15.5. Kill the ambient

As discussed in section 6.3, each flash exposure is essentially a double exposure—there's the subject lit by flash, and the background which may be lit by ambient light. In the case of night or other low-light conditions, it's fairly easy to reduce shutter times to minimize the amount of light contributed by ambient without affecting flash. But in daylight, this becomes trickier, because the X-sync limit puts an upper ceiling on the maximum attainable shutter speed.

Fortunately, the arrival of high-speed sync means that X-sync is no longer the barrier that it was. This makes it much easier to set high shutter speeds to keep ambient exposures low while exposing the foreground normally using flash. This technique can create moody atmospheres under what appear to be fairly uninteresting or banal lighting conditions.