Understanding HyperSync and High Speed Sync

This section discusses HyperSync and High Speed Sync at a basic level. Read the HyperSync section for more detailed information on how to adjust HyperSync.

HyperSync and High Speed Sync both allow flash triggering with a camera at shutter speeds faster than X-sync. They function differently, however, and it is important to understand how X-Sync and High Speed Sync work to understand what is happening with HyperSync.

X-Sync

A flash directly connected to a camera

X-Sync is typically the fastest shutter speed at which your camera can trigger a flash. A camera triggering a flash at X-sync follows this time-line:

1. The camera is triggered by the photographer. Several milliseconds of Lag Time pass.
2. The first shutter opens, exposing the digital sensor. Some microseconds of time pass. This shutter will stay open for several milliseconds when the camera is set to X-Sync.
3. The camera triggers its PC terminal and hot shoe.
4. Some microseconds of time pass, then the flash begins to emit light.
5. The flash emits light for its Flash Duration. This can be any amount of time up to a few milliseconds.
6. The second shutter in the camera closes and both shutters reset.

Shutter speeds faster than X-Sync typically have the first and second shutters moving at the same time, or with no delay between the first shutter fully opening and the second shutter beginning to close. This does not work with normal flash triggering because the second shutter can be moving when the flash is generating light which yields a clipped exposure.

If your flash has a very long duration, or your shutter is very slow moving, you can get clipping even at X-sync.

A flash triggered remotely by a standard radio slave

Adding a standard radio slave to the above time line adds additional microseconds between steps 3 and 4. This additional delay moves the flash triggering moment towards the time when the second shutter will be moving. If your flash has a very long duration, or your shutter is very slow moving, you can get clipping when using a standard radio slave even at X-sync. You may have to use a slower shutter speed.

High Speed Sync

High Speed Sync (HSS), also known as Auto FP Sync, allows for triggering at shutter speeds faster than X-Sync.

"FP" stands for "Focal Plane." When the first shutter starts to open, it is exposing the digital sensor, which is the Focal Plane. FP Sync means triggering the flash just before the focal plane is exposed rather than waiting until shutter is fully open.

HSS uses a pulsed light technique that generates continuous light from before the first shutter begins to move until after the second shutter closes. At faster shutter speeds, both the first and second shutters are moving simultaneously, creating a moving slit across the digital sensor. Since the light appears continuous to the digital sensor, there is no clipping even at the fastest shutter speeds.

HSS requires a special flash like a Speedlite/Speedlight that can do the pulsed light technique. It also requires special timing information from the camera called pre-sync that is communicated through the TTL pins of a camera's hot shoe. A normal studio flash or standard non-TTL flash cannot perform the light pulse technique, nor does it have the electrical connections required to use the pre-sync information from the camera's TTL hot shoe pins.

An HSS time line would look like this:

1. The camera is triggered by the photographer. Several milliseconds of Lag Time pass.
2. Just before the first shutter would open, pre-sync occurs. This tells the Speedlight when to begin generating pulsed light as ...
3. The first shutter opens, exposing the digital sensor while the flash continuously pulses throughout the exposure.
4. Shortly after the first shutter moves, the second shutter begins to move. The pulsed light continues.
5. The second shutter in the camera closes and both shutters reset. The flash stops pulsing.

The pulsed light technique cannot emit as much light as a normal flash pulse as it uses a lot of energy to make the light continuous. This means that your flash must be much closer to the subject to be effective.

HyperSync

A normal flash is much more efficient at delivering light to a subject than an HSS or pulsed flash method. You can have your flash farther from a subject, or deliver more light to the scene when using a normal flash.

HyperSync uses the pre-sync information available in the TTL shoe pins to trigger a normal flash before X-Sync would occur. It does this by knowing how much time passes from pre-sync until X-sync. It can also eliminate the delay introduced by a radio slave.

HyperSync requires a ControlTL transmitter like the Nikon MiniTT1 and FlexTT5 or Canon MiniTT1 and FlexTT5. All HyperSync adjustments are made in the PocketWizard Utility on the Sync Timing Tab for the transmitting radio only. Any PocketWizard radio can be used as a receiver and be triggered from the ControlTL transmitter's HyperSync timing.

