Why Do We Need HSS for Flash Photography?

One of the most useful features for flash photographers is high-speed sync, which allows us to use flash at essentially any shutter speed we would like. This excellent video shows how a focal-plane shutter works and why that creates the need for solutions like high-speed sync.

Coming to you from Andrew Boey with Beyond Photography, this excellent video will show you why high-speed sync (HSS) is needed for flash photography. High-speed sync (and similar technologies) are necessary because of the fundamental limitations of a focal-plane shutter, which works by drawing two separate mechanical curtains across the sensor — the first to begin the exposure and the second to finish it. After a certain shutter speed, there is not a time during which the entire sensor is exposed simultaneously, which means the essentially instantaneous pop of the flash cannot illuminate the entire sensor area, thus the need for high-speed sync. HSS has a few of its own drawbacks, such as loss of power or slightly uneven exposures, but overall, it is a fantastic solution for a lot of situations. Check out the video above for the full rundown.

If you would like to really dive into learning lighting, be sure to check out "Illuminating The Face: Lighting for Headshots and Portraits With Peter Hurley!"

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10 Comments

Rick Rizza's picture

I like to use continuous light. That has 1MHz switching power supply and > 100kHz PWM LED intensity control so even with 1/8000, still no flicker or partial exposure.

Billy Paul's picture

I like to use flash. For a similar sized battery/power supply I get around 10 stops more light.

Rick Rizza's picture

I can't disagree with this, if portability your looking for, then flash is the answer.

Benoit Pigeon's picture

I'm not familiar with LED and would have liked you to show some brands or anything I could search and check.

Rick Rizza's picture

To be honest, I used a cheap crap Neewer RGB LED. Never used it in 1/8000 though because I prefer lower ISO.The performance was good, they even have a softbox accessory sold separately. The apps is suck but you can do everything on the unit itself.

Andrew Eaton's picture

HSS chews flash battery and reduces flash max output to extend the flash duration... Leaf shutter lenses can sync to around 1/1000 to 1/2000 of a sec

Benoit Pigeon's picture

Unlike HSS, HiSync will not reduce power output. Battery wise, the more intensely you will use your lights, of course the shortest your battery will produce the needed power. But what is your priority, limiting your work and save on batteries or pushing the capabilities of the equipment and bring extra batteries?

Billy Paul's picture

Rubbish video. Anyone who doesn't know what HSS is still doesn't after watching this.

Dieter B's picture

We DONT *need* HSS for flash photography, an ND filter is a good alternative depending on situation

https://fstoppers.com/education/should-you-use-hss-flash-or-nd-filter-50...

Benoit Pigeon's picture

Gavin always has good clips but he his also paid to sell stuff. I don't know how dark a 5 stops ND filter would look like in a view finder, but that could be a concern for me shooting with a human subject.