Arduino Canon Hack control

Hi everybody Im new with Arduino and I dont remeber too much about programming. Im a scuba diver and a photographer and Id like to build my personal underwave photo huosing. Id found something interesting about the DIY housing but I need some help about programming the Arduino. Could someone tell me which are the basic command to open a session with a Canon Eos and change Mode (M,Av,Tv,P,A), speed, shutter, iso and exposure compensation? Regards


What EOS do you have?

I have a Canon 20D and a Canon 550