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 After gaining some experience in flash shooting, you can expand your shooting range even further and do some really creative shoots. You can try the high-speed sync feature. Let’s say you and your family are preparing to visit a nearby park with lots of beautiful flowers that mark the arrival of spring. You want to take several portraits of your lover and child, and use out-of-focus flowers as a background. Of course, your lover and child can’t get up early in the morning to take pictures, and you arrive at the park around 12:45 p.m.

Are you feeling too stressed? Your family has no idea about using light and photography, and explaining to them about shooting in the midday sun now won’t help. They just want you to hurry up and shoot. Then let’s get started, leaving the noon sun alone. Do you think a wedding photographer will tell the bride that she can’t take a picture of her outside in the garden because the midday sun is too bright? Definitely not.

This is when it is time to use the high-speed synchronization function. We know that to get the maximum brightness of the flash, it must be set to full power output, and the shutter speed cannot be higher than the maximum flash sync speed when shooting. But high-speed sync allows you to do flash photography at a much higher shutter speed than the highest flash sync speed. Since high-speed synchronization, wedding and portrait photographers around the world can use it to shoot in flower-filled gardens at midday.

You now need to take portraits of children in front of the garden from a distance of 9 meters. To make the flowers in the background sufficiently out of focus, you need to choose an aperture value of f/4. Because the surrounding light is very strong, the light meter recommends a shutter speed of 1/5000s. In addition, there is a strong light overhead that shines very stiffly on the subject’s face. But don’t worry, you can use an off-camera flash to fill in the subject’s face. Set the focal length to 105mm, framing the frame, all the elements in the viewfinder are perfect. You’re almost ready, set the camera to high-speed sync mode, and then set the focal length of the flash to 105mm as well. At exposure values of ISO 200, f/4, and 1/5000s, the flash distance table recommends a distance of 7 feet (2.13 meters) between the flash and the subject. Press the shutter button after placing the flash in place. You did, and you got a memorable, beautiful midday portrait. You are so smart!

How can you suddenly shoot at a shutter speed that is much higher than the maximum flash sync speed? This is mainly because the flash has a special function. Typically, when shooting at normal flash sync speed, the flash only emits one flash at a time. In high-speed sync mode, the flash emits a high-speed strobe that fires multiple times (literally hundreds of times per second). Due to the fast shutter speed, the camera closes shortly after the front curtain opens. When the narrow slit between the two curtains sweeps over the photosensitive element (or film) of a digital camera, the high-speed synchronous flash constantly illuminates the scene (like a strobe). Thanks to this pulsed light, the subject can be exposed to the flash even if the narrow gap between the curtains is small.

No doubt now that you know the usefulness of high-speed synchronization, you can use it for your own creative shoots. If you use a Nikon or Canon camera, you can always turn on the high-speed sync feature. This way, you can use it for flash photography whenever you need it. When high-speed sync is turned on, you can shoot with the flash at any time and at any shutter speed, without having to think about setting the camera’s flash sync speed. You might think, I don’t have to worry about anything else anymore, just shoot with my heart. This idea is theoretically sound, but I don’t recommend it. If you look at the data in the yellow box, you’ll notice that when you turn on high-speed sync mode, the flash index is automatically reduced by half. This wastes a lot of flash energy, especially if you don’t need to use high-speed synchronization. Let’s say you inadvertently change your shutter speed from 1/250s to 1/1000s. At a shutter speed of 1/250s, the flash index is 160, and at a shutter speed of 1/1000s, the flash index is reduced to 40. Accordingly, the subject should only be properly exposed at least 5 feet (1.5 meters) from the flash. If your flash is mounted on a camera and the subject is 15 feet (4.5 meters) away from you, the flash will not be able to illuminate the subject. High-speed sync is a fantastic feature that you might make mistakes if you keep it enabled when you take all your photos, so it’s best to turn it on when you need it and turn it off when you’re not using it.

With the flash and high-speed sync, we can shoot almost at any time. Even at noon, thanks to the high-speed synchronization, we were able to take very good photos.

Turn on high-speed synchronization

The Canon 580EX flash refers to the high-speed sync function as “high-speed sync,” while Nikon calls it “focal plane.” Before shooting, you must turn on the function to keep the flash in sync with the ultra-fast shutter speed. On Canon’s flash, you need to press a button (please refer to the flash manual for details). When using a Nikon flash, you need to open the camera’s menu, then select the Custom function, find the “Bracketing/Flash” option, and select the sync speed 1/320s option. When I set my Nikon D300s to a sync speed of 1/320s, an FP icon appears on the flash LCD display, indicating that the camera is already in high-speed sync mode.

