DIY intervalometer for Aaton for under $40!

Nima Khazaei · July 21, 2015

So I just bought an Aaton XTR Prod, and wanted to try some time-lapse photography. I didn't particularly want to pay hundreds of dollars to buy or rent an intervalometer... so I'm working on building one myself. As it turns out, it's actually very simple!

Here's a video of the prototype I just got working on the bench. (excuse the awful cinematography :) https://vimeo.com/133953475

The core components are an Arduino ($25), which acts as the programmable brain, a Lemo2 connector ($10 on eBay—Lemo model FFA.0S.302) to hook it up to the camera, and a transistor and two resistors (see attached schematic for what they do).

All it does is simulate an occasional tap to the "test" switch, but I think this is what all the intervalometers do, beside the eShot. I could reliably get intervals as short as 1.05 seconds using this method. Any shorter, and the camera would start to miss the occasional exposure.

The shutter always takes 1/2 of a second to rotate around, but you can adjust exposure time by adjusting shutter angle. If you have the 11-position shutter, you can get exposures from 1/48 to 1/4 of a second.

The hardest part was figuring out how the Aaton does both test and run on a single pin. The pin seems to be a 12 volt source behind a ~300 Ohm resistor. If you pull the pin down to the 3-10 volt range, it'll enter "test". Pull it down any lower, such as by connecting it directly to ground, and it'll enter "run".

Aaton's handgrip uses Zener diodes to pull the pin down to 5 volts precisely for "test", but since the camera seems to happily understand such a wide range of voltages, I just used a plain resistor.

Next steps would be: using the Lemo8 instead of the Lemo2 so that the Arduino can be powered from the camera, and putting everything nicely in a box, with a display, and switches or a knob to set the interval. I would also really like to figure out how the eShot does variable exposures, if anyone has any hints! The Aaton manual has pinouts for all the connectors, but really no details on how each pin works...

Here's some very basic example Arduino code. All it does is flash an LED and send a pulse to the run/test pin once every two seconds.

const int intervalMs = 2000; \\ set the number of milliseconds between each shot here

const int transistorPin =  12; \\ I put the camera on pin 12
const int ledPin =  13; \\ the Arduino includes an LED on pin 13, which I set up to flash with each shot, for diagnostic purposes
const int testDuration = 100; \\ how long to simulate a press to the "test" switch for. 100ms worked fine.

void setup() { \\ just putting pins in the right modes here
  pinMode(transistorPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
}

void loop()
{
  digitalWrite(transistorPin, HIGH); \\ "push down" the test button
  digitalWrite(ledPin, HIGH); \\ light up the diagnostic LED
  delay(testDuration); \\ wait a little bit
  digitalWrite(transistorPin, LOW); \\ "let go" of the test button
  digitalWrite(ledPin, LOW); \\ unlight the LED
  delay(intervalMs - testDuration); \\ wait until it's time for the next exposure
}

Josh Gladstone · August 17, 2015

I dig it! Old tech + arduinos makes me happy.

Edited August 17, 2015 by Josh Gladstone

Andries Molenaar · August 20, 2015

And 'test' exposes one frame? Seems more like it activates the lightmetersystem. As is often the case with cameras with one button for meter and expose.

Nima Khazaei · September 14, 2015

Whoops, missed this... Yes, "test" exposes and advances a single frame. The Aaton manual even suggests using it for manually-controlled time-lapses - see the note on page 37 here: http://www.my16mm.com/assets/pdfs/manuals/aatonxtrman.pdf

It does also activate the light meter. They're combined because the camera meters off the film, so it can't meter without exposing at least one frame.