high speed flash sync

when you’d use high-speed flash sync / Auto FP

Going to High-Speed Flash sync, ie, over maximum flash sync speed, comes with a penalty. So here’s a solid recipe for when it makes most sense to go to high-speed flash sync / Auto FP.

When you need
either
- shallow depth-of-field, or
- fast shutter speeds,
and
- you have the flash power to spare.

As mentioned in the tutorial on high-speed flash sync (HSS), there is a considerable loss of power in going into high-speed flash sync territory. So you wouldn’t immediately use HSS in very bright light if you are trying to over-power the sun with flash. While the higher shutter speeds brings the ambient exposure down, it brings the effective flash power down faster than it affects the ambient light. So the sweet spot will always be at maximum flash sync speed. Therefore, using HSS shouldn’t just be a default way of working flash.

With this image, the softbox was close enough to Aleona that we were able to get good flash exposure on her, even at a high shutter speed. However, we did remove the one baffle of the softbox.

Learn more inside…

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using multiple speedlights with high-speed flash sync

This photo of Angelique, our model, was taken at 1/8000 @ f2 @ 100 ISO. Yes, an eight-thousand-th of a second.  The accompanying wide aperture (with an ultra-wide angle lens), gives a unique look to the image. The shallow depth-of-field and high shutter speed are mutually dependent effects in shooting in bright light. Working with a fast shutter speed, brought us into high-speed flash sync (HSS) territory.

Do keep in mind that this shoot was more of a technical exercise to work through the settings and see how the flash behaves when working in bright light, and needing either a faster shutter speed or wider aperture. (Or both.)  In this case, we achieved shallower depth of field and a faster shutter speed. Obviously, in photographing a static model, the advantage of a faster shutter speed is lost. But when you do need the faster shutter speed, this is the solution.

With high-speed flash sync, there is a dramatic loss in effective power, as shown in this previous article. To overcome this, you need to work very close to your subject, or gang up a number of speedlights as a group.

Back to the sequence of images – I wanted to under-expose the city-scape and then use flash to highlight the model against the environment.  So the lighting had to enhance the look of the wide-aperture wide-angle lens. The lens was the beautiful Canon 24mm f1.4 II (B&H). The camera that I used is the classic Canon 5D.

My friend Yishai, of HD PhotoVideo, had shown me his permanent set-up which he uses whenever he has the need of high-speed flash.  His setup consists of four  Canon 580 EX ii speedlights (B&H), held together via a Lightware Foursquare Block. To free himself up from line-of-sight restrictions, and give reliable control of these speedlights, Yishai had connected each speedlight to a RadioPopper PX unit. (They worked with perfect reliability during this shoot.)  To have the speedlights recycle fast enough, they are powered by two Quantum 2×2 batteries (B&H). By ganging up four speedlights like this, we can start overcoming the loss of flash power when going into HSS.

To show me how these work on an actual shoot, we arranged to meet up with Angelique (on this icy cold day) on this pier in Brooklyn, for a photo session. Here is what this setup looks like …

Learn more inside…

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