Tag Archives: ballistics

High-Speed Ballistics Photography with the Sony DSC-RX100 Camera

Over the past few weeks I have been using the StopShot control device, made by Cognisys, Inc., to experiment with taking photographs of drops of water falling into a tray of water and colliding with each other. Once I had some experience with the operation of the StopShot device, I decided to try to branch out to taking high-speed images of impacts from gunshots.

I don’t own a real firearm and I wasn’t interested in getting one, so I did some research and decided to use an airsoft gun. I learned that there are many models of airsoft guns available. Many of them are replicas of real guns, but all airsoft guns fire only plastic BBs.

I found out that there happens to be a well-stocked store that sells airsoft equipment about 10 miles from my home near Richmond, Virginia. Last week I visited the store and, after a number of questions, ended up purchasing an airsoft rifle made by KWA, the LM4 PTR, which looks and handles much like a real AR-15 automatic rifle used by the military and others. This rifle shoots plastic airsoft BBs with a diameter of 6 millimeters and a weight of 0.20 gram. Although I don’t know the exact figure, the rifle shoots with a velocity of between 300 and 400 feet per second (100+ meters per second). The rifle is powered by “green gas,” a special mixture of propane that comes in a can.

The gallery at the bottom of this post shows the setup I used, along with a few of the shots that I managed to capture using the Sony DSC-RX100 camera. (I could have used just about any advanced compact camera, but I used the Sony because of its large sensor and excellent image quality.)

There were many steps involved in getting everything set up to capture these images. Here is a brief overview. I purchased the CTK Precision P3 Ultimate Gun Vise as a stand to hold the rifle firmly. With the rifle in that stand, it was somewhat tricky to get it lined up so that, when it fired a BB, the BB would travel between the two infrared sensors connected to the StopShot. When the BB interrupted the infrared beam, the flash connected to the StopShot (a Yongnuo YN-560 III flash) would fire after a delay to allow for the time it took for the BB to travel from the beam to the target. (This delay worked out to be between about 3 and 4 milliseconds.)

The flash was aimed at the target area, which was placed inside a cardboard box for safety. I cut out a part of the box and taped on a sheet of hard, clear plastic to make a protective window. The camera was set up outside that same window and was focused manually on the area where I expected the BB to hit. For each shot, I set the camera’s self-timer for a 10-second delay and used Manual exposure mode with a shutter speed of 1 second at f/9.0. I used the long shutter speed so the shutter would stay open to allow the action to be frozen by the flash. I kept the room darkened so there would not be much ambient light to interfere. I set the flash to its lowest power, 1/128 of full power, so the flash would have a very short duration and be able to freeze the rapid flight of the BB.

Once I pressed the shutter button to trigger the camera’s  self-timer, I moved quickly to the rifle and got ready to fire it. As soon as the camera’s shutter opened for its 1-second exposure, I pulled the trigger on the airsoft gun. Almost immediately after that, the BB penetrated the infrared beam and the flash fired, freezing the action as the BB moved through the target area.

In each image shown below, the gun was fired from the left side. In some shots you can see part of a target and the pellet trap that was set up in the back of the cardboard box to trap the BBs. Despite that setup, a good number of BBs went flying all over the room, making me glad I had my safety glasses on.

As you can imagine, it took a lot of trial and error to get the aiming and timing worked out to the point where I started to get some interesting images. You can see the setup and the results so far in the gallery below. I hope to keep working on this project so I can get some better images, but I was pleased that I was at least able to catch a few images of the black BBs as they flew through the targets.