What is High Speed Synchronization (HSS)?

IMPORTANT: This article applies only to specific products and/or operating systems. Check Applicable Products and Categories for details.

High-speed synchronization (HSS) is a function that allows the camera to use fast shutter speeds with an external flash. Cameras have a limited flash sync speed; this means the fastest shutter speed that can be used with a built-in flash is generally 1/160 to 1/250 second depending on the camera. However, an external flash with HSS allows the camera to adjust to applicable lighting by using higher shutter speeds on the camera.

Note: HSS cannot be used if the flash is set at an upward angle, such as when using it as a bounce flash. The flash should be facing forward when mounted on the camera to use the HSS feature.

In normal flash photography using a camera's built-in flash, the flash instantaneously illuminates the subject when the shutter is fully open. Therefore only shutter speeds up to 1/125-1/250 of a second can be synchronized with the flash.

A HSS flash operates by sending multiple bursts of light at high speed and with the shutter blades of the camera only partly open. This enables you to illuminate a scene similar to that of a built-in flash but with the flash synchronized to use the faster shutter speeds on the camera.

NOTES:

• Except for the ILCE-9M III, the HSS function features are activated on the flash and not within the camera,
  • Refer to your Help Guide for more details
• HSS functionality is not guaranteed with non-Sony flash units.
• Wireless HSS is possible using certain combinations of camera flashes.
• The high-speed flash recharge cycle takes about 5 seconds.

For additional information, refer to the Sony Alpha Camera Lighting Guide.