What is Flash Sync Speed? Everything You Need to Know

This is a guide covering flash sync speed.

In this glossary definition you’ll learn about:

From the get-go, flash sync speed already sounds like a confusing term for photography. The explanation of this occurrence isn’t so simple in most articles and also needs some time to understand.

Let’s dive in.

flash sync speed

What is Flash Sync Speed?

The flash sync definition is often oversimplified as the fastest shutter speed that you can use along with the flash.

It’s how fast your sync speed can match your flash, especially when using cameras with a focal plane shutter. Most modern cameras will have two separate shutter blades that go across your camera’s sensor, effectively exposing it against the light.

Since both of these blades go across the camera’s film, it will prevent your flash from fully affecting the camera’s sensor.

The short blast of flash can only affect the camera sensor if it’s fully opened during this brief moment.

However, the system changes if you are shooting at a fast shutter speed. The shutters aren’t fully open. Instead of the shutter blades going across the sensor one by one, they instead “chase” each other.

This simultaneous movement of both of these blades will create a small opening/slit that looks similar to the light when scanning documents. This only allows a fraction of the image sensor to be revealed at any moment.

If you shoot at a high shutter speed but only use a flash that only fires once, the shutter will block a bit of it. Creating an unflattering dark line/band across your image.

speedlight on camera
Photo by Tom Pumford

What Does Flash Sync Mean?

Flash sync is a computer-controlled system that synchronizes your flash and shutter release. This allows the flash output to illuminate your subject at a specific time.

This will make the flash evenly expose the image sensor. The flash imitates constant light by flashing multiple times, rather than flashing once and resulting in an unevenly lit image.

The flash sync meaning is essentially how fast your shutter speed should be when compared to the flash. Every camera has its own limitations, for example:

  • The Nikon D610 has its max flash sync speed of 1/200 seconds
  • The Nikon 7200 has its max flash sync speed at 1/250

Most cameras will usually have their max flash sync speed at 1/200 seconds up to 1/350, but it’s most common at 1/200 and 1/250. Unless you have those old medium format cameras (Hasselblad, Fujifilm GFX 50R, Pentax 645Z, etc) that use a leaf shutter.

Photographers that own cameras with a leaf shutter will most likely use it in a studio or similar location.

Since the shutter is built into the lens and not your camera, it operates more like an aperture. The leaf shutter may not be as fast as its focal plane brother, but it can operate with flashes optimally and at higher shutter speeds.

All of the available shutter speeds can be used by the leaf shutter, from the common 1/200 seconds to the high 1/1600 second sync speed.

f stop aperture size

Why Flash Sync Speed Matters?

The flash sync speed truly matters if you are planning to shoot using a flash. Which is one of the things you are most likely to do if you shoot objects. It really makes sense if you connect it to the exposure triangle.

The moment you try to increase your shutter speed, you’ll realize that it tends to get darker each time. But, at the same time, it allows you to capture fast-moving objects or subjects that aren’t still.

Your aperture will also work in a similar way. The smaller your aperture is, (especially at f/5.6, f/8.0, f/16) the darker your ambient light becomes.

The exposure triangle will adjust the exposure of your scene’s ambient lighting. Using your flash won’t change the scene’s ambient light, it will merely add the brightness of your subjects.

Flash sync matters when using a flash, since there is a limit to your shutter speed when using a flash. That limit is generally called the camera’s native sync.

Flash sync speed matters even more if you’re shooting outdoors in bright conditions. High-speed sync is useful for situations where you want a shallower depth of field when using a flash outdoors.

So, let’s learn more about this high-speed sync that is commonly on your on-camera flash.

on camera flash
Photo by Paul Gaudriault

Do You Need High-Speed Sync Flash?

A high-speed sync flash is useful for situations where you want to use shutter speeds faster than your camera’s native flash sync speed.

This feature is highly beneficial for situations where you have an extremely bright background and a subject in the shade. So, it naturally became particularly useful for outdoor portrait photographers.

I also recommend using a wider aperture for this. The feature itself saves you time from using ND filters and going through all the hassle with it.

Remember the camera’s curtain/shutter mechanic I explained earlier in this article? Well, that is linked to how useful a high-speed sync flash is.

When a fast shutter speed is used, the curtain will follow each other, only allowing the image sensor to be exposed bit by bit. Using a high-speed sync flash, the flash will “pop” multiple times to properly expose the image sensor with the flash.

