Ballistics Photography
357 Magnum Bullets
Click here to see photos of 357 magnum stopped dead!
Technical Explanation
Firstly I started with a lot of thinking on the problem. How to capture a bullet in flight with a regular camera? A little pre thinking goes a long ways on a project like this, as I had no previous experience in photography of any kind other than your typical family picture taking.
My fastest shutter setting on the camera was one two thousandths of a second. Not near fast enough to stop a 357 magnum bullet traveling approximately 1100 ft/sec. I knew I must use the bulb setting which is the shutter locked open. This means the exposure must be done with the flash and in a completely dark enviroment. The auto exposure flash automatically adjusted the exposure time based on the light reflected back to the photo cell just below the flash window of the exion flash tube. As soon as enough light is reflected by the subject back to the flash an internal circuit, a thyrister, shorts out the flash tube to expose the picture perfectly every time, which I knew worked great from the pictures taken previously with this camera and flash. Normally in a completley dark room the flash, if triggered, would have a long exposure time, in the order of one sixtieth of a second. Fine for slow moving subjects but not a bullet.
The answer was as simple as a piece of tin fioil, arched between the very bottom portion of the flash window and the photo eye. This way when the flash was triggered light would immediatley be reflected to the eye and shut the flash tube off in the shortest time possable. This should give an exposure time as short as a flash tube can create which turns out to be very fast. I estimate about one one millionth of a second. Ah, that should stop anything, even a bullet. Sound seemed to be the ovious trigger source from a gun so I made a simple sound activated flash trigger using a small electronic amplifier with a mic at the input and an SCR, silicon controlled rectifier, at the output. The SCR is like a electronic switch which was used to trigger the flash unit.
OK thats it! The gun was mounted in a vise and pointed at a backstop sufficient for a 357 magnum. All lights out including ambient light. Camera and flash aimed at the expected bullet path with a backdrop of cardboard to allow the bullet to show against the background. Microphone set the distance away from the gun, the same as the distance I wanted to see the bullet out of the gun. This turned out to be almost the same due to the bullet velocity, 1100 ft/sec and the speed of sound, 1089 ft/sec being almost equal.
I must admit I amazed myself as the pictures here were taken with the first 20 exposure, Kodak ASA 400 colour film, and first attempt.
Maybe someone can use this idea in a new way for some other
high speed photography. It sure was fun. My friends still think the pictures
are fake and done with computer graphics, but not so!
