Photographing a Speeding Bullet

I just created a new sensor and Arduino code that measures the speed of a bullet and then times the triggering of a flash to capture the bullet in a photograph.

Technical details about the projectile sensor I designed to capture these images are here: http://www.glacialwanderer.com/hobbyrobotics/?p=347

Let me know if anyone has any questions.

Wow! VERY nice pictures! I'd love to see more! :D

wow, i would say that are the most impressive pictures iv ever seen made possible with a arduino!!! :o

In all honesty they are good but not quite clear enough. I can't clearly see the bullet . It appears to be a ball bearing? Can you halve the exposure time . The triggering looks just right.

Air weapon at about 120ms-1, 25 us flash?

The first photo looks like a good use for a Christmas tree decoration :D

tytower, some of these do have the bullet frozen and others down. It all depended on how much light I needed in the scene and what effect I was going for. I liked some blur in the bullet because it indicates motion. On the ones that I did freeze the bullet in place I think it looks a little blurry because I was using a duel flash and the bullet is reflective which creates an optical allusion. Maybe I should do some shots with a painted bearing to make it look more frozen. Thanks for the critique. Constructive criticism like that can help make better pictures.

That said, I don't think my flashes would be able to freeze a real riffle bullet. If I wanted to do that I'd need a dedicated high speed strobe.

Do you mind me asking what you use for flash? I use a couple of old Vivitar 283s, which I've got down to around 30-40us. I'd like to get the duration down further, but the thought of dismantling these antiques and working on multi-kV circuits worries me some. Harold Edgerton is something of a hero of mine.

Yes thats fair enough but what I meant was to alter the camera shutter speed if possible to get a crisper image. Perhaps add more light if the shutter speed can be halved.

I had assumed the arduino was a trigger only and the camera decided the time the shutter was open . This may not be the case though.

Anyway great pictures none the less !

camera shutter speed

Ty, the flash duration here is almost certainly << 100us.
(work it out - a 6mm ball has travelled maybe its own length in the photos, whilst travelling at > 120ms-1)
There are precious few affordable cameras with a shutter speed of significantly less than 1/10000th of a second.
These photos were probably taken in near-total darkness, with the shuttter open or on its very slowest setting, and all the exposure is governed by flash duration.
Adding more light means adding more strobes which may not trigger at exactly the same instant, or making the flash longer, giving more blurring.

I think Arduino.cc needs some kind of "hall of fame" gallery for projects like this, because this is sooooo cool! :D

By the way kudos to the mods for removing all that spam from yesterday

There seems to be some confusion about about how I took these photos. Let me explain that a little better. (Awol, got it right.)

This sensor is used to trigger the flash and not the camera shutter. The shutter speed for most of these photos is about 5 seconds. The room is dark so all the light is applied to the scene from my flashes. I'm using two Canon 580EX flashes. The flashes are set to manual mode. At their lowest power setting the duration of the flash is less than 1/40,000th of a second (25 us).

I'm also a huge fan of Harold Edgerton. He did things that nobody else ever had done. All I'm doing is replicating some of his work in a much more affordable way. He also had a hardware advantage in that he used extremely expensive very high speed strobes that make my flashes seem slow. Perhaps making one of those should be my next project ;D Of course I have a hardware advantage in that the microcontroller has been invented and it makes my circuits simpler and more flexible.

The shutter speed for most of these photos is about 5 seconds.

There are precious few affordable cameras with a shutter speed of significantly less than 1/10000th of a second.

So which is it . I am having trouble understanding what shutter speed you are using . Seems you cant reasonably get the exposure time any lower is the answer , simple , just say that . Why all the beating around the bush ?

I thought he explained it reasonably well.

  • Turn off lights in sealed room.
  • Open the shutter in the camera.
  • Leisurely walk over to the gun's trigger.

Since the room is totally dark, it doesn't matter how slow you walk, or how long the shutter is open.

  • Fire the gun.
  • The bullet goes past the sensor.
  • The Arduino decides, "in X microseconds, the bullet will be through the target."
  • The Arduino decides, "it will take me T microseconds to make the strobe light flash.
  • The Arduino counts down (X-T) microseconds.

Around this time, depending on the value of T, the bullet strikes the target. Note that the T is not how long the strobe will be lit, it's how slow the communication might be, between Arduino and the strobe. For some strobes, it's extremely fast, a pulse on a signal line. For some strobes, an infrared conversation of coded pulses must take place, which can take some time. (If T is greater than X, then you'll have to have the Arduino trigger the gun, too!)

  • The Arduino sends the strobe trigger command to the strobe.
  • Time passes as the strobe listens to the signal. T microseconds.
  • The strobe goes off, producing a very short flash.

The light from the flash bounces off the bullet and target, and since the shutter is open, the reflected light from these and into the camera onto the image sensor.

  • The bullet goes on in total darkness, hitting a backstop.
  • The smoke clears.
  • Leisurely walk over to the camera.
  • End the exposure by closing the shutter.
  • Turn on the lights in the room.

The poster may have just set his camera to leave the shutter open for five seconds, saving him some walking around the room, but the concept is the same. Since the room is dark, it doesn't matter how long the shutter is open.

The duration of the flash drives the exposure time.

Canon 580EX flashes are not the fastest flashes out there, but they are a lot faster than the fastest available Tv (time value, aka shutter speed) that you can set on the camera. Other strobe types are even faster, pumping out the same total amount of light in a shorter period of time.

The point is that for all practical purposes, shutter speed is irrelevant.
The exposure is controlled by the duration of the flash.
A flash duration of 25us equates to an effective shutter speed of 1/40000th of a second, but the chances of triggering anything (i.e. a mechanical shutter) but a CCD gate signal accurately enough to capture a speeding projectile is all but a waste of time.

FYI 1/10000th second is less than 5 seconds.

BTW, I had a look, and there is a (roughly) $1000 Casio camera with a shutter speed of 1/40000th of a second, but I wouldn’t try to trigger it accurately enough to capture a speeding projectile and sync it with a similarly short flash.

BTW, I had a look, and there is a (roughly) $1000 Casio camera with a shutter speed of 1/40000th of a second, but I wouldn't try to trigger it accurately enough to capture a speeding projectile and sync it with a similarly short flash.

The new high-speed Casios are actually 1000fps+ movie recorders, and they make it pretty easy to capture a movie or a moment with a given event in the middle of a ten second burst. The downside is that you have to be pumping enough light into the scene for ALL of the frames, not just the one frame of exposure. Edgerton shots like this take up a lot of energy and can make for a very hot studio.

Seeing the compression waves on the impact side in that first balloon picture is very cool!

The new high-speed Casios are actually 1000fps+ movie recorders

The Casio (EX-F1) is also a high-speed still camera, with a claimed minimum shutter speed of 1/40000th sec.
Agreed, you’d need a lot of light.
Or a well-synchronised flash.
Which amounts to the same thing.
But I woudn’t want to try syncing the shutter with a projectile.

Other strobe types are even faster, pumping out the same total amount of light in a shorter period of time.

Seems like thats what he should try next then heh? Maybe you would let him answer for himself sometimes . That would be refreshing on this site

They are great shots, especially for home brew equipment.

I'm really looking forward to trying this myself and will be watching very closely to see where you take this.