EOS Shutter Cables

The shutter cables are additional PC operated devices.  They are needed for Canon EOS cameras with Digic 3 processor in order use mirror lock feature. For Digic 2 camera such cable is need to make both -  to use mirror lock feature and to control the shutter.
There are three main types of shutter cables and they are supported by APT:
Shoestring Astronomy DSUSB/DSUSB2
Shoestring Astronomy DSUSB/DSUSB2 long exposure shutter controller. Once a DSUSB or DSUSB2 option is selected from the “Long exposure control” list, APT will try to make a connection to the controller. More information about DSUSB/DSUSB2 can be found on http://store.shoestringastronomy.com/products_ds.htm
Serial Cable
Serial control cable (RS232) connected to COM port or to USB (with appropriate Serial to USB converter). If you don't want to make such cable yourself, here is list of some vendors.
Pierro-Astroit includes RS232 to USB converter. http://www.pierro-astro.com/ControleAPN.html#1
Hap Griffin Astro-Cables - http://www.hapg.org/astrocables.htm
Two links (of course there are more in The Net) with "Do-It-Yourself" instructions:
Biula Audio trigger
Biula Audio trigger uses the audio port and special cable control the camera shutter. Instructions how to build this cable can be found here: http://www.ideiki.com/astro/biula_audio_trigger.pdf
Note - make sure that the audio volume is set to maximum!