DIY Air Gap Flash Saves At Least Seven Grand

Did you know that a standard camera flash is much too slow to capture high quality images of bullets? A relatively long flash duration results in blurred images of the bullet. By building this air gap flash a bullet can be frozen in mid-air, producing some stunning results. There is an element of danger here, and not from the bullet. This flash uses a 35,000 volt capacitor to produce the mini-bolt of lightning which serves as the light source. The unit can be built for a few hundred dollars, which sounds like a heck of a deal if commercial models really do start at $8k and go up from there.

Now that the photographer has a super-fast flash, a camera axe takes care of the timing… which is everything.

27 thoughts on “DIY Air Gap Flash Saves At Least Seven Grand

  1. Wow. I was reading through the tutorial, yeah, yeah, wow wow…then I realized that he fabricated his “bulb” almost from scratch. DIY “filaments” (I know that’s not what they really are…arc points maybe?). Anyway, I was just blown away by how DIY it is. Looks great [5]

  2. Thanks for all the kind words folks. I’m glad you liked it.

    Stuckatwork, I didn’t really think of it as making my own bulb. On the first test I didn’t have the outer glass protector on and there was a loud thunder boom when it went off. That outer glass test tube is really there for safety and to reduce noise. Now it only sounds like a quiet thunder boom :)

    Hackius is correct. These pictures are taken in a dark room and the camera usually has an exposure of a few seconds. Here is an article I wrote about how this part of it is done:

  3. @User
    You can use lots of light (sunlight) and trigger the camera the same way, but you first have to measure the delay of the shutter from button press.

    A method for initial testing could be to use a stopwatch and your camera wired in parallel with a switch. The switch activates both devices and you should get a photo of the stopwatch, now you have a rough delay time that you can increase or decrease to capture really fast objects in light!

  4. @Maurice
    Excellent work. Is the HV supply just a diode/capacitor ladder? In the pictures it looked nothing like the kit you linked to.

    That works to a degree, but you have to deal with the blur of the shutter. Physical shutters work, usually, with two moving curtains. One moves and starts exposing the sensor or film, the other follows it and blocks light. The sync speed of the camera is the speed that the camera has the front curtain fully open, and the sensor/film fully exposed, before the rear curtain starts closing, usually around 1/60s to 1/250s. To get a faster shutter speed, the rear curtain begins closing before the front curtain gets fully open; you still get a lag of about the sync speed from the image captured on the left of the frame to that on the right. If the bullet happened to travel at the same speed as the shutter, you might even have a more blurry picture.

    Fully digital shutters can work completely differently. With the right sensor and shutter combination, you wouldn’t need a strobe light. But last I priced those, they were more than seven grand.

  5. The red ball mentioned in one of the comments is plastic. The bullet used appears to be an “Air Freedom” round manufactured by Extreme Shock. It is used by law enforcement aboard aircraft because it will shatter upon impact and not pierce the skin of the aircraft. That’s a great picture of it doing what it was designed to do.

  6. Quin, it is just a diode doubling ladder. It starts with a 2000 VAC supply and doubles that several times to the voltage I want. I was going to mention that in the blog but I forgot. Good catch.

    The idea of digital shutters gets me excited. I’ve started down a diy digital shutter path a few times, but have never figured out a way to make it practical. If I ever make progress here I’ll be sure to post it, but don’t hold your breath.

    On a side note even a separate mechanical shutter would be interesting for some shots because you could reduce shutter lag. There are a few people who have done this with a harddrive motor.

  7. Very cool. As far as the camera shutter vs. flash exposure method, it is pretty common in studio setups to go in the flash direction, particularly when sync is an issue.

    I used to do the “bullet cam” effect with 12 old Nikons by setting the shutter to open and using the flash as sync. Much simpler then trying to get reliable shutter sync.

  8. I think that one could make an interesting flash with avalanche transistors and some laser or LED diodes of various types… Fall times on the order of 10 ns is easy… Might not even need avalanche. Might be safer. Might require even darker room with even faster lens though if you can’t make the flash as bright.

  9. Brian, I did some calculations with big 1W LEDs before I started this project. Even if you have a 100 of them they just don’t produce enough light in 1 us. I can’t remember exactly what I got, but it was a few orders of magnitude too little light. I wasn’t overdriving the LEDs, because the datasheets didn’t contain that info, but I was far enough away that I knew overdriving the LEDs wouldn’t make them bright enough.

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