i am trying to control my nikon d3100 with an Arduino board. I short circuited the focus and shutter and used a transistor to connect it to the arduino.
If I am controlling the opening time of the shutter on the camera the sketch works fine.
Now I am trying to set the shutter time in my sketch.
I am setting the camera on bulb mode. As soon i run the sketch the shutter opens, but does not close and when i unplug the caple the shutter closes.
Try adding a pull-down resistor on the Base of the transistor.
Otherwise, replace the transistors with Optocouplers, those are a better solution for a remote shutter. This way you won't destroy your camera if you mess something up.
I did put a 220 Ohm resistor and also a resistor between ground and the transistor.
It works just to trigger the camera with pre set speed (1/20 for example).
Maybe the camera is set to open at first push of the button, and then close at the next push ? Try giving it two pulses after each other. Another thing can be the order of the two signals that needs to be correct (1. Focus on - 2. Shutter on - 3. Shutter off - 4. Focus off)