Hobby Robotics

Update: Check out my latest Camera Axe project for a much more robust device that handles this.

This article explains how to use a microcontroller like Arduino to trigger the shutter on a Canon DSLR camera that has an N3 connector. Canon cameras like the 10d through the 40d and their professional cameras all have this connector. Many other DSLR cameras have a very similar connector that you could adapt this article to, but they’ll require a little more research from you.

This project would work well with another project I wrote about here. It describes how to trigger a flash with sound or a laser trigger. You could easily adapt it so it triggers your camera instead of the flash. Note that in that article I discuss the downside of directly triggering your camera (namely the delay), but if a delay of a fractional part of second doesn’t matter then triggering your camera directly works great. Some cool applications would be having your camera take a picture every time you say a word, taking a picture every time someone rings your doorbell, or taking a picture when someone walks down the hallway.

The most difficult part of this tutorial is getting a cheap N3 connector. Canon decided to go with a proprietary plug and they charge ridiculous prices for any accessory that uses this plug. I think their cheapest device with the N3 plug is a basic remote trigger and they charge $50 for it. You could try to make your own plug. But my favorite solution was to type “canon n3 remote” into ebay and I found lots of simple remote triggers for under $10. I just got my plug from one of these devices.

With the plug in hand I started figuring out what the different wires did. Here is picture of the the plug and the color of wire attached to each pin in the plug. The white wire is ground. The green wire is +3V and when it’s grounded it causes the camera to focus (similar to pushing your shutter button half way down). The red wire is +4V and when it’s grounded it causes the camera to take a picture (depending on the mode the camera is in it might focus first). If you want to guarantee a quick picture you should pre-focus your camera and then set focus to manual.

Now that we know how the N3 plug works all we needed to do is wire a circuit that lets us switch the green (focus) or red wire (shutter) to ground. I actually find the focus wire to be pretty useless since I can have the camera focus before it takes a picture if I want, but there are some use cases where it would be nice so I’ve included it here for completeness. I figured a simple switching transistor like the 2N2222 would be be the perfect switch for this project and so that’s what I used. See my circuit diagram below.

This example code for Arduino is very simple. All it does is focus when you hit the “f” key and and take a picture when you press the space bar key. Here is a link to the code.

// Maurice Ribble
// 4-28-2008
// http://www.glacialwanderer.com/hobbyrobotics

// This code just tests my camera trigger.  It lets you
// focus the camera by pressing the 'f' key and take a
// picture by pressing the space bar.

#define FOCUS_PIN 6
#define SHUTTER_PIN 7

void setup()
{
  pinMode(FOCUS_PIN, OUTPUT);
  pinMode(SHUTTER_PIN, OUTPUT);
  digitalWrite(FOCUS_PIN, LOW);
  digitalWrite(SHUTTER_PIN, LOW);
  Serial.begin(9600); // open serial
  Serial.println("Press 'f' to focus and 'spacebar' to trigger shutter");
}

void loop()
{
  int cmd;

  while (Serial.available() > 0)
  {
    cmd = Serial.read();

    switch (cmd)
    {
    case 'f':
      {
        digitalWrite(FOCUS_PIN, HIGH);
        delay(800); // May want to adjust this depending on focus time
        digitalWrite(FOCUS_PIN, LOW);
        break;
      }
    case ' ':
      {
        digitalWrite(SHUTTER_PIN, HIGH);
        delay(2000); // May want to adjust this depending on shot type
        digitalWrite(SHUTTER_PIN, LOW);
        break;
      }
    default:
      {
        Serial.println("Press 'f' to focus and 'spacebar' to trigger shutter");
      }
    }
  }
}