Open-flash technique is a simple method that most photographers use when capturing high-speed events. Here’s the process:
1. The image is taken in a room with low ambient light, the darker the room the better.
2. Open the camera shutter.
3. At the right moment, trigger the flash (i.e. manual trigger, or sound or IR trigger depends on the event).
4. Close the camera shutter.
Most of high-speed events are being captured using this technique, that is why this is also called as high-speed photography technique.
The flash will be the only source of light in the room, this makes the ‘thousandth of a second duration’ achievable. Note that on this method, camera shutter speed is irrelevant. The event duration will come from the duration of the flash, which is ~ 1/800 sec @ full power, and can be lowered to < 1/10000 sec @ 1/128 power (heavily depends on your flash). The flash freezes the motion of a high-speed event, not the camera shutter speed.
On Camera Setting
Put your camera on full manual mode. Put the shutter speed in Bulb. If your camera does not have bulb, just use the highest value possible, i.e. 30 sec. Determine the appropriate aperture value. Use the lowest ISO value possible to minimize noise.
Use manual focus. Pre-focus first on where the image will be before clicking the shutter.
I strongly suggest to use the flash off-cam. Shutter lag of the camera can affect the timing when triggering on-cam flash.
Do not use TTL, use manual. Adjust the flash power to correct the exposure. But keep in mind that the lower the setting of the flash, the faster its flash duration, and the sharper the image will be.
Since in HSP, we want the image as sharp as possible and we hate blur, the following are suggested:
1. Use steady tripod. Yes, not just any tripod, but a steady one.
2. Use remote camera trigger.
3. Enable mirror lock-up.
4. Turn-off IS or VR (or whatever-you-call-it), if applicable. Remember your camera is in a steady tripod, so no need for them.
5. Pre-focus before you hit that shutter. Make sure that the image is in focus.
6. If possible, check the captured image in a larger monitor, not on your little 3.5″ camera LCD. Check the clarity, sharpness and focus of the captured image, and adjust if needed before shooting again.