Back in 2018 I did a shoot with Russell Finsterwald for Niner Bikes, and as usual I brought along a couple of speedlights and my Pocket Wizard radio triggers for them. At that time I was using the Nikon SB900's and using my own bastardized version of HyperSync with my Nikon D4. HyperSync or High Speed Sync (HSS) refers to different ways of syncing your flash with your camera at a speed above that of the camera's native sync speed, usually around 1/250th of a second.
The main issue with shooting action at 1/250th in bright daylight is you often end up with some blur on your subject. 1/250 simply isn't fast enough to freeze action. If you underexpose the ambient light on your subject a little bit and then use a short duration flash to completely light your subject you can make it work, but this usually requires an on camera or camera axis flash (which doesn't look great as there are no shadows) or several flashes powerful enough to beat the sunlight. I normally use at least three lights when I'm doing this kind of lighting, and in a brightly lit location they need to be powerful lights, which are heavy. By using HSS or HyperSync we can allow the camera's shutter speed to freeze the action, and just use the flash as a creative lighting tool.
High Speed Sync is something that camera manufacturers and some flash manufacturers have built in for more than a few years. It is a system where the camera sends a signal to flash to fire multiple times during the exposure to evenly light the image as the shutter moves across the frame. It was originally available only with on camera flash, but is now available for off camera flash (OCF) systems from many manufacturers. The flash has to fire multiple times in very quick succession so the flash power is greatly reduced.
HyperSync, or what Elinchrom calls Hi-Sync for their flash systems, is the process of firing one long duration flash slightly before the shutter opens. If the flash pulse is long enough and the shutter fast enough the flash pulse will cover the entire exposure. The main drawback to this system is that the light in a flash pulse is not consistent throughout it's duration, and you can have light fall off near the bottom of your frame. If you're lighting in a scene like this one that isn't really noticeable as the whole scene is evenly lit by daylight.
The normal flash sync trigger for your camera occurs once the shutter is fully open, however with HyperSync you need to fire the flash slightly before the shutter starts to open. This means that you need to know when the shutter is going to open before it happens. When you depress the shutter button there is always a slight delay before the image is taken, it may only be 1/1000 of a second or less, but there is always a delay. This is because there are things that need to happen before the image can be taken. With a DSLR camera the lens is always wide open when you're looking through the viewfinder. This gives you the brightest and best view possible while composing your shot. When you depress the shutter the lens stops down to the shooting aperture and the mirror lifts up before the shutter opens. With a mirrorless camera neither of these need to happen, but there is still the smallest of delays, especially when using TTL flash. If you're shooting any camera using TTL flash when you depress the shutter the camera fires several "monitor" preflashes and measures how it affects the scene to help determine the correct light output. This happens in a fraction of a second and is mostly unnoticeable. Then the camera opens the shutter and fires the flash at the predetermined output. The real importance of all of this info is simply that the camera knows when the shutter is about the open, before it actually happens. Pocket Wizard and Elinchrom both use this information to fire the flash very slightly before the shutter opens. The actual timing of it is adjustable using a programmable offset to improve the flash coverage in the image. One thing to keep in mind is that this works best with a long duration flash, the opposite of what you would normally use to try to freeze action. Elinchrom created a special long duration "HS" or high sync flash head for this, and if you're using speedlights it works best with the flash at full power.
I personally found that I didn't get as good of a light output using Pocket Wizard's built in HyperSync feature, I couldn't adjust the offset as far as I'd like. However I found that if I put a Pocket Wizard TTL transceiver on my camera it would automatically send a monitor preflash signal, and that would be sent through to the hotshoe on top of the transceiver as well. By putting a second Pocket Wizard transmitter on top of the first I could fire my flashes at the monitor preflash signal, and using my Nikon SB900's at full power I got better light coverage of the entire frame. Convoluted I know, and Pocket Wizard assured me that this wasn't possible and wasn't happening, but it actually worked well. That's what I used in this and many other images.
Shot with a Nikon D4 with a Pocket Wizard Mini TT1 unit on the hotshoe set to channel 20, and a Pocket Wizard MultiMAX on top of that set to transmit on channel 24. Both of the flashes were set at full 1/1 power and attached to Pocket Wizard TT5 units set to receive on channel 24 in normal non TTL mode. This was shot at 1/1250 at F/5.6 at 250 ISO.
Understanding how things work makes it a lot easier to accomplish new things. Are you interested in High Speed Sync and Hyper Sync (or Hi-Sync) and how they work? I'll be posting a far more in depth post with video in the upcoming months. Stay tuned for more!
Other photos from this shoot can be found here
