Here are the images from the live stream I did on Profoto’s Facebook page. We do this live stream every Wednesday at 17:00 Central European Time.

This episode was the seventh one and is also available on Youtube (https://youtu.be/3LUUNAJx7Qo).

https://youtube.com/watch?v=3LUUNAJx7Qo%3Frel%3D0
I went thru how HSS work, do’s and don’ts with HSS and Boost.

First, here is the animation of how the curtains move at flash sync speed when the whole sensor gets exposed to light at the same time vs 1/4000 when the curtains move at same time and only a thin part of the sensor is exposed to light.

Here are the images of a fan showing how HSS does NOT freeze motion and how a single flash can freeze motion.

This image was taken in ambient light of a stationary fan. Settings were: Aperture: f3.5, Shutter speed: 1/125, Iso: 250

This image was taken in ambient light of a moving fan. Settings were: Aperture: f3.5, Shutter speed: 1/125, Iso: 250

This image was taken in ambient light of a moving fan. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 5000

This image was taken HSS of a moving fan. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 160, flash power 8.7

This image was taken normal flash of a moving fan. Settings were: Aperture: f2.8, Shutter speed: 1/125, Iso: 160, flash power 2.0

So, don’t use HSS to freeze motion. It’s the shutter speed that freezes motion and not the HSS flash. A single flash on the other hand can freeze motion much better than a fast shutter speed, no matter what flash you use.

Here’s a graph showing a regular flash in yellow, A1 HSS in red and the A1 HSS Boost in blue. You can see that the yellow regular flash is much shorter in time compared to HSS. You also see that the A1 HSS Boost (blue) gives four times more light compared to regular HSS (red).

Now, lets move outside and shoot in bright sunshine. First session with the sun in the back of the subject.

This image was taken in ambient light exposed for the face but the sky is burnt out. Settings were: Aperture: f2.8, Shutter speed: 1/800, Iso: 100

This image was taken in ambient light exposed for the sky but then the face is too dark. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 100

This image was taken with flash at sync speed so I had to close the aperture to f14 so now the background is sharper. Settings were: Aperture: f2.8, Shutter speed: 1/200, Iso: 100, flash power 8.0

This image was taken with flash HSS so I can open the aperture to f2.8 to get the background blurry. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 100, flash power 10.0

Now I’ve turned so the sun is shining on the face of the subject.

This image was taken in ambient light exposed for the sky. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 100

This image was taken with flash HSS and the flash is lightening up the shadows. Settings were: Aperture: f2.8, Shutter speed: 1/8000, Iso: 100, flash power 10.0

This image was taken with flash HSS Boost and the flash is lightening up the shadows even more. Settings were: Aperture: f2.8, Shutter speed: 1/8000, Iso: 100, flash power 10.0

Now back indoors to black out the background with HSS.

This image was taken in ambient light. Settings were: Aperture: f2.8, Shutter speed: 1/125, Iso: 2000

This image was taken with flash HSS. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 100, flash power 10.0

This image was taken with flash HSS and a collapsible reflector to lighten up the shadows. Settings were: Aperture: f2.8, Shutter speed: 1/4000, Iso: 100, flash power 10.0

I hope this helps! Check out the Youtube clip (https://youtu.be/3LUUNAJx7Qo). Don’t hesitate to contact me if you have any questions or concerns.

/Anders