Understanding sync speed is crucial if you want to master flash photography. Whether you're using studio lights or speedlights, knowing how your camera's shutter syncs with external flashes is a foundational step in working with artificial light.
Coming to you from Mark Wallace, this informative video explains sync speed and how it affects your flash photography. Sync speed is the fastest shutter speed at which your camera can fully open before the second curtain begins to close. This matters because, without proper syncing, your photos can have black areas where the shutter covered the sensor when the flash fired. Knowing your camera's sync speed, usually around 1/200th of a second, is essential to avoid these issues.
Wallace explains that your camera's shutter consists of two curtains: the first curtain and the second curtain. At slower shutter speeds, the first curtain opens fully before the second curtain starts to close. This allows the flash to illuminate the entire sensor. However, at faster shutter speeds, the second curtain starts closing before the first curtain is fully open, creating a slit of light that travels across the sensor. This is where understanding sync speed becomes vital. Using a flash at high shutter speeds without proper syncing will result in partially lit photos.
Wallace also introduces high-speed sync, a feature that allows flash to be used at shutter speeds faster than the sync speed. High-speed sync works by firing the flash in a series of rapid, smaller bursts instead of one single flash. This technique ensures the sensor receives even illumination as the shutter curtains move. High-speed sync is particularly useful for outdoor shoots where you need to balance bright ambient light with your flash and don't want to resort to using ND filters.
Understanding these concepts is not just about technical proficiency but also about creative flexibility. With knowledge of sync speed and high-speed sync, you can control and shape light to suit your creative vision. Check out the video above for the full rundown from Wallace.
If you would like to continue learning about how to light a portrait, be sure to check out "Illuminating The Face: Lighting for Headshots and Portraits With Peter Hurley!"
Great job Mark. One caveat of high speed sync is that in order for the flash to fire multiple times it doesn't have time to provide a single "full-power" flash thereby clipping the flash curve which can sometimes impact the color. Most flash manufacturers don't recommend high speed sync if accurate color is required. Also, because you're not getting the full flash power, you usually need to move your flash closer to the subject.
Mark Astmann