The same but different
Being primarily a studio photographer, I haven't spent a lot of time looking at High Speed Sync and no time looking at HyperSync (because I didn't see the need to purchase yet another trigger system). But that changed this week. No, I didn't start working outdoors--we seem to have gone from summer directly to winter here in Seattle. But I was browsing through eBay and saw a PocketWizard MiniTT1 trigger for $30 and it made me start to think about HyperSync. Later that same day I stopped in a camera shop and they had a used MiniTT1 on sale for $19. The universe must be telling me something--I bought the trigger.
High Speed Sync (HSS) and HyperSync do a similar thing, yet are very different. Both allow you to make photographs using shutter speeds faster than the usual sync speed of your camera. You might ask, "why would I want to do this?" The main reason for this is to work outdoors with your flash balancing exposure with the ambient sunlight.
High Speed Sync
HSS has been around for a while in camera speed lights. Its main claim to fame is that with it you are able to make flash photographs outdoors at wide open apertures to allow shallow depth of field with a very soft and creamy out of focus background. Normally, balancing the flash with the sun will yield apertures around f/11 or so because the highest shutter speed you can use with your flash is around 1/200 of a second. We can see where that comes from by using the Sunny 16 rule. In full sun, the exposure for your photo will be approximately 1/ISO shutter speed at f/16. If your ISO is 100, that will be 1/100 second at f/16 or 1/200 second at f/11. If you are happy with f/11 you just set your flash power to give the same f/11 reading. But what if you want to be at f/4 to have a more shallow depth of field? Or if you want to raise your shutter speed to make the ambient light exposure darker to help make your subject stand out from the background? If you raise your shutter speed to darken the background it won't sync. If you open up the lens to f/4 for less depth of field and leave the shutter speed at 1/200 (flash sync speed) you have a totally blown out photo from the ambient sunlight. To bring the ambient exposure back to normal you need to speed up your shutter speed. Let's look at the equivalent exposures for 1/200 @ f/11:
1/200 @ f/11
1/400 @ f/8
1/800 @ f/5.6
1/1600 @ f/4
At the shutter speeds faster than the sync speed the flash is not going to register in the image. The flash will not sync with the shutter, so the image will be the same with or without the flash firing.
Enter High Speed Sync!
HSS, as mentioned above, is a feature available in many speed lights and is now available in a number of newer studio flashes (such as the Interfit S1). What HSS does is to fire the flash stroboscopically (pop pop pop pop pop pop pop) as the shutter curtains move in the camera to allow the flash to register in the image. As you are probably well aware, most flashes require a recycle time between pops of the flash. Recycle time ranges from 6 seconds on some speed lights down to less than a second on some high end studio lights. But we need a bunch of pops to occur within 1/4000 of a second. That isn't possible at full power with any of the flash units (well, maybe in some of the $10,000 + Profoto and Broncolor systems). So HSS fires the flash rapidly at a very low power output to that it doesn't need any recycle time. That takes care of two issues. The flash is synced with the high shutter speed and the power is reduced to allow you to work at f/4 or wider. However, the power is so reduced that if you are using a modifier like a soft box on your flash the light has to be in very close to your subject. If you are doing more than a head and shoulders portrait the light will most likely be in your frame and need to be removed via retouching in post. If you need a darker background you raise your shutter speed, but you loose more and more power from the flash (approximately 1 stop per full step change in shutter speed). Other disadvantages of HSS are that it goes through batteries quicker and will shorten the lifespan of your flash tube. But it does what it does when you need what it does.
So, what is HyperSync?
HyperSync is something that comes to us from the PocketWizard company. PocketWizard is a brand of radio remote triggers that has been around for a number of years. A few years ago they came out with a set of transmitters (MiniTT1) and transceivers (FlexTT5) that can be programmed to time the firing of your flash with the shutter in your camera to allow a full power flash to sync at higher shutter speeds. At first it sounds too good to be true. And it sort of is. Yes, you get the flash to register in the image, but the exposure is not consistent across the frame. In most situations I think you will find yourself having to do a bit of post-production to even out the light in the image. Better than having no image at all, though.
Let's look at some examples of photographs taken with my Speedotron 2400 watt second power pack and a Canon 6D camera at 1/800 second shutter speed. I picked this flash unit because it has a long duration flash that I figured would work better with HyperSync than a flash with a fast duration.
The first image was made using a standard Pocket Wizard Plus III trigger and a MultiMax receiver. ISO 100 at f/11. As you can see the flash only registered a small sliver at the top of the frame. Exactly what would be expected at 1/800 second. The next image was made with everything the same except for the trigger on the camera, which was changed out to the MiniTT1. You can see that the flash registered, but the image is darker at the top than at the bottom. The third image shows what it looks like after applying a graduated filter in Adobe Photoshop Lightroom to brighten up the top part of the photo. Not perfect. But with a bit more processing it could be usable and much better than not getting an image at all. For reference, the final image was made with the standard trigger and at 1/125 second and f/22 as it came out of the camera with no adjustments.
Outdoors, where HyperSync is supposed to be used (if the weather gets nice I'll update this with outdoor images) the inconsistency in the exposure might not be as noticeable because the ambient sunlight will fill in some of the shadows. And like HSS, it will allow you to use higher shutter speeds to darken the background. At this point, I don't really see any need or use for HyperSync in the studio.
In the studio
HSS, on the other hand, does have a place in the studio. With most studio lights even at their lowest power settings with the light in close to your subject you will be getting f/5.6 or so. By enabling HSS and working at fast shutter speeds around 1/2400 or 1/3200 the flash power will be reduced enough to let you work at f/1.4 if desired. These two images made at Russell Brown's pre-conference event at Adobe MAX 2017 and show the difference between working at f/4.0 and f/1.4. The HSS option on the Interfit S1 strobe (with a 2x3-foot softbox) that I used here allowed me to open up the lens for the shallow depth of field making a different look between the photographs.