current to it pulled the armature in. I wanted an extension solenoid, so I drilled a hole in the rear of it. I removed the camera end from a cable release - the part that screws into the cable release hole - and soldered it to the rear. I drilled a hole in the end of the armature, cut the pusher end off of the cable that was part of the release, soldered that into the armature, and then fed the pusher down through the solenoid and out the end of the cable release.

The whole thing was light enough that I could simply screw it onto the shutter release of the camera and it would be supported without depressing the button. The other end of the solenoid was threaded for mounting in the way it was originally designed for. I found a cap that would fit this thread. This turned out to be particularly useful, because if set for automatic exposure, the camera required that the shutter release be partially depressed for long enough for it to do its calculation. If the shutter release was simply slammed down as fast as the solenoid did it, the shutter was released instantly and with incorrect exposure. By adjusting how far I screwed the cap down I could make the shutter release be initially depressed far enough to activate the camera.

To operate the solenoid I made a circuit that would briefly apply current to it when triggered. It also had a “test” position that would operate a sounder instead of the solenoid, to facilitate setup. I ended up using this system mainly for taking pictures of rockets lifting off.

The devices that I used with the trigger included hardwired circuits and an ultrasonic remote. The ultrasonic remote is at left. I made it with a pair of surplus 40 kHz transducers. The green extension cord at right has an inline switch to set whether devices plugged into the mini jack on the end operate as normally-closed or normally-open triggers. The device with the bolt was used to take the tennis-ball cannon pictures below. No, I don't yet have any of the other (more successful) pictures I took with this system scanned!

Anthony firing TBC Mike firing TBC

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