Refer this site
http://www.covingtoninnovations.com/...onRelease.html
build the serial port cable release get a serial to USB adapter cable such as
http://www.mittoni.com.au/usb-to-ser...er-p-1564.html
load drivers
match port from device driver to port in DSLR Focus
set camera to "M" and exposure length to "BulB" by using the toggle wheel
make sure DSLR Focus set to capture not focus which I'm sure you are aware of
always worked for me no problems