High Speed Photography The goal of this experiment is to capture a high speed event as a single moment in time. You will be popping a balloon and capturing the image of the balloon mid-rip using a Nikon D70 SLR camera. 1.) Place two ring stands on the table and drape a black cloth as a backdrop between them. Blow up one of the balloons and place it centered and in front of the backdrop. 2.) Set-up the two flashes. Attach each flash to a ring stand using the clamps, change the angle of the flash to 90 degrees, and place them apart from each other opposite, but flash facing, the balloon (as in Fig 1). Figure 1. Set up with flashes and backdrop a.) You’ll need to set up the flashes so that they go off as the balloon pops. Take a microphone (Fig 2) and plug it into the boom box. Make sure the switch on the wire reads “on.” Take the wires from one of the circuit boards in Fig 3 and plug the gray wire into the boom box while the red and black wires plug into the flash. You only need to plug the wires from the circuit board into one flash. The other flash, the Slave flash, will automatically go off as the flash connected to the circuit board goes off. It has a light sensor that picks up on the light given off by the other flash and this signals it to flash. Figure 2. Microphones Figure 3. Circuit board connecting flash and boom box. b.) Inside the cassette holder in the boom box there’s a little white tab like in Fig 4. Push it and keep it held down. Then click the play button and the record button at the same time. Pushing down the white tab tricks the boom box into thinking there’s a tape inside. Figure 4. Finding the white tab Now when the balloon pops the microphone will register the sound, it’ll send the information to the boom box, the boom box relays the info to the flashes and they’ll go off. 3.) Take the camera and put it on the tripod facing the balloon. Turn on the camera and turn the main command wheel on the left to “M”, or Manual. You’ll need to change both the exposure and the aperture before you take the picture. a.) Exposure is the amount of light that you allow the camera to be exposed to in seconds. For example, if you set it to 10, then the exposure will be 1/10 of the second. If it’s at 10”, then the shutter will stay open for 10 seconds. Push the button labeled “AE-L/AF-L” on the back of the camera as shown in Fig 5. Use the subcommand wheel directly right of this button to change the exposure to 2.5”. See Fig 6 for the location of the exposure reading. b.) Aperture controls the depth of a picture. A larger aperture means more light will enter the camera and the background will be sharper. The camera will also take a faster picture in lower light. To change the aperture, rotate the dial found in front of the shutter button until it reads “f 22”. Again, see Fig 6 for the location of the aperture reading. Figure 5. Changing the exposure Figure 6. Finding the exposure and aperture 4.) Now you’re ready to take the picture. Have one person in charge of the camera, another ready to turn off the lights, and have the last person ready to pop the balloon. 5.) Turn up the volume on the boom box (Fig 7). Have the balloon popper hold the balloon in place with one hand and hold the pin taped to the ruler in the other. Turn off the lights. 6.) Hold the shutter button halfway down and when the balloon popper is ready, push it all the way down to take the picture and then let it go. The instant the balloon popper hears the camera shutter taking the picture, pop the balloon. Let the camera finish taking the picture. 7.) IF your picture is black, then you might need to fix the balance (Fig 7). Look and see which port you plugged the microphone into on the boom box. If it says right, turn the balance knob to the right. If left, turn left. This turns up the volume to the microphone so the boom box picks up on it faster. The balloon popper may also be popping the balloon too early or too late. Figure 7. It’ll take a little experimenting, but the resulting picture should look something like this: