DIY Sound-Activated High-Speed Photography

eldavojohn writes "Have you ever wanted to catch the perfect photo with your SLR camera but couldn't time the shot just right? Photography enthusiast Matt Richardson brings us an instructional video over at Make Magazine that shows how to use some very basic breadboarding and an Arduino Nano to do some high-speed flash photography that is timed by sound instead of your finger hitting the button on the camera. He pops a balloon and smashes a wine glass to show some results. His code is available on Github, and you can find more of this sly hardware hacker on his YouTube channel."

Comments

OK

[hjf]

Seriously, why do we need an Arduino to make a sound trigger?

Oh yes, all the cool kids use arduinos now, so if you make an electronics project without one, no one is going to read your article.

Re:OK

[OzPeter]

Oh, you mean your camera doesn't run Linux. How odd

I used to have an HP dig cam that allowed you to write programs against a public API, that you could load into the camera via the CF card and then run from the camera.

Re:OK

[Yvan256]

Food, water, a cave and high-speed internet.

Re:OK

[JustinOpinion]

Well an Arduino would not be the right choice if you were building a large run of a commercial product. But we're talking about DIY here. The advantage of using something more powerful and general purpose like an Arduino is:
1. Easier to rapidly prototype, tweak your setup, or add features. (It's faster to re-code your Arduino than to rewire some electronics you soldered.) You can increase the scope/complexity of your project quite easily.
2. If you're already familiar with the Arduino, and have one on-hand, it's faster/easier/cheaper to use that. (Again, not everyone has a box of Arduinos, but the DIY-ers that this tutorial is aimed at may very well have some on-hand.)
3. When you're done with this project, you can remove the Arduino and re-purpose it easily.

Obviously you can make a cheaper/faster/more-efficient sound trigger using equipment more basic and specialized than an Arduino. (You can also build far better toys using dedicated materials rather than Legos.) For playful building/testing/etc. using an Arduino is quite useful. And, yes, there is an advantage to a DIY community ("all the cool kids") settling on a common set of general-purpose tools, since it lets them exchange design plans, code, experience, etc.

Re:OK

[Caradoc]

Seriously, why do we need an Arduino to make a sound trigger?

I agree that the Arduino is overkill for a basic sound trigger - but projects like the Camera Axe make a lot more sense. I use a variation on the Camera Axe for photographs of lightning among other things.

Re:OK

[hjf]

Discrete components. Google for "sound trigger" and you'll see how easy it is to build one out of an opamp or even 2 transistors and a few resistors.

Re:OK

[OzPeter]

Yes. But this "system" just fires the flash. It doesnt do anything else.

Ummm .. You didn't watch the video did you?!?!!?

Re:OK

[Technician]

I did this in the 1970's for a photography project using an SCR to handle the high strobe trigger voltage (used to be ~160 volts on the shutter contacts) and the amplifier from a portable tape recorder to amplify a microphone to enough voltage to trip the SCR. With a strobe mounted off the camera and the camera on bulb setting, I took pictures of light bulbs crashing onto the sidewalk. Due to the lighting angle, most people thought it was taken in the daytime in sunlight. I adjusted the delay after impact by changing the distance of the mic from the bulb. 6 feet provides a good delay. With the mic too close, the bulb looks like it is sitting on the sidewalk with a few cracks in the glass. The delay was necessary to get the bulb in a reasonable amount of shards.

Re:OK

[Eil]

Because otherwise there wouldn't be anyone to complain about it on Slashdot? Do you read your email in pine over a serial terminal too?

The photographer had minimal electronics experience and simply used what knowledge and equipment he already had on-hand to create a useful hack. The great thing about Arduino is that it's flexible and simple. It allows people to slap together all manner of interesting projects without the benefit of an electronics engineering degree. In fact, it was explicitly designed as a way for artists and non-geeky folks to add basic electronic features to their projects. So what if it's overkill for a purpose like this? For the hobbyist, one Arduino board beats having to stock dozens of common single-purpose ICs.

Re:OK

[bill_mcgonigle]

Seriously, why do we need an Arduino to make a sound trigger?

To generalize your question:

Why do we need an Arduino to ___________?

I'll take a stab at it: Because it allows a software developer to do things that previously required a hardware developer (EE), for certain problems. This unbinds prototyping from a certain educational requirement, opening the field to more participants. For one-off projects of value, the cost of an Arduino board may be low enough to be considered negligible.

It's exceedingly doubtful anybody would go into mass-production with an Arduino-based design, unless time-to-market or field upgradability were the ultimate criteria, or the volumes were low enough that hiring proper engineering would not be cost effective.

Re:Quicker Than Sound

[bucaneer]

Real life, macroscopic events (i.e. stuff you'd want to photograph) happen at speeds that are closer to the speed of sound rather than that of light, so catching the very first wave of photons probably would not be very useful practically, not to mention insanely more difficult.

I saw this done in the 70's!

[Announcer]

Back then, a similar project used op amps to trigger a flash unit. It was an article in one of the electronics mags I saw back in the late 1970's, titled "Build the Thunderbolt". (I Googled it, but came up empty.)

