If you’re an old dog like me, sometimes new tricks pose a bit of a challenge. Take flash photography, for instance. We Gen-Xers remember a time when using a strobe with our DSLRs required dialing down the shutter speed to 1/125th or, if we’re lucky, 1/160th. But that limitation has long been removed thanks to high-speed sync (HSS). It’s a technological advancement that rewrites how flash can be used—particularly when photographing outdoors in daylight. It’s time we adjust our thinking to understand how high-speed sync can be better put to use.
Many speedlight-style flashes, mirrorless cameras and DSLRs are high-speed sync capable. Some studio-style strobes also include HSS functionality, though they typically require a dedicated transceiver mounted to the camera’s hot-shoe in order to ensure the timing works correctly. While most strobe manufacturers offer their own proprietary hot-shoe transmitters, they tend to be quite pricey. Godox, however, offers the series of X1 wireless transmitters that are high-speed-sync capable and quite affordable at less than $50. You just have to be sure to purchase the right model for your camera brand: N for Nikon, S for Sony, C for Canon.
High-speed sync solves the problem of fast shutter speeds not traditionally working with flash by firing the flash several times in rapid succession (though it may look like a single flash to the naked eye). The effect is that the duration of the flash is significantly extended so the light is on the entire duration of the sensor being exposed.
Setting up high-speed sync is different with every camera and flash, but in general, you’re going to find a high-speed setting in the flash or camera menu and enable it. Then it’s as easy as setting the exposure to whatever shutter speed you’d like (or even using an auto exposure mode such as aperture priority without concern that the shutter speed might surpass the flash sync speed). On my Sony A7R3, mounting an HSS-capable Sony flash means I can simply dial up the shutter speed and the flash will automatically switch to HSS mode.
The real question is why might you want to use high-speed flash sync?
When we talk about high speed, we might be tempted to think of sports or athletes or other fast-moving action. But in fact, it’s not typically the sports photographers who rely on high-speed sync so much as portrait photographers–particularly those who want to minimize background distractions by shooting with wide apertures even outdoors in sunlight.
One of the most common practices in portrait photography is shooting at a wide aperture in order to produce shallow depth of field to better isolate the subject against a blurry background. In direct, bright sunlight, shooting at ƒ/2 even at ISO 50 necessitates a shutter speed easily 1/1000th of a second or faster. For this reason, flash has traditionally not been usable when shooting natural light portraits at wide apertures because a traditional flash won’t sync with such a fast shutter speed.
Another use for flash in daylight situations is to “overpower the sun.” In these scenarios, photographers traditionally dial in an exposure setting that produces a stop or more of ambient underexposure (say, 1/125th at ƒ/22 at ISO 100) and then added strobe to create the key light in the scene. If you’ve ever seen a photograph clearly made outdoors during daytime where the sky is darker than normal, you’ve likely seen a photographer using flash to “overpower the sun.” The trouble is this approach traditionally required small apertures (such as ƒ/16, ƒ/22 and more), which produce tremendous depth of field, and which require powerful strobes capable of producing sufficient output to create an appropriate exposure at, say, ƒ/16.
High-speed sync changes that equation. Now instead of requiring a more powerful strobe, photographers can achieve ambient underexposure by increasing the shutter speed in lieu of the aperture. So an exposure setting of, say, 1/1000th at ƒ/4 might dramatically underexpose the ambient light while requiring less output from a strobe. This, too, makes high-speed sync an incredibly versatile lighting tool even when the subject isn’t moving fast.
High-speed sync opens up a world of wide-aperture options when shooting outdoors, but there are some downsides. Not the least of which being that high-speed sync reduces the effective guide number of the flash, which means it must be placed closer to the subject than usual. High-speed sync also draws more power, so you’ll deplete your flash’s batteries faster. If you’ll be on location using high-speed sync, you’d better plan to bring some backups.