I need to turn a knob... Stepper motor?

I'm trying to remotely turn on a Canon Powershot S5 camera. It has a power knob that you turn about 15 degrees and then it snaps back to center. Here's a picture:


Note that knob at the bottom right, with the "off" button inside of it. I'd like to simply turn that knob.

I was thinking a stepper motor glued to the top of the knob?

That's kind of a shot in the dark though, I have no experience with stepper motors. If I went that route, would I then use something like this to drive it?


And any tips on which motor to use?

Or maybe I'm barking up the wrong tree?

Thanks for any help.

Servo - simpler and cheaper.

Interesting. Can I make a servo motor turn both ways? After it turns that dial, it needs to then turn it back the other way.

I have a servo motor, but it only has 3 wires, which as I understand it is two power leads and one signal lead.

Looking here for example:


The rotary solenoid sounds perfect.

I would use a rubber hose or a rubber foot (the kind with a hole in the middle for the screw) to "grab" the camera knob.

Interesting. Could you elaborate on this? I've been worried about damaging the knob through excessive force, and this sounds like a good solution.

As far as the camera being controllable via USB, this camera's predecessor, the S3, turns on when it receives 5v through the USB port. Alas, for whatever reason, the S5 doesn't do that, but I need to use the S5 because only it has a flash hotshoe.

Thanks for the excellent tips.

I'd go one step further on Richard's thought; use a servo with a straight horn (and maybe something to extend it), at the end of which you put some kind of rubber tip. Position the servo so that it "thumbs" the little projection of the knob left and right. This "thumb" lever should have enough give so that it acts like a user's thumb and doesn't rotate the knob more than necessary. You could then set up a second servo to "thumb" the off button, too...

How many degrees of rotation do you require on the camera knob? The typical servo max rotation is ~180 deg.