The Flash Photography Field Guide

Advanced High-speed Sync

We’ve already seen how using Canon’s E-TTL and Nikon’s CLS system enables you to set a shutter speed higher than your camera’s designated sync speed. This is called “Auto FP” or High Speed Sync (HSS). The flash pulses many times during the exposure as the shutter opening moves its way up the frame of the sensor.

You can’t see the flash doing this—it’s far too quick. It does reduce the flash power hugely, and as it’s highly likely you’ll be using this technique outdoors on a sunny day when you need lots of power, it’s less than optimal. Added to that the issues around CLS or E-TTL using an infrared trigger system, and it can be unreliable.

There are other ways to achieve this, however. The first is to upgrade to the new ...