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 lot of new features that most of the reviews have praised. One of its most notable features has gone a bit unnoticed. This function is the increase of the flash sync speed to 1/400 of a second of the shutter speed.
The Sony a1 is one of the best full-frame mirrorless cameras on the market. Not only can it record 50 megapixel high resolution files, but it can also capture this resolution at 30 frames per second. Only until recently did we think that speed and high resolution were an impossible combination, based on current technology. You could have a high resolution camera that captures a lot 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 a single camera.
Additionally, Sony also managed to include 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 compatible camera system, however I doubt anyone thought Sony would improve the shutter mechanism and sync speed on the Sony a1.
What is a focal plane shutter?
A focal plane shutter is essentially the shutter mechanism found on almost all DSLR and mirrorless cameras. There is a focal plane shutter on the camera and it is located in front of the camera sensor. There are two sections to 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 blinds again. The time it takes for the shutter to open and close depends on the shutter speed.
The main advantage of focal plane shutters is that they can handle faster shutter speeds than leaf shutter mechanisms (discussed below). Most high-end mirrorless and DSLR cameras can manage shutter speeds up to 1/8000 sec, 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 1/200 sec. Above this speed, the shutter blades will no longer fully open as the sensor lowers to expose the image. The shutter opening will get smaller as the shutter speed increases. This is not a big deal unless you are shooting with flash. If the aperture of the shutter blades is smaller than the sensor, then the entire sensor will not be exposed when the flash fires.
As you can see from the comparison above, a lot of the flash ends up hitting the shutter blades instead of the sensor when firing faster than the sync speed. To resolve this, you can use a feature called high-speed sync. In this mode, the flash will fire several times quickly to follow the shutter blades as they move across the sensor. Unfortunately, this feature greatly reduces the power of the flash, 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 inside the lens instead of the camera. This greatly limits compatibility with third parties. Another obvious difference is the structure of the shutter.
Focal plane shutters move across the sensor in only one direction, usually from top to bottom. Sash blinds open and close in a circular motion which is somewhat similar to how opening sashes open and close. It is 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 be flash synced at any shutter speed you can manage.
For example, current Hasselblad lenses can sync flash even at a shutter speed of 1/2000s without the need for any kind of high-speed sync mode. The downside of 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 achieved this?
A camera’s shutter mechanism is usually powered by a spring-loaded system. On a camera with a focal plane shutter, the two curtains charge up and then fire when you press the shutter button. The spring system has worked extremely well in cameras for decades. However, this system has also not been updated for a long time.
The Sony a1 arrives with its dual action focal plane shutter. The shutter mechanism of this camera works with a spring system and also with a magnetic system. The spring 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 fastest two points the Sony a1 can sync flash in full-frame mode. The magnetic system allows the shades of the blind to move faster through the frame. The first curtain can open fast enough that when the second curtain is ready to close, the entire sensor is open for exposure.
This is the key difference. The magnetic system can move the shades faster than the standard mechanism. That extra speed helps ensure the entire sensor is open for exposure rather than parts being blocked by shutter blades.
Why this is a great update
The Sony a1 is the only full-frame camera on the market right now that can sync with the flash at a shutter speed of 1/400 of a second. This is twice the speed of most full-frame cameras, including flagship systems from Canon and Nikon. This sync speed can be further increased 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 on the Sony a1, the camera’s shutter is durable enough to handle over 500,000 cycles. Although it is important to mention that Sony did not reveal the durability ratings of the shutter mechanism when flash sync priority is enabled.
For many working photographers, however, this increase in sync speed offers more real-world 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 it produces. Even with dynamic range, most cameras now offer enough flexibility that an extra half-stop doesn’t make much or any difference to your workflow. Features like megapixels and dynamic range might make great headlines, but in the grand scheme of things, it’s just marketing. Even smartphones can now shoot up to 100 megapixels and more.
The increase in sync speed is a real change in workflow. You can shoot at a higher shutter speed regardless of the type of flash you’re using. You can also delay the need for high-speed sync shooting with a dot. This is especially useful when shooting in a controlled or studio-based environment.
For a long time, if you were shooting in a studio, the maximum shutter speed you could probably choose was 1/200 sec. Being able to shoot at a faster shutter speed in a controlled environment will most likely reduce potential problems. If you’re photographing people, for example, introducing motion into your shots is less likely to result in motion blur.
Without a doubt, this is one of the best and most difficult technological advances we’ve seen in a long time, and we should celebrate Sony for doing it.
This is a huge step forward for working professionals and the best part is that it won’t be long before this feature starts showing up on less expensive cameras. As the cost of features becomes cheaper, we may start to see it become the standard sync speed for flash.
What’s unclear at this point is whether Sony can take this dual-drive mechanism any further. It’s arguably fair to assume that the magnetic system could probably handle even faster shutter speeds. However, it was probably durability issues that limited the sync speed to 1/400s.
Hopefully we are only in the beginning stages of what is possible with magnetic shutter units. Who knows, Sony’s next flagship camera might even sync flash at 1/1000s.