Flash sync speed & high-speed sync (HSS)

Every camera has a fastest shutter speed it can use with flash — the sync speed, usually around 1/200s. Go faster and a black band creeps into the frame. High-speed sync (HSS) gets around it.

Recommended settings

Sync speed: ~1/160–1/250s (camera-dependent)

the fastest shutter where the whole frame is lit by the flash

Below sync speed: Normal flash

the sensor is fully open when the flash fires

Above sync speed: Turn on HSS

lets you use fast shutters / wide apertures in bright light

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Why it works

Above the sync speed the shutter never fully opens — it travels as a moving slit, so a single flash burst only lights part of the frame, leaving a black band. HSS solves this by pulsing the flash rapidly so it's lit for the slit's whole journey, at the cost of a lot of flash power and range.

Beginner tip

Indoors, just keep your shutter at or below the sync speed (e.g. 1/200s) and you'll never see the black band.

Going further

Use HSS outdoors when you want f/2 in bright sun for a blurred background — accept the reduced flash range it brings.

Common mistakes

Shooting flash at 1/1000s without HSS and getting a black band across the frame.
Expecting HSS to keep full flash power — it costs several stops of range.

FAQ

Why is there a black bar in my flash photos?

Your shutter speed is above the camera's sync speed, so the shutter wasn't fully open when the flash fired. Drop to the sync speed (around 1/200s) or enable high-speed sync.

What is high-speed sync (HSS)?

A flash mode that pulses the flash rapidly so it can be used above the normal sync speed — letting you use fast shutters and wide apertures in bright light.

Learn more

shutter speed mechanical vs electronic shutter