will england :: [] : stopping a bullet

NOTE -- I haven't actually *done* this hack, but I have it here for your information and reference. Be sure to also look the additional information at the end of the page.

This is an original post to the Usenet newsgroup alt.hackers by Paal Hammersmark.

From: [email protected] (Paal Hammersmark)

Newsgroups: alt.hackers

Subject: .45 ACP/Camera Hack (long)

Date: 13 Oct 1994 23:43:10 +0100

A real hardware hack... :-)

ObFreezeTimeHack: As a hobbyist IPSC shooter, and amateur photographer I decided to take a picture of a live bullet "in flight". I had no access to high-speed cameras, so I had to solve it with an ordinary 35mm camera. The minimum shutter speed of my camera is 1/8000s, wich is hardly enough to "freeze" a normal charged 230 grains .45 Auto bullet. I chronographed the bullet to 780 fps. This means that the bullet travels approx 1.2" (2.9cm) in 1/8000s. Besides, it would be very hard to sync the camera shutter to catch the bullet as it passes the lens.

I also had an electronic flash. From the manual I found out that it could deliver flashes of only 1/20000s duration under certain conditions. It is also simple to trigger an electronic flash. I built a cheap trigger circuit from a CMOS inverter and a transistor.

On a bottle I glued a thin ribbon of aluminum-foil in an arc. The ribbon acted as an old style window-burglar alarm. When the bottle broke, the ribbon tore apart, and the trigger circuit fired the flash.

On an indoor shooting-range, I rigged my camera, flash, bottle and trigger circuit. Downrange I lit a candle to aim at, because the picture had to be taken in darkness. I set the shutter on the camera to "BULB" (open), loaded my gun, aimed at the bottle and fired - FLASH! The result is an almost crystal clear picture, showing a bottle broken into thousands of pieces, but still standing on it's bottom like nothing happened. The bullet can be seen on the exit side about 1" >from the bottle. There is a "mist" of small glass fragments on both the entrance and exit side of the bottle.

ObSecondFreezeTimeHack: Because the bullets travels slower than sound I modified the trigger curcuit to respond to sound. In this way I could take pictures of the bullet leaving the barrel. I took a series of pictures in all phases of a gun-cycle by varying the distance between the microphone and the gun. This learned me a lot of what's really going on when you fire a gun.

WARNING: Guns should be handled with care! The above experiment was practiced under safe condtitions. Be careful if you are going to try something similar.

More information on stop-motion photography:

Well, after about 50 e-mails asking how I did this, where do I get the equipiment, and where is the picture, I'm finally putting some contnet on high-speed flash photography here.

Perhaps, one of these days I'll even get around to taking some stop- motion photos!

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