You adjusted the timing of when the flash was triggered, by moving the microphone closer or farther from the sound source. You could also have added a 555 timer, if you needed a longer delay than was feasible with a longer distance.

It reminds me of a discussion at the Electronics firm I am consulting for. They needed to add a 1/2 second delay to the startup of a device in a new product. I suggested they add a 555 timer circuit. They looked at me like I had two heads. Their solution was to throw a microcontroller into the product. Come on, guys! It can be done with a 555, a cap, and two resistors. It's crash-proof, too. Whatever happened to K.I.S.S?

Re:Quicker Than Sound

[djlemma]

Also, the thing about this type of high speed photography is that you're triggering the light source... so if you're trying to photograph something that creates its own light, these strobe-triggering devices are going to do you no good at all.

To do that, you'd need to trigger a high speed shutter, which is a lot harder to do.. there's usually a lag between when a shutter is triggered and when it actually takes a picture, and the mechanical shutters on most SLR's don't actually go much faster than 1/250s. The images you see of matches being struck and explosions happening and such are taken with motion picture cameras with very high framerates.

Although, with electronic shutters that are becoming more common, there might be a way to get actual shutter speeds of 1/8000s with minimal lag. Could be very cool.

Re:Quicker Than Sound

[pz]

Seeing how light travels much faster than sound, my initial reaction is that this is a terrible idea.

Didn't bother viewing the linked video, eh?

The idea works pretty well because things with mass tend to move slowly, so despite the latencies involved and differential speed of sound and light, the described mixed digital / analog device works quite well to capture a mid-pop baloon or breaking wine glass. But then there are all of those classic Doc Edgerton photos that were taken with just analog circuitry, and they worked fine, too. Indeed, Prof. Edgerton made quite a career for himself at MIT using just this idea. So, despite the perhaps 10 seconds of thought you put into the problem before composing your negative reply, the idea has merit.

need for copylefted educational photos

[bcrowell]

For a long time, the famous Edgerton photos were a staple of physics textbooks. E.g., you could see the (huge) deformation of a tennis ball being hit by a racket. But the Edgerton images are all copyrighted, and it would be really helpful to have CC-BY-SA-compatible photos that could be used instead in places like Wikipedia. I'm the author of some copylefted physics textbooks, and I really haven't been able to find much that's useful. There's this category on wikimedia commons, but there's currently not much in it that's useful educationally. IMO there are a couple of things that would be useful in physics education: (1) an image like the tennis racket, showing how an object's center of mass accelerates even while it's in contact with another object; (2) an image like the bullet going through the apple, which I believe shows that the speed of sound in the apple is less than the speed of the bullet.

Re:Quicker Than Sound

[djlemma]

Even better... Just open your camera's shutter and put your hand in front of the lens until you see a lightning strike beginning. Remove your hand for just the amount of time that you see lightning. Then, put your hand back without closing the shutter. Repeat for however long you want to leave the shutter open, say 30 seconds. If you capture a few lightning bolts this way, you end up with a shot that looks like Zeus was VERY angry.

Re:Quicker Than Sound

[Monkeedude1212]

6ms is long enough for something (like a balloon starting to pop) to happen.

Most people, if they try hard enough, can count to 10 aloud in 1 second. That means they are speaking with the capable thought around 100ms. Now, just imagine how high you can count in your mind, not speaking aloud, in 1 second. How many instant thoughts can you get? How many milliseconds is it to process the next number in your counting scheme for you?

Now try watching a baloon pop. Try capturing that moment where the shape is Juuuuust starting to rupture - even though it's no longer holding the air in. How fast do you think that went? It wasn't like 1ms, but it wasn't 100 either.

The big thing to consider is the technically difficult issue of trying to get the baloon to pop and take a picture based on "Light" - something I think the GP completely overlooked. The reason we use sound is because its easy to set up a trigger for that - because the trigger is actually the baloon popping, not our own specific timer. A baloon doesn't produce a flash of light when it pops - so you can't use light to set off your photo, unless you are trying to detect the difference in shape of the baloon on a really tiny scale and hope it sets off your radar triggers or something incredibly complex - because simply timing the photo with your needle doesn't always work.

Sound is simply the simplest way.

Re:Quicker Than Sound

[lee1]

You don't need a flash for fireworks either. So why am I surrounded by people taking flash pictures of the sky whenever I go to a fireworks show? So far I have been able to resist grabbing them by their collars and screaming at them, but I'm not sure how long I can hold out.

Re:Quicker Than Sound

[johnlcallaway]

Taking photos of lightening at night is very doable using this method. But not when you are trying to take some of the most beautiful lighting pictures ... which occur during the day. Using your reflexes to time shutter open/close is more luck than skill. Even at night, depending on the dSLR camera, the amount of time it takes for the camera to process a bulb setting and store the image can introduce long delays between shots, and missed opportunities. Bulb settings increase the noise in a shot the longer the shutter is open. Turning off the camera noise processor and doing it in Photoshop reduces in-camera processing time significantly, but it can introduce odd bits of color scattered around the photograph that require touchup.

That's why they sell lightening triggers that use the lightening flash itself to trigger the shutter. Camera lag is an issue, but not with the higher end cameras.

I only use the nighttime long-exposure method as the lightening triggers are a little pricey for my taste.