All EOS cameras except the Canon EOS 400D/Digital Rebel XTi, Canon EOS 450D/Rebel XSi and Canon EOS 1000D/Rebel XS have a proprietary three-pin remote release socket shown below. The 400D, 450D and 1000D use a simpler standard 2.5mm jackplug with three connections and works in exactly the same way.
Remote release switches and cables can be bought as accessories from Canon or more cheaply from eBay.
The remote release switch has two positions similar to the camera's shutter release button. Half-pressure on the release switch activates the camera's auto-focus by connecting the "Ground" and "Activate AF" pins together. Full pressure on the release switch releases the camera's shutter by connecting the "Ground" and "Release Shutter" pins together. It isn't necessary to activate the auto-focus in order to release the shutter and a picture can be taken by only connecting the "Ground" and "Release Shutter" pins together. Activating the auto-focus releasing the shutter puts the camera into a heightened state of readiness and will reduce the variations between cameras.
Canon EOS 30D connectors (remote release socket is bottom left)
Remote release socket for Canon EOS 30D/40D/50D/5D Mark II/1D Mark III/1D Mark IV/1Ds Mark III showing pinout
Canon EOS 400D/Digital Rebel XTi, 450D/Digital Rebel XSi, Canon EOS 500D/Rebel T1i and 1000D/Rebel XS Remote Release Connector
Canon EOS 400D/Digital Rebel XTi, 1000D/Rebel XS and 450D/Digital Rebel XSi Connectors
(middle socket is the remote release socket)
2.5mm 3-connection Jackplug for Canon EOS 400D/Digital Rebel XTi, 450D/Rebel XSi, 500D/Rebel T1i and 1000D/Rebel XS remote release
Triggering the cameras from a PC
The simplest way to trigger the cameras from a PC is to use a USB controlled relay such as this low cost bus-powered 8-channel USB relay: USB-RLY08
National Control Devices LLC have a wide selection of more sophisticated PC controlled relays including 16-channel devices and USB, ethernet or wireless communications. Programming these devices is usually very simple and generally involves sending commands to open and close the relays to a virtual COM port. You will need to write your own software but any competent programmer should be able to do this. Mechanical relays are cheap and easy to use but will only be accurate to within a few 1/100ths second. More accurate synchronisation can be achieved by using solid state relays, trasnistors or opto isolators.
A typical setup to control and trigger 16 Canon EOS cameras from a single PC with 2 spare USB ports would consist of:
- A PC or laptop running Windows XP and our DSLR Remote Pro Multi-Camera software
- A 4 port USB hub connected to one USB port on the PC with a further four 4 port USB hubs connected to each of its ports. The USB cables from the cameras plug directly into the USB ports on the USB hubs. The USB hubs should be externally powered for maximum reliability.
- A 16-channel USB controlled relay plugged into the second USB port on the PC. The relays are then connected to the remote release sockets of the cameras.
- Software to control the relays and fire the cameras
Please note: The maximum USB cable length allowed by the USB standard is 5m (approx 16 feet). This can be extended by using USB hubs but you are only allowed a maximum of 3 hubs daisy chained together (giving a maximum cable length of 20m). You can buy active USB cables which can be daisy chained together but please be aware that these are really cables with a self-powered USB hub on the end. Self-powered USB hubs draw power from the USB interface instead of using an external power supply and tend to be less reliable than externally powered hubs.
In operation DSLR Remote Pro Multi-Camera is used to control the camera settings and manage the downloading and naming of the images and the USB relay is used to trigger the camera.
