Highspeed photography 101 – Lesson 5

Highspeed Photography 101

Table of contents

Introduction
Lesson 1: Freeze the motion with your shutter
Lesson 2: Freeze the motion with your shutter II
Lesson 3: Freeze the motion with your flash
Lesson 4: A small but powerful helper: Arduino
Lesson 5: Trigger your camera with an Arduino
Lesson 6: Trigger your flash with an Arduino
Lesson 7: Working with sensors: Light barrier
Lesson 8: Working with sensors: Sound trigger

Lesson 5: Trigger your camera with an Arduino

Introduction
In the last lesson I showed what an Arduino is. In this lesson I’ll show you how to use an Arduino to trigger your camera.

Highspeed 101 - Splash in a glass

Equipment
– Camera
– Flash
– Remote trigger for flash (optional)
– Arduino
– Solderless breadboard
– Wires
– 1 100 Ohm resistor
– 1 SCR

Idea
If you want an image of a glass in the moment of filling, you need two persons. One will fill the glass, the other one will trigger the camera. But if nobody is around to help, you can use your Arduino to trigger the cam.
I planned to do a sequence and choosing the best picture afterwards. I wanted to freeze the motion with the flash, therefore I was shooting in a dark room. (See Lesson 3: Freeze the motion with your flash)

Camera settings
I used my camera in ‘burst’ mode. The shutter speed was set to 1/125s because I didn’t want to use HSS flashes. On the other hand I don’t want a longer shutter speed, because I was doing a sequence. Aperture was set to 8, to get a bigger DOF. As my light tests were to dark, I had to change the ISO to 400. The cam will trigger the flashes with the remote trigger. (If you don’t own a remote trigger, you can use master/slave flash or a sync cord).

Flash settings
I used two SB28 flashes in ‘repeating flash’ mode. My tests showed that the flash will trigger about 10 times (at 1/32 power, about 5 fps) without any significant loss of brightness. These were ideal settings for my sequence.

Arduino
To trigger the camera with the Arduino I used a self made camera remote. The remote slot on my sony cam has three pins, if you shortcut pin 1 and 2 the cam will focus, if you shortcut all pins, the cam will trigger. (DIY remote camera trigger: Sony, Canon, Nikon). I used an old CD-Audio cable to build the trigger. If you shortcut pin 1 and 2 the cam will focus and no input can be made, therefore I added a switch between the wires from pin 1 and 2.

Self made remote trigger

Next to the trigger is the breadboard. On the breadboard I mounted a SCR (silicon controlled rectifier); a SCR is electronic component that shortcuts the anode and cathode as soon as there is a signal on the gate. The middle pin (gate) will be connected to an digital output of the Arduino, the anode to the positive connection of the remote trigger and the cathode with the cable which comes from the focus trigger. How to find the anode and cathode on the SCR should be written in the data sheet. (If your using Hiviz.com parts see Delay unit manual Step3). Finally we connect the GND from the Arduino with the cathode of the SCR.

Arduino and breadboard

The Arduino was setup to sleep 10 seconds, then trigger the camera for 3 seconds.

int SCRPin =  8;    // SCR connected to digital pin 8
int done = 0;       // done flag

void setup()   {
 // initialize the digital pin as an output:
 pinMode(SCRPin, OUTPUT);
}

void loop()
{
 if(done == 0){
 done = 1;                     // set done flag
 delay(10000);                 // wait for 10 seconds
 digitalWrite(SCRPin, HIGH);   // set the SCR on
 delay(3000);                  // wait for 3 seconds
 digitalWrite(SCRPin, LOW);    // set the SCR off
 }
}

Finally the setup:

Setup

Taking the picture
If everything is prepared, taking the pictures is a easy. Press the reset button on the arduino, wait and as soon as the first flash appeared I started to fill the glass.

Conclusion
In this lesson I showed how easy it is to trigger a camera with an Arduino.