Noob trying to trigger camera shutter w/ Nano

Hi,

I am new to Arduino and for my first project I'm trying to built a camera control system (1 servo for panning + camera shutter trigger).
I've got the servo part working but I can't trigger the camera (Canon 400D) shutter. I think there's something wrong with the way I built the circuit.
I would appreciate any help you can give me.

Got it working, the problem was not the circuit, it was a cheap chinese 2.5mm male to male cable, used a different cable and it's working fine.

I connect the Arduino pin directly to a Canon shutter with or without a resistor for safety.

thanks, I was going to ask same kind of question, and your graph perfectly answered it.
(going to use arduino for driving a Canon 1000D and was wondering how to cable a transistor for that, etc ...)