X-Sync

X-Sync (or flash synchronization speed) refers to the fastest shutter speed at which a camera can synchronize with a flash to illuminate the entire image sensor. In conventional focal-plane shutters, this is typically between 1/160 and 1/250 of a second, depending on the camera model. At faster shutter speeds, the shutter doesn't expose the entire sensor at once, but rather creates a moving slit that travels across the sensor—meaning the flash would only illuminate part of the image. Understanding X-Sync is crucial when using flash in bright conditions, as it limits the photographer's ability to use faster shutter speeds that would normally help control ambient light. Techniques to overcome this limitation include using high-speed sync (HSS) flash technology, which pulses the flash to cover the entire exposure, neutral density filters to reduce ambient light, or alternative shutter technologies like leaf shutters or electronic shutters that allow for faster sync speeds. X-Sync is particularly important in portrait photography when balancing flash with sunlight and in action photography where both flash and fast shutter speeds are desired.