Nausicaa in Lanzarote - HSS Sync (Patreon)

In April, I did a private workshop with a UK photographer, with Nausicaa Yami as the model. The evening before, we had talked about High-Speed Sync, and I set up to make an image or two with that.

HSS (High-Speed Sync) is a bit counterintuitive: It’s the ability of a trigger to control the flash to have a flash duration that is slightly LONGER than the shutter speed.

Please think of the camera shutter as if it was two curtains (it is).

With shutter speeds up til about 1/200 sec, one curtain is opened from the left, and once fully open, the next curtain, also from the left, will start to close.

If you use flash, it should happen when the shutter is entirely open.

Usually, the flash duration is 1/1000 - 1/64.000 of a second.

Usually, you would use a 1/160 second as the shutter must be fully open when the flash fires so it can expose the entire frame.

If a faster speed is used, the shutter will only be partly open before the flash fires, and thus a portion of the frame will not receive light.

So when using a shutter speed faster than 1/200 sec, the one curtain is drawn open (from the left), but before it’s fully open, the next curtain from the left will start to close.

So regardless of how fast the flash output is, it can never expose the entire frame at a faster shutter speed.

When using HSS, the flash duration becomes LONGER:

So it starts before the first curtain opens and ends after the second curtain is closed.

The first and third image is shot with the flash, and incidentally at 1/2500 second, as you can see on the EXIF from photoshop.

One tell-tale is that the light on the model's head is brighter than her legs because of the falloff.

In the end, I just resorted to daylight, as seen in the other images.