This is a Computer Serial Control Cable for DSLR Canon 300D/10D (DSLR Focus) diagram, depending on your electronics skills, these designs are perhaps only marginally more difficult than the basic circuits above, but provide a higher degree of protection by electrically isolating the camera from the computer. As a bonus they can also incorporate LED based status indication of the current state of the shutter control signal – which is very helpful in troubleshooting any serial port/software connectivity issues.
After the original basic circuit design was in use, Bill Drummond and Doc G suggested an alternative opto-isolator that would be a better way to drive this sort of circuit. A simple reed relay could also be used in a similar fashion. Bill proposed a draft circuit using an opto-isolator, which was then brought into reality with Matthew Chang’s circuit design and implementation. This was based on Bill’s draft design but used an alternative but compatible member of the 4N2x-3x opto-isolator family. It also added a couple of LEDs to show the current shutter state. Pictures of Matthew’s circuit inside the D9 shell and the finished article (only one LED actually fitted due to space limitations). Wade Calvert then tweaked Matthew’s design to use a single bi-colour LED to help fit the entire opto-isolated circuit into the confines of a D9 serial clamshell.
S: www.beskeen.com/projects/dslr_serial/dslr_serial.shtml
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