In the process of building two intervalometers (analog, Arduino powered), I learned how easy it is to construct a remote trigger for a DSLR’s focus and shutter controls. Both of those units featured manual controls for focusing and taking photos, but I wanted to build another separate project that would only feature that ability. This would allow the device to be much smaller and lighter.
For this build I used a 3″x2″x1″ RadioShack project box, a 3.5mm stereo socket, and two momentary pushbuttons. In accordance with how my Canon Rebel XSi works, I wired the shutter trigger (red pushbutton) to the tip of the socket and the focus trigger (black pushbutton) to the middle contact. Then I wired the other side of both switches to the shield of the socket. I am a big fan of using a socket for a project such as this since I can now use a cable of any length or configuration as long as it has a 3.5mm plug on the end that plugs into the box. This is an incredibly simple build that works great and should come in very handy for all my remote triggering needs.