There are two methods of using HyperSync to get flash sync at faster than X-Sync shutter speeds, peak and tail. Most flashes generate a tall peak of light when first triggered, then that light fades down to a long tail. When adjusting the HyperSync slider you can optimize your HyperSync moment for the peak or for the tail with different results.

Using the Peak

The peak method uses the brightest peak of light generated by the flash.

Look at the X-Sync time line above. Steps 2 and 4 have some wasted time. Optimizing HyperSync to use the peak capitalizes on this wasted time. Moving the peak of light to a little bit before X-Sync can save enough time that you can use a shutter speed faster than X-Sync. As long as the second curtain is not yet moving when the flash is generating its peak of light, you will not get clipping.

Optimizing for the peak is effective for shutter speeds just faster than X-Sync, but not for the fastest shutter speeds of 1/640 and faster. Some camera and flash combinations can achieve up to 1/500 using this method, some only 1/250, before they encounter clipping at faster shutter speeds.

When adjusting HyperSync to work with the peak, you would be working with numbers closer to 0 (zero) on the HyperSync slider because you are only moving the peak of light a little way from X-Sync.

You need either:

• a very short peak flash duration so that the peak of light is finished before the second curtain begins to move.
• a very long peak flash duration so that the peak of light isn't changing when the second curtain is moving. It is not likely to find a flash with this kind of duration.

If you are using Speedlites as your flash source, you can optimize HyperSync for the shutter speeds just faster than X-Sync, then use the ControlTL system to switch over automatically to use HSS at shutter speeds where a normal flash would start to show clipping in the frame. See the Sync Timing Tab section in the PocketWizard Utility for information on setting "High Speed Sync (HSS/FP) Begins At:" for your ControlTL transmitter.

Using the Tail

The tail method uses the long tail of light generated after the peak is finished in a standard flash. This long tail is seen as continuous light for a shutter speed faster than X-Sync. Optimizing for the tail can often work for the fastest shutter speeds all the way up to 1/8000. This method delivers much less light to the camera's sensor than using the peak, but depending on your studio flash in use it can be substantially more than what is delivered by a Speedlight in HSS mode.

To use this method of HyperSync, you need to disable HSS in your ControlTL transmitter. See the Sync Timing Tab section in the PocketWizard Utility for information on setting "High Speed Sync (HSS/FP) Disable Mode." If you do not check this box for your transmitter, then you will not be able to trigger your remote studio flash at shutter speeds faster than "High Speed Sync (HSS/FP) Begins At:."

You optimize for the tail by adjusting the HyperSync slider to the left (more negative). This moves the peak of light such that it is completed before the first shutter starts to open. Then the flash will only be generating the long tail of light while the shutters are open. Depending on your flash's duration, it may be difficult to optimize for the shutter speeds closest to X-Sync as those require the longest flash duration.

This method is only effective with studio flash. Speedlites do not generate enough light during the tail to be more effective than using HSS would be.

Factors to consider

Read the HyperSync section for more detailed information on how to adjust HyperSync.

There are many factors that affect the success of HyperSync.

Flash duration is a critical factor. Flash duration often changes with power level. When you are fine-tuning HyperSync, make sure to test across the flash power levels you intend to use so you can see if certain flash durations will cause clipping at any shutter speed you intend to use.

There are many factors in a camera that affect HyperSync. Slower larger shutter blades will make HyperSync less likely to work near X-Sync with peak flash. Faster shutter blades, smaller sensors, or crop mode can often improve HyperSync success.

A large sensor and fast shutter blade camera like a Canon 1D Mark III may be able to get peak HyperSync at faster shutter speeds like 1/500.

A large sensor, but slow shutter blade camera like the Canon 5D Mark II may only be able to get 1/320 before HSS must be used.

A small sensor camera like a Canon 50D may be able to get 1/400, even though it has a slower shutter.

Triggering a studio flash from the HSS trigger moment

If your FlexTT5 is set to receive on a ControlTL channel, you can trigger a remote studio flash connected to the P2 port right at the HSS trigger moment. This may yield an effect similar to using HyperSync optimized for the tail, but it is not true HyperSync because you can not fine tune the trigger moment.

See the HyperSync page for information on how to use your radios with HyperSync.

To use HyperSync with a studio flash triggered you must set your remote FlexTT5 to receive on a Standard channel.