Limitations of high-speed synchronization

Isn’t there no disadvantage to shooting synchronously at high speed? Of course not! High-speed sync shooting affects the output power of the flash. With high-speed sync, the flash emits many strobe beams at a very fast speed, each time with a low output power, so that shutter speeds of 1/8000s or higher can be used. The output power may be reduced to 1/2 or even to 1/4. If the shutter speed is increased by a factor of 4, the flash index is reduced by half. Here are some detailed data for you.

Do you really need to jot down these complex numerical relationships? No, you just have to look at the distance meter behind the flash, it will tell you everything. When syncing at high speed, the output power of the flash becomes smaller, and the flash needs to be closer to the subject to produce the same exposure as at full power output. So how close is that? Depends on shutter speed. The faster the shutter speed, the shorter the distance between the flash and the subject. Install the flash on the camera, turn on the camera and flash, then turn on the high-speed sync function, adjust the shutter speed after setting the aperture value and look at the distance meter, you will find that as the shutter speed increases, the distance reading displayed on the distance meter will become smaller and smaller.

In a photography class in Tampa, a port city and tourist attraction on Florida’s west coast, my students tried high-speed synchronized photography for the first time. Our model Deana jumped for us countless times during the shoot, because Deana was going to “fly” from left to right for us, so of course we wanted to freeze the action with a faster shutter speed. When I suggested that students use a shutter speed of 1/4000s, several students immediately asked me, “My fastest flash sync speed is only 1/200s, how can I shoot at 1/4000th shutter speed?” “All the students were using Canon’s 580EX II flash that day, but none of them knew that their flash supported high-speed sync.

I asked them to set the ISO to 200 and the shutter speed to 1/4000s, and told them to dose the intense backlit sky with an aperture value of f/5.6. The flash distance meter shows that the flash should be 4 feet (1.22 meters) away from the subject. I had students lie or crouch on the sand ready to shoot upwards. I made a mark on the sand about 4 feet (1.22 meters) from the students (the flash is mounted on the camera), which would be Deana’s starting point.

The photo below was taken without flash, using natural light entirely.

The photo in the image below was taken with flash combined with high-speed synchronization, and you can see the benefits of high-speed synchronization.

Nikon D300S, 12-24mm lens, 16mm focal length, ISO200, f/5.6, 1/4000s, Nikon SB-900 flash

Shooting outdoor subjects in backlight, how nice it would be if the subject could be perfectly lit by the flash while still recording the bright and powerful backlight! In fact, high-speed synchronization can help us achieve this. However, be aware that some flashes do not support this feature. When faced with the “impossible” task of exposing ambient light beyond the fastest flash sync speed range, we have another solution, which is to use a neutral density dimmer, or neutral mirror for short.

When I took this set of photos, I used a wide-angle lens to shoot from a very low angle. I place these tulips in the foreground with the camera pointing up to the midday sky and sun. The exposure value is set to ISO200, f/11, 1/2000s. A shutter speed of 1/2000s is not surprising, as the ultra-bright background heavily affects metering. I used this exposure value to record a perfect exposure of the sun and sky without flash, but the tulips looked too dark (1). But if I expose the tulips with an exposure value of f/11,1/60s, I make the sky seriously overexposed (2nd photo). I wanted to record the correct exposure of the flower with the sun and the sky at the same time, and I wanted to get a large depth of field, so I only had one choice: use flash to light the tulips, so that the exposure of the flowers is the same as the exposure of the sky and the sun. I did a quick calculation and under normal circumstances I couldn’t shoot with flash. Because for the sky and sun to be exposed normally, the exposure value needs to be set to f/11,1/2000s. For most cameras, a shutter speed of 1/2000s exceeds the fastest flash sync speed, unless a high-speed sync function or a neutral lens is used. This time I chose the latter.

Nikon D300, 14mm fisheye lens, ISO200, f/11, 1/2000s

Nikon D300, 14mm fisheye lens, ISO200, f/11, 1/60s

Nikon D300, 14mm fisheye lens, ISO200, 3-stop neutral mirror, f/11, 1/250s, Nikon SB-900 flash

When I attached the 3-stop ND lens to the lens, the light meter showed that the exposure value to the sun and the backlit sky was f/11,1/250s. The shutter speed of 1/250s is just within the normal flash sync speed range. I reduced the output power of the flash to 1/32, and the distance meter shows that at the aperture value of f/11, the flash is capable of covering a distance range of about 2 feet (0.61 meters). That’s fine for me because I shot with a fisheye lens and was hoping to get close to the tulips to get the perfect big picture. Also, because I was framing the picture vertically, I took the flash off the hot shoe and connected it to the camera with a cable, I held the flash 2 feet (0.61 meters) above the tulip with my hand and pressed the shutter button. In this way, I take a picture where all elements are perfectly exposed. All because I used a neutral mirror.