Advantages and Disadvantages of High Speed Sync

Photography Tips

This video from The Slanted Lens demonstrates a secret that pro photographers use often. This is a trick that most amateur photographer would pay handsomely to know—how to use strobes in high speed sync mode on location:

Normal sync mode does not allow you to use a fast shutter speed of say 1/1000 of a second, due to the flash sync limitations of most cameras. High speed sync, however, allows you to do just that. With such high shutter speeds, you can shoot with a wide open aperture, get nice, soft shallow depth of field. To top it all you can bring the strobes into effect to create a nice highlight on the subject’s face.

Shutter speed controls the ambient light. A faster shutter speed will make the background appear dark. Aperture controls the depth of field and is also the primary connecting point with the strobe. Meaning, aperture should match the power output of the strobe.

Advantages of High Speed Sync

Normal Flash Sync

The camera shutter is actually a composite of two shutter curtains. The first one travels across the sensor and stops. As the shutter closes, the second curtain starts to travel. In between there is a clear window. This happens at slow shutter speeds. This gives ample opportunity for a flash to fire in between when the first curtain stops moving and the second curtain starts moving.

At faster shutter speeds, the second curtain starts moving even before the first has finished reaching the other end. So, for all conceivable purposes, only a small opening travels across the sensor. In other words, there is no clear window through which an exposure can be made in one instant when the flash fires. This is why in most high shutter speed situations, especially when using an off-camera flash in slave mode, you get a black band toward the bottom of the image.

High Speed Flash Sync

In the case of high speed sync, instead of firing a single high-intensity beam of light, a strobe fires rapid bursts of light over the course of the exposure, therefore eliminating the chances of black bands appearing in the photos.

Is There a Downside to Using High-Speed Sync?

Unfortunately, yes. With high speed sync, you lose about a stop of light from your strobes. Instead of spitting out one full power burst of light, it actually spits out more than a few over the course of the exposure. That takes a toll on the power. Some strobes tend to lose more power. Plus, you also drain out the batteries more quickly than in normal sync mode.

The rest of the video gives some interesting insight into the actual process of shooting, the lighting arrangement, and also the camera settings.