Creating Complex Camera Trigger

[Drew Fulton]

Greetings,

I am a professional wildlife photographer looking to do some remote tripwire photography and create my own device. I know there are commercial products out there but I am hoping to save some money, customize the device, and learn more about electronics.

I have a background with basic physics and understanding of electronics from a high school classroom position but less of a realword experience. I would appreciate any help or even comments about the feasability of my project.

I am outlining a very complex device here with lots of options. The basics I need are a single laser or option for two lasers in paralell that when broken, a camera is fired. In addition, when the laser circuit is broken, the lasers must be turned off until the system is reset to prevent a red dot from showing up in the photographs. The delays and multiple camera attachments are not as important but if I can include them it will make the device much more useful. Additionally, the entire device including lasers (not cameras or flashes) must be powered by a battery of some sort, 12V will work if necessary.

COMPLETE PROJECT DESCRIPTION:

TERMINOLOGY:

Trigger - To fire either camera or flashes
System Reset - When system is prepared for another trigger. Turn on lasers, prepare camera(s) or strobe(s).

REQUIREMENTS:

1) I need a laser beam that when broken provides a trigger.

2) Ability to use two beams that when both broken, provides a trigger.

3) Optional: IR sensor that has broader beam than laser that when broken provides a trigger.

4) To Be Added Later: Sound sensor that provides trigger when loud noise is sensed.


BASIC OPERATION:

1) To fire a camera or flash, a circuit must be completed without any voltage passed through that circuit.

2) I would like to be able to fire multiple cameras with optional delay between cameras.


OPERATION MODES:

1) Standard Trigger - When Trigger occurs, camera or flash circuit is pulsed.

2) Bulb Mode - When Trigger occurs, flash circuit is pulsed. Meanwhile, camera circuit is completed and released on a variable timer.

3) MLU (Mirror Lock Up) - When Trigger occurs, camera circuit is pulsed to fire shutter. When System Reset occurs, camera circuit is pulsed again to raise mirror.


OPTIONAL TIMING SETTINGS:

1) Shutter Delay: Time between trigger and completion of camera or flash circuits.

2) Reset Delay - Time between trigger and system reset.

3) Pulse Length - Time that circuit remains completed after trigger occurs (used for shooting multiple images in bursts).

4) Bulb Interval - Used for bulb mode where camera shutter will be held open for X time then closed and open again. When Trigger occurs, flash fires.

5) Multiple Camera Delay - When multiple cameras are attached, provides amouont of time between the firing of each camera.



So that is it at the moment. Again, as of right now not all of these need to be built in to the system at this very moment but the more options and features included, the more flexibility this device will allow.

Thank you for all of the help and I look forward to learning from the experts here.

Best,
Drew

 

[pc88]

Drew,

Have a look at Make Magazine's Homemade Strobe Photography Project:

**broken link removed**

There's a schematic on that page, and there's an article at:

https://www.electro-tech-online.com/custompdfs/2008/03/strobephotography.pdf

which explains how the circuit works. Even though this device triggers a flash, triggering a camera shutter is not that much different.

To perform the complex triggering you'll want to use a microcontroller. The latest version of the Quaketronics High-Speed Photography Kit is uC-controlled and has an In-Circuit Programming Connector so you can replace the firmware. You might see if other people have modified it to act as a shutter controller instead of a flash controller.

The Quaketronics link: **broken link removed**

 

[hunt4it44]

perhaps you have already been to this sight, but have you tried hagshouse.com? there is a whole web community for making homemade game cameras and game videos. I don't know that I have seen anyone use the laser approach, but there are great discussions on different cameras, triggering mechanisms and controls.

 

[astronomerroyal]

Dear Drew,

I read with interest your post and took a look at your photographs - very good indeed. I was in a similar position last year, although I'm merely an amateur wildlife photographer. Nevertheless, I wanted a remote camera trigger.

I built one which satisfies your basic requirements. I think you have the right approach, starting with the basics. As mentioned, the microcontroller would probably be best for implementing all your requirements, although much of it can be done with basic electronic components (e.g. 555 timer circuits).

As I'm self-taught and undisciplined I don't have any fancy circuit diagrams for you, however I can describe how I went about it.

The circuitry is basically made up of circuits found in Forrest Mims' Engineer's notebook Vol. 1. To understand the electronics/physics you'll need a book like mims' 'Getting started ...' book or Scherz's 'Practical electronics ...' book.

A) I use a laser-pointer, which is pulsed by a simple 555 timer circuit (e.g Mims). Flashing means that the laser is on only 10% of the time, and so the batteries last 10 times longer. more importantly a flashing light source can be easily 'differentiated' from, say, steady sunlight - which will be important if you want to use the device in daylight.

B) The trigger must obviously look for missing pulses (i.e when the animal breaks the laser pulse beam. Again Mims has a 'missing pulse detector' circuit. I actually added a 'high-pass (aka differentiator)' circuit before this in addition to a 'comparator' in order to separate the sunlight signal form the pulsed laser signal - the comparator essentially makes the result 'digital'. this is a nice clean signal (i.e. largely free from electrical noise) to feed into the 'Missing pulse detector' circuit. It's not essential though.

C) when the missing pulse detector circuit detects a missing pulse it fires a 'monostable 555 timer circuit' (Mims again) which send sthe trigger signal. the duration of which can be adjusted (i.e your 'pulse length' criterion). Actually the trigger signal fires a IR photoemitter/phototransistor coupler, which is what is equivalent to pressing down the shutter button. Note also, the camera is electrically isolated from the device.

I've attached some photos of the gear, the devices it can fire (camera, flash, pocket wizard all just require a short circuit to fire), and the laser and detector. The circuit that pulses the laser is in the film canister.

If you want two beams then you just pulse them synchronously and combine them with a basic 'AND' or 'NAND' logic circuit before entering the black box.

To fire multiple cameras I'd just have the deice fire a pocket wizard which fires several cameras (each with a MultiMax pocket wizard attached - expensive, but versatile). Alternatively you can achieve different delays by using 555 timer circuits. The 555 chip is an amazing thing.

As for your 'Bulb mode': my speedlite flashes have a strobe mode, so that functionality doesn't need to be built into the laser trigger.

Most

 

[astronomerroyal]

as I was saying... to achieve all of your criteria I would look at a microcontroller, although the wonderful 555 timer chip is capable of doing the job.

If you were wondering, the big red knob is the pulse duration. The two small red knobs are for tuning the device to the incoming pulses and adjusting the sensitivity of the detector. There's a green LED confirmation light, and a test-fire button to simulate an event.

Incidentally, since the laser is on only 10% of the time, it rarely appears in a photograph, and even if it does the laser spot is usually invisible, being so much fainter than sunlight. The detector is just a CdS detector hidden at the end of that black baffle.

Wrap-up: most trigger devices use a steady laser beam, and this is much easier to implement, although with Mims' circuits it wasn't difficult for me to do. A few months ago I started to look into microcontrollers in order to design a trigger that has all the functions you describe. To be honest teh commercial triggers don't do anything that we homebuilders can't make ourselves.

Please *email* me with your progress (I think you can email me through this website), I'm only on this forum because of the microcontroller stuff and because my monthly googling for 'laser trigger' brought me to your post. I don't come here often but I'd be happy to discuss ideas.

P.S. I should add that I mentioned the MultiMax pocket wizard because you can set it to fire a camera/flash/whatever with a programmed delay - one of the things you wanted.

 

[astronomerroyal]

Forgot the photos....