Sony produced what could be described as a revolutionary camera with its current flagship, the Sony a1. Although this camera offers a plethora of new features that most reviewers praised. One of its most notable features has flown a bit under the radar. This feature is the increase in 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 record high-resolution 50-megapixel files, but it can also capture that resolution at 30 frames per second. It wasn’t until recently that we thought speed and high resolution were an impossible combination, based on current technology. You can either have a high resolution camera that captures a great amount of detail or a low resolution camera that shoots extremely fast for those high speed situations. Sony has managed to do both in one camera.
Additionally, Sony has also managed to cram in 8K 30p and 4K 120p in 4:2:2, 10-bit recording. Essentially, the Sony a1 is an amazing camera system. However, these features are obvious and unavoidable upgrades in the grand scheme of things. Almost everyone expected Sony to produce an 8K capable camera system, however, I doubt anyone would think Sony would improve the Sony a1’s shutter mechanism and sync speed.
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 in a focal plane shutter and they are called the first curtain and the second curtain.
The first curtain will open to reveal the full sensor, after which the second curtain will lower to close the shutters. 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 handle faster shutter speeds than leaf shutter mechanisms (see below). Most high-end DSLR and mirrorless cameras can handle shutter speeds up to 1/8000s, which is considerably faster than leaf shutter cameras.
The other advantage of focal plane shutters is that they work inside the camera. This means that virtually any type 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 stay fully open up to a certain speed. For most cameras, this shutter speed is 1/200s. Above this speed, the shutter blades no longer fully open as it lowers the sensor to expose the image. The shutter opening narrows as you increase the shutter speed. Not a big deal unless you’re shooting with flash. If the aperture of the shutter blades is smaller than the sensor, the entire sensor will not be exposed to the flash firing.
As you can see in the comparison above, a lot of the flash ends up hitting the shutter blades instead of the sensor when shooting faster than sync speed. To solve this problem, you can use a feature called high-speed synchronization. In this mode, the flash fires several times quickly, in order to follow the shutter blades as they move along the sensor. Unfortunately, this feature significantly reduces flash output, making it less than ideal in many situations.
What is a swing 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 works in the lens instead of the camera. This severely limits compatibility with third parties. Another obvious difference is the structure of the hinged shutter.
Focal plane shutters move across the sensor in a single direction, usually up and down. Hinged shutters open and close in a circular motion which 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 have no flash sync speed limit. Leaf shutter lenses can sync with flash at any shutter speed it can handle.
For example, current Hasselblad lenses can sync flash even at a shutter speed of 1/2000s without the need for a high-speed sync mode. The disadvantage of leaf shutters is that the highest speed currently available is 1/2000s, which is considerably lower than what focal plane shutters can achieve, which is 1/8000s.
How did Sony handle this?
A camera shutter mechanism usually works with a spring system. In a focal plane shutter camera, both curtains are charged and then fire when you press the shutter button. The spring system has worked extremely well in cameras for decades. However, this system has not been updated for a long time either.
Enter the Sony a1 with its dual drive focal plane shutter. The shutter mechanism of this camera works with a spring system and also a magnetic system. The spring system will be active for most fast and slow shutter speeds. The magnetic system is only active between shutter speeds of 1/320s and 1/400s.
These are the fastest two points the Sony a1 can sync with flash in full frame mode. The magnetic system allows the shutter curtains to move faster across the frame. The first curtain can open fast enough that by the time the second curtain is ready to close, the full sensor is open for exposure.
This is the main difference. The magnetic system can move the shutter curtains faster than the standard mechanism. This extra speed helps ensure that the full sensor is open for exposure, as opposed to the parts blocked by the shutter blades.
Why this is a big update
The Sony a1 is currently the only full-frame camera on the market capable of synchronizing with flash at a shutter speed of 1/400th of a second. That’s double the speed of most full-frame cameras, including flagship systems from Canon and Nikon. This sync speed can further increase to 1/500s shutter speed if shooting in APS-C mode. This kind of speed is on par with some leaf shutter lenses.
Interestingly, even with this higher sync speed in the Sony a1, the camera shutter is durable enough to handle over 500,000 cycles. Although it’s worth mentioning that Sony hasn’t disclosed the durability ratings of the shutter mechanism when flash sync priority is enabled.
Still, for many professional photographers, this increase in sync speed offers more real benefits than improvements in dynamic range or increases in resolution.
Having a lot of resolution can be great, however, after a certain point a few more pixels make very little difference to the way 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 no difference to the workflow. Features like megapixels and dynamic range can make for great headlines, but in the grand scheme of things, that’s just marketing. Even smartphones can now shoot up to 100 megapixels and more.
The increase in synchronization speed brings a real change to the workflow. You can shoot at higher shutter speeds regardless of the type of flash you use. You can also delay the need to take photos by one point with High Speed Sync. This is especially useful when shooting in a controlled environment or studio.
For a long time, if you were shooting in the studio, 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 most likely reduce potential issues. If you’re photographing people, for example, introducing motion into the shots is less likely to result in motion blur.
It’s arguably one of the best and hardest-to-achieve technological advancements we’ve seen in a long time, and Sony should be celebrated for it.
Final Thoughts
It’s a huge leap forward for working professionals and the best thing is that it won’t be long before this feature starts showing up in cheaper cameras. As the cost of features gets cheaper, we might start to see this becoming the standard sync speed for flash.
What’s unclear at this time is whether Sony can take this dual-drive mechanism further. It’s probably fair to assume that the magnetic system could probably handle even faster shutter speeds. However, it was likely durability issues that capped the sync speed at 1/400s.
Hopefully, we’re just at the beginning of what’s possible with magnetic shutter motors. Who knows, Sony’s next flagship camera might even sync the flash to 1/1000s.
