Sony produced what could be described as a game-changer of a camera with its current flagship, the Sony a1. Although this camera offers a plethora of new features that most reviews have raved about. One of its most remarkable features has gone a little under the radar. This feature is the increase in the flash sync speed to 1/400th of a second shutter speed.
The Sony a1 is one of the best full-frame mirrorless cameras on the market. Not only can it shoot high-resolution 50-megapixel files, but it can also capture this much resolution at 30-frames per second. It was only up until recently that we thought speed and high resolution were an impossible combination, based on current technology. You could either have a high-resolution camera that captures a great amount of detail, or you could have a low-resolution camera that shoots extremely fast for those high-speed situations. Sony managed to do both in one camera.
Additionally, Sony also managed to cram in 8K 30p and 4K 120p in 4:2:2, 10-bit recording. Essentially, the Sony a1 is an incredible camera system. However, these features are obvious upgrades and inevitable in the grand scheme of things. Almost everyone expected Sony to produce an 8K capable camera system, however, I doubt that anyone thought Sony would improve the shutter mechanism and sync speed in the Sony a1.
What Is a Focal Plane Shutter?
A focal plane shutter is essentially the shutter mechanism found in almost all DSLR and mirrorless cameras. A focal plane shutter exists in the camera and sits in front of the camera sensor. There are two sections to a focal plane shutter and they are called the first curtain and second curtain.
The first curtain will drop open to reveal the full sensor after which point the second curtain will drop down to close the shutters again. The time it takes for the shutter to open and close depends on your shutter speed.
The main advantage of focal plane shutters is that they can manage faster shutter speeds than leaf shutter mechanisms (discussed below). Most high-end DSLR and mirrorless cameras can manage shutter speeds of up to 1/8000s, which is considerably faster than leaf shutter cameras.
The other advantage of focal plane shutters is that they operate within the camera. This means that virtually any kind of lens can be attached and the shutter mechanism can still fire. You can even use pinhole body caps on the camera and the shutter will still fire allowing you to expose an image.
The downside is that a focal plane shutter can only remain fully open up to a certain speed. For most cameras, this shutter speed is 1/200s. Above this speed, the shutter blades will no longer open fully as it moves down the sensor to expose the image. The opening in the shutter will become smaller as you increase the shutter speed. This is not a huge problem unless you're shooting with flash. If the opening in the shutter blades is smaller than the sensor, then the whole sensor will not be exposed when the flash is triggered.
As you can see in the comparison above, a large portion of the flash ends up hitting the shutter blades instead of the sensor when shooting faster than the sync speed. To resolve this, you can use a feature called high-speed-sync. In this mode, the flash will fire multiple times rapidly, in order to follow the shutter blades as they move along the sensor. Unfortunately, this feature considerably reduces the flash power making it less than ideal in many situations.
What Is a Leaf Shutter?
A leaf shutter is relatively rare when it comes to camera systems. The biggest and most obvious difference between a leaf shutter and a focal plane shutter is that the leaf shutter operates within the lens instead of the camera. This highly limits third-party compatibility. Another obvious difference is the structure of the leaf shutter.
Focal plane shutters move across the sensor in a single direction, generally top to bottom. Leaf shutters open and close in a circular motion that is somewhat similar to how aperture blades open and close. It's this design difference that makes the biggest difference. Unlike focal plane shutters, leaf shutter mechanisms do not have a flash sync speed limit. Leaf shutter lenses can synchronize with flash at any shutter speed it can manage.
For instance, current Hasselblad lenses can synchronize flash even at 1/2000s shutter speed without needing any kind of high-speed-sync mode. The downside with leaf shutters is that the highest speed currently available is 1/2000s, and this is considerably lower than what focal plane shutters can achieve, which is 1/8000s.
How Has Sony Managed This?
A camera shutter mechanism generally operates with a spring-loaded system. In a focal plane shutter camera, the two curtains are loaded and then fire when you press the shutter button. The spring-loaded system has worked extremely well in cameras for decades. However, this system hasn't been updated for a long time either.
In comes the Sony a1 with its dual-driven focal plane shutter. The shutter mechanism in this camera operates with a spring-loaded system and also a magnetic system. The spring-loaded system will be active for most shutter speeds fast and slow. The magnetic system is only active between shutter speeds of 1/320s and 1/400s.
These are the two fastest points that The Sony a1 can synchronize flash in full-frame mode. The magnetic system allows the shutter curtains to move faster across the frame. The first curtain can drop open fast enough that by the time the second curtain is ready to close, the full sensor is open for exposure.
This is the key difference. The magnetic system can move the shutter curtains faster than the standard mechanism. That extra speed helps ensure the full sensor is open for exposure as opposed to portions being blocked by the shutter blades.
Why This Is a Big Update
The Sony a1 is the only full-frame camera on the market right now that can synchronize with flash at 1/400th of a second shutter speed. This is double the speed of most full-frame cameras, including flagship systems from Canon and Nikon. This sync speed can increase further to 1/500s shutter if you shoot in APS-C mode. This kind of speed is on the same level as some leaf shutter lenses.
Interestingly, even with this higher sync speed in the Sony a1, the camera shutter is durable enough to manage more than 500,000 cycles. Although it's important to mention that Sony did not disclose the durability ratings for the shutter mechanism when flash sync priority is enabled.
Nonetheless, for many working photographers, this increase in the sync speed offers more of a real-world benefit than improvements to dynamic range or increases in resolution.
Having lots of resolution can be great, however, after a certain point, a few more pixels make very little difference to how you shoot and the results you produce. Even with dynamic range, most cameras now offer enough flexibility that an extra half stop doesn't make much or any difference to workflow. Features such as megapixels and dynamic range might make for great headlines, but in the grand scheme of things, it's just marketing. Even smartphones can now shoot up to 100 megapixels and higher.
The increase in sync speed makes a real change to workflow. You're able to shoot at a higher shutter speed regardless of what kind of flash you're using. You can also delay the need to shoot with high-speed sync by a full stop. This is especially useful when shooting in a controlled or studio-based environment.
For a long time, if you were shooting in a studio then the maximum shutter speed you could probably choose was 1/200s. Being able to shoot at a faster shutter speed in a controlled environment will very likely reduce potential issues. If you're photographing people for example, then introducing movement into the shots is less likely to result in motion blur.
This is without a doubt one of the best and most difficult to achieve leaps in technology we've seen in a long time, and Sony should be celebrated for doing this.
This is a huge leap forward for working professionals and the best thing is that it won't be too long before this feature starts appearing in less expensive cameras. As the cost of features becomes less expensive, we may start to see this become the standard synchronization speed for flash.
What's not clear at the moment is whether Sony can take this dual-driven mechanism further. It's arguably fair to assume that the magnetic system could probably manage even faster shutter speeds. However, it was probably durability concerns that capped the synchronization speed at 1/400s.
Hopefully, we're only at the beginning stages of what's possible with magnetic shutter drives. Who knows, the next flagship camera from Sony might even synchronize flash at 1/1000s.