Slashdot Mirror
Photographing Exploding Edibles
Isaac Skibinski writes "Remember gawking at photos of bullets going through apples (and the pretty fruit gibbage)? We've recently built an apparatus to capture similar results, using a BASIC controller stamp, a disposable camera flash, an air compressor, an electronic sprinkler valve and some pipe. Considering the cost of the device, it has allowed us to take suprisingly crisp photos of high-velocity objects."
don't sit too close to the end of the barrel, like Isaac did.
That's not so bad. The real Isaac stuck a knife in his eye just to see what would happen.
--
In London? Need a Physics Tutor?
American Weblog in London
I built one of those slave flash thingies somewhere in the mid '80s ... combined it with a microphone and a old Praktica reflex camera...
(total kit was about $80 worth of cam and electronics...)
I had about the same results, only then using black and white photo's.
I think I am going to start one of those sites too. I am just as much a nerd as these guys!
My thoughts start heading toward what other fun (AND educational ;-) ) things can be done with the strobe photography rig besides blowing up fruit...
(I think I see $40 leaving my wallet in the very near future)
These guys went through all that trouble and are only shooting a nail through a cracker? Come on, there are so many cooler things then that.
/. poll.
- Nail into water ballon
- Nail through fragile glass
- Nail into steel (watch nail bend)
- Nail into neighbors cat (okay, maybe not such a good idea)
We could even make it a
I have an uncle who assists police with forensics work (he's a dentist during the day, but the town he lives in is small and they need all the help they can get).
One thing that stumped the police was a scene where a single bullet came through the windshield of a car and hit the driver.
That in itself wasn't surprising. What was surprising is that the back of the guy's head got completely blown off - a really huge hole that they couldn't explain at first.
So they did an experiment using high-speed film/camera in a lab, where they got a few windshields to play with and a few human skull mockups, and a gun with bullets of the same make/model as the one they've identified.
I saw a copy of (one of the) pictures they took, which was quite amazing (yet horrifying if you think what happened) - a giant cone of glass shards projecting outwards from where the bullet entered the windshield. The cone was small near the front of the driver's head, but while passing through the skull it continued on its outward path and blew a massive hole in the back.
Scary stuff.
You can accomplish anything you set your mind to. The impossible just takes a little longer.
Did it occur to any one that the use of the BASIC stamp was over kill. I'll agree it makes the project a little bit easier but these guys are MIT students. All you seriously need is a photo sensor, a transistor, an op-amp and a relay. Very simple. The only tricky part is that using this simple circuit would require precious placement of the photo sensor. This shouldn't be a problem if you know the velocity of the projectile which they know. You'd think some MIT nerds would have done it this way which is a little more elegant.
Only these guys used real guns, no some sissy PVC contraption: http://www.bitpress.com/dc/ The 7 cans is my favorite. :)
DRM 'manages access' in the same way that a prison 'manages freedom'
http://www.rit.edu/~andpph/exhibit-3.html
My favourite is the playing card shot half
I also took a lot of pictures of Exploding Apples. However, where this kid used a pneumatic gun and a flash camera, we used large pulses of current. In peak shots, we exceeded 2GW through the apples. Needless to say, they didn't make it.
The biggest difference between our methods, though, is the flash. Nails hitting the apples didn't produce any light, so he wouldn't get an image. We sat with the shutter open in a dark room as well, but all of our shots were simply lit by the light from the explosion. Note how the apples seem to be lit from within... Spooky. Here's a gallery of the various experiments in our HV lab.
-F
Using a quite similar approach, the guys from Frozen Reality take even more immpresive Pictures in 3D.
Their system is built from 8 identical digital cameras set up in a half-circle around the target object, all triggered by a single flash.
The images are processed my a morphing program and create stunning movies of exploding balloons, a metal ball crushing a stone plate etc.
Not just nice, but a great teacher as well. I took the strobe photography lab, and even though he was semi-retired he always hung around and would offer helpful but non-judgemental advice to anyone.
But what I thought was far cooler than the bullet-through-object photos, which were so easy you did them in the first few weeks, was the pictures of an exploding firecracker. Since it generates its own light, you can't use the darkened-room-with-fast-flash approach, but have to use far more sophisticated photo equipment with rotating slit shutters and stuff (you can't move the film stock quickly enough because it'll disintegrate.)
Man, I had a great time in that class.
I once went to a fabulous exhibit of his work, and it really covered an amazing range of subjects. People kicking footballs (interesting deformations), hitting golf balls, bursting balloons, and of course, shooting fruit and playing cards.
One of the most interesting things was research into nighttime arial photography of germany during the war. He was an expert on high power flashes, and that was part of the project. Didn't work because it wound up lighting up the whole sky, and giving it all away.
The best quote was when someone came into his lab to ask if they had a deck of playing cards to lend out. His answer was "Nope, shot 'em all up."
...discovered it made an excellent fire extinguisher(fill barrel with water, cork, aim, blammo- between the gust of air and the water/steam, you could do a serious number a good sized fire with just two cups of water).
This technique is now being used by firefighters to fight high-temp fires that are inaccessable by vehicles, such as in tunnels. Three or four blasts from the backpack fire extinguisher into a fire that's melting cars, and you can walk right into it. No weird chemicals needed either.
I've finally had it: until slashdot gets article moderation, I am not coming back.