This is achieved by using a camera capable of high-speed flash sync and a dedicated flash. The rest of the job is just setting up your camera and flash appropriately.

Unfortunately, one of the drawbacks of a high-speed sync flash is its range. The more you increase your shutter speed, your flashes effective range will reduce significantly.

Professional photographers will often have multiple powerful light sources and power packs, some would also recommend beamers. You may want to bring additional lights depending on the setting, subject distance, and lighting conditions.

This feature will give you more artistic control over your images whether your camera is in automatic, manual, or aperture mode.

How Do You Sync Flash with Shutter Speed?

On most cameras, you can easily set your flash for a high sync speed by going to the custom settings menu.

Search for the bracketing/flash, and you’ll be greeted with various options of flash sync speeds. Choose your desired flash speed, which will either be 1/200, 1/250, or 1/320 seconds depending on your camera’s native sync speed.

This will not make your camera and flash strictly synchronized in the selected sync speed. It actually means that both your camera and flash will sync at any shutter speed that your camera offers.

These are the basics, which usually apply to most cameras. But just to be sure, please check your camera’s instructions.

Some cameras such as the D700 and higher Speedlights offer high-speed sync.

Lastly, to confirm your chosen flash sync speed, there’ll be the letters FP on your Speedlights LCD. These letters indicate that your camera and flash are both in HSS mode.

camera backend
Photo by Sergio Rodriguez – Portugues del Olmo

What Happens When You Use a Shutter Speed Faster Than Sync Speed?

Black bands are the result of your shutter curtain blocking a part of the image during the exposure. This is what happens when you use shutter speeds higher than the sync speed.

A studio strobe/flash is instantaneous, which instantly makes the image brighter. Sadly this is only useful if your shutter speed is under 1/200 seconds. If your shutter curtain isn’t fully opened when the strobe flashes, you’ll get these unflattering, weird, and annoying black bands.

These bands are the main reason sync speed is used, which is why photographers tend to shoot below or at the flashes sync speed.

Using a slower shutter speed usually won’t matter to the exposure if you’re using a flash. The ambient light will become so low that it just doesn’t register.

Unless, if you make it too slow, like a second or longer. Shutter speeds that last longer than one second will definitely affect how your photos look. Either it is from the changes of the white balance or the ambient light taken in from the sources of light.

Maybe a little fun fact too. Have you ever wondered why these black bands start appearing from the bottom and climb up if the shutter is actually moving from top to bottom?

This problem is linked to how your image is actually upside down and backward. When the image hits your sensor or film, you will view it from the right side up, and the correct way around. All thanks to your camera’s built-in prism.

Luckily, once you experience this little black band incident you’ll likely never repeat it again in the future.

Final Remarks

Let me wrap up today’s topic:

  • So, what is flash sync speed? It’s the speed where both your camera and flash speed can work in tandem to produce an evenly exposed image.
  • Medium format cameras such as the Hasselblad won’t face this issue since their shutter system is inside their camera. This allows the camera to have a flash sync speed up to 1/1600.
  • Flash sync meaning is basically the limits of your camera’s native shutter speed can work with your strobe/Speedlight. Without a properly set flash sync, you’re likely to have black bands on the bottom of your image.
  • Flash speed matters the most when photographing outdoors and especially when the sun is quite bright. By adjusting your flash sync speed, you can easily take images that aren’t overexposed easily. All without needing to fiddle and refocus your camera with the ND Filters.
  • A high sync-speed flash only matters if you’re shooting with a flash (obviously). However, they are particularly useful when you have your subject in the shade but at the same time have a very bright background.
  • You can easily set up the flash by going to the custom settings menu, select bracketing/flash, and simply select the desired flash sync speed. It varies between models, but the maximum would probably be 1/200, 1/250, or 1/320 seconds.
  • Since fast shutter speeds make your shutter curtain move simultaneously, it creates a little gap between themselves for light to enter. If the image sensor isn’t evenly lit during this moment by multiple flashes, then the black bands will appear.
  • You can easily prevent these black bands by using a slower shutter speed or using a camera capable of high sync speed flash.

That’s pretty much it! The concept may be hard to digest at first, but it gets easier once you know how the shutter curtain works. HSS flash is particularly useful for outdoor photographers that shoot in bright environments. Keep practicing and good luck!

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