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 …
It would take a lot of time to assemble this from scratch every time, so Yishai keeps the four speedlights and four RadioPoppers connected with the FourSquare Block. Everything is then kept in a camera case. On a shoot then, the main unit is connected to a lightstand (via that red connecting handle), and the batteries attached. Elegant .. but if you add up the cost of this, it is spendy! But works very well.
The pull-back shot to show the position of the lightstand:
… and the shot with the flash disabled, so you can get a sense of what the available light looked like at the chosen settings of 1/8000 @ f2 @ 100 ISO
Another two pull-back shots showing the flash setup in relation to our model, with the flash firing, and one with the flash disabled.
Looking at that top image again though:
In using the four flashes like that without a diffuser, I saw that we got a double shadow in some images, depending on Angelique’s pose. Here is the 100% crop of the top image. You can see the double edge shadow there on her neck. Not that noticeable, but not ideal.
We then opted for adding a small shoot-through umbrella to diffuse the light a bit. This did cut down on the output, so I changed my settings to 1/4000 @ f2 @ 100 ISO to have the flash expose correctly. (This means we were close to the maximum output of the four speedlights.) The light was more even with the umbrella, and without that double shadow.
By bringing more ambient light in, the cityscape is less dramatically under-exposed, but the photograph still looks great.
This was an interesting solution to working with high-speed flash sync and overcoming the limitation of loss of effective power. To get to maximum flash sync speed at f2 with this light, I would’ve had to cut down on 5 stops of light. The neutral density filter that I normally use, wouldn’t have been enough, and a filter like the Singh-Ray Vari-ND (B&H), would’ve been necessary to cut the available light down by that much.
A big thank you to Yishai for letting me play with these toys, and a big thank you to Angelique who was so patient with us on this freezing cold day.
articles on the use of a ND filter
- Environmental portraits of a speedway racer
- Using a ND filter with flash to control DoF
- Using a ND filter with flash
recommended neutral density filters