I’ve built a remote shutter switch for my Canon 50D to enable it to take exposures longer than 30 seconds, which is essential in astrophotography. Since the camera already has a battery grip, I just bypassed the battery grip’s shutter button and put an external switch. To make it removable, I used a wire that plugs into a socket hidden neatly in the battery compartment.
Related link: View all home-brewed DIY astronomy equipment
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines