5 ms·

> Global shutter is a method of ending an exposure where all the image data is captured simultaneously. This is distinct from most existing shutter systems (ele

> Global shutter is a method of ending an exposure where all the image data is captured simultaneously. This is distinct from most existing shutter systems (electronic and mechanical) that start and end progressively: working their way across the sensor. Buried at the bottom of the article. This is interesting for especially video and sports photography. Some cameras with slower sensors suffer from the rolling shutter effect where fast moving subjects get distorted because the subject or the camera is moving. Think e.g. lampposts looking diagonal when shot from a fast moving car. Capturing all the pixels in one go solves that. Cropping the sensor is a common way to counter rolling shutter with current cameras. Basically, that means you are not using all of the pixels on the sensor and capture a smaller area. Aside from the quality, this also means that you don't use everything the lens captured; it's cropped away. So, it looks like you are using a larger focal length than you actually are and you can't capture at the full width of the lens. Lots of cameras use cropping to support higher resolutions and frame rates because they can't read out the sensor fast enough. This new sensor can use the full resolution and doesn't have to crop. And like with photography, you use shutter speed and aperture to control what the video looks like. 1/30th of a second is actually a relatively long exposure for a photo. And that's also potentially a lot of rolling shutter to deal with. An instant and fast readout means you have more wiggle room to play with this creatively or shoot in very bright or low light.

fullspectrumdev 3y ago
Thanks for the explainer - I was wondering what the significance was, and something I do is mess about with cameras for fun.
cubefox 3y ago
The article also mentions the downside of global shutter: lower dynamic range.
- codeconscious 3y ago
  Thank you, as I might have overlooked this downside had it not been for this comment. The article doesn't make this immediately clear: > It's a 24.6MP camera that Sony says doesn't compromise on ISO performance or dynamic range. Then later: > This might explain the base ISO of 250, which will ultimately limit the camera's maximum dynamic range. Sounds like a compromise to me...
Espressosaurus 3y ago
Not just the global shutter, but 120 FPS with full AF and AE is huge too. The A9III is going to be the best sports camera out there for a few years I think. Of course, you're going to pay through the nose if you want access to that tech. I can't wait for them to gain back the dynamic range and for it to roll down to less expensive cameras in the future.
clan 3y ago
Agreed. Worth mentioning as well: flash sync speed. As you are not dealing with a shutter or progressive capture this will be a thing of the past.
dheera 3y ago
> Cropping the sensor is a common way to counter rolling shutter with current camera Not in my experience. For full-frame 35mm digital cameras, the most common way to counter electronic rolling shutter effects is, ironically, a very fast mechanical shutter. In digital cameras with mechanical shutters, which include all Canon/Nikon/Sony/etc. consumer DSLRs and mirrorless cameras, the electronic shutter programmed to stay open for much longer than the mechanical shutter, which allows there to be a time instant when all pixels are simultaneously electronically open. The mechnical shutter then opens and closes during that time. The rolling shutter on a Sony a7 is about 26ms. Mechanical shutters can beat that easily, and can be as fast as <0.2ms. (Electronic shutters can be faster on a per-line basis. But they will still take 26ms to roll through the image for a rolling shutter sensor. So if your electronic shutter is set to 0.01ms you'll still be seeing 0.01ms exposures at each line but it will take 26ms to roll through the image.)
- Espressosaurus 3y ago
  Cropping is common in video. For stills, you're correct.
- mnw21cam 3y ago
  I don't think you're right about mechanical shutters being faster. The type of mechanical shutter on most cameras like this is a focal plane shutter[0]. It has two curtains - an upper one and a lower one. When the shutter is closed, the two overlap. For a long exposure (typically anything longer than 1/100s although some cameras are faster) the lower curtain will fall all the way, then the upper curtain will fall to close it off again. But at faster shutter speeds, the upper curtain will start falling before the lower curtain has reached the bottom, and so you can get exactly the same rolling shutter effect with a mechanical shutter as with an electronic shutter. For very fast shutter speeds, the exposure is a narrow slit between the two curtains that travels down the image at a much slower speed than the exposure time, and this is why most cameras can't synchronise with a flash at speeds faster than 1/100s or so. So therefore the type of mechanical shutter in most DSLRs and mirrorless cameras effectively have a rolling shutter transition time of 4-10ms, which is much more than the 0.2ms you claim. Video-specific cameras are where this might be improved, because you can have a shutter which is a rotating disc, and this can allow faster opening/closing times, because it doesn't need to speed up from a standstill for each frame. There exist central shutters which are mechanical shutters that act as a global shutter, but these are unusual because they need to be built into each lens you attach to the camera. These are typically limited to a maximum speed of 1/500s. [0] https://en.wikipedia.org/wiki/Focal-plane_shutter https://en.wikipedia.org/wiki/Focal-plane_shutter
vouaobrasil 3y ago
Most higher end cameras like the Panasonic G6, Nikon Z8/Z9, etc. hardly have any rolling shutter. You'll certainly NEVER see rolling shutter in any PRACTICAL application for video unless you pan like a true madman, either in photo or in video. (I am a professional photographer and videographer....) In fact for sports and wildlife, you'll NEVER see rolling shutter in pretty much any existing camera, either in photo or video. For photography it's been like this for decades and for videography recently. Where rolling shutter does appear is in the use of the electronic shutter only, but the Nikon Z9 already solved that, same with the Sony a1. The main benefit is flash sync and a very SLIGHT improvement in some types of distortion when shooting at very high shutter speeds. I'd argue that the Nikon Z9 is a much better camera if not wanting flash sync due to its lower base ISO. So to reiterate, the main benefit is not the reduction of rolling shutter, especially since any camera in this price point already has minimal rolling shutter. Global shutters are COOL, and the reduction of rolling shutter is COOL, but not the main point, though of course most future cameras will probably switch to global shutters at some point if the base ISO can be lowered.
- andrei_says_ 3y ago
  Global shutter allows for much higher flash sync speeds. I shoot dance, often in close proximity, and rolling shutter on canon r6 was a reason enough to upgrade to r6ii.
- onetimeuse92304 3y ago
  > I'd argue that the Nikon Z9 is a much better camera if not wanting flash sync due to its lower base ISO. Yeah. I think a lot of people focus too much on those "high end" specs and too little about small, practical, quality of life things. I remember how I instantly liked Fuji X100 for its built in ND filter. Yes, you can screw a filter on by yourself. Then you suddenly find yourself on a sunny beach and you wish you had your photo bag with you. Not saying global shutter isn't nice feature, but that 250 base ISO can be a bit of a hassle depending on what kind of photography you do just like not everybody is going to benefit from the new shutter.
  - ISL 3y ago
ptsneves 3y ago
Global shutter is essential for serious drone photography or photography from platforms with undamped vibrations like machinery. It means you will have discontinuities in features of the picture. You will need to re-stich the photo or post process it. For video it is just bad. An example of such pixel perfect uses was we were able to know the size of a marking on the ground with centimetre accuracy by counting the pixels. Modern gimbals are amazing and do away with much of the issue but if you are needing pixel accurate features global shutter is the way to go.
- ptsneves 3y ago
  An example of global shutter issues https://youtu.be/qqsDMJ7iyM0?t=86 https://youtu.be/qqsDMJ7iyM0?t=86
  - account42 3y ago
    You mean an example of rolling shutter issues.
    - ptsneves 3y ago
      Yes thanks for the correct. I cannot edit the typo anymore :(
smogcutter 3y ago
> 1/30th of a second is actually a relatively long exposure for a photo. As an aside, in video & motion picture cameras the frame rate isn’t the exposure length. You need to account for the time the shutter is closed. So the real exposure is about 1/60, still slow but much more manageable.
vanderZwan 3y ago
> Some cameras with slower sensors suffer from the rolling shutter effect where fast moving subjects get distorted because the subject or the camera is moving. Think e.g. lampposts looking diagonal when shot from a fast moving car. These days this is the least of your worries with a camera with rolling shutter. I got a Nikon Z-fc, knowing from the reviews that it would have a rolling shutter, because I don't mind these types of distortions. What the reviews didn't mention is that many LED based lights actually alternate red, green and blue LEDs in quick succession. And you see that in photos as horizontal streaks of rapid changes in white balance. This also happens with projectors that are LED based, and CFTs if their drivers aren't fast enough.
- plus 3y ago
  Are you sure that's an artifact of the light source emitting colors sequentially, and not an artifact of the camera sensor detecting colors sequentially?
  - vanderZwan 3y ago
    It only happens with some light sources. If it was the camera it would happen with all of them.
- kruxigt 3y ago
  [dead]

fullspectrumdev 3y ago

Thanks for the explainer - I was wondering what the significance was, and something I do is mess about with cameras for fun.

cubefox 3y ago

The article also mentions the downside of global shutter: lower dynamic range.

codeconscious 3y ago
Thank you, as I might have overlooked this downside had it not been for this comment. The article doesn't make this immediately clear: > It's a 24.6MP camera that Sony says doesn't compromise on ISO performance or dynamic range. Then later: > This might explain the base ISO of 250, which will ultimately limit the camera's maximum dynamic range. Sounds like a compromise to me...

Espressosaurus 3y ago

Not just the global shutter, but 120 FPS with full AF and AE is huge too. The A9III is going to be the best sports camera out there for a few years I think. Of course, you're going to pay through the nose if you want access to that tech. I can't wait for them to gain back the dynamic range and for it to roll down to less expensive cameras in the future.

clan 3y ago

Agreed. Worth mentioning as well: flash sync speed. As you are not dealing with a shutter or progressive capture this will be a thing of the past.

dheera 3y ago

> Cropping the sensor is a common way to counter rolling shutter with current camera Not in my experience. For full-frame 35mm digital cameras, the most common way to counter electronic rolling shutter effects is, ironically, a very fast mechanical shutter. In digital cameras with mechanical shutters, which include all Canon/Nikon/Sony/etc. consumer DSLRs and mirrorless cameras, the electronic shutter programmed to stay open for much longer than the mechanical shutter, which allows there to be a time instant when all pixels are simultaneously electronically open. The mechnical shutter then opens and closes during that time. The rolling shutter on a Sony a7 is about 26ms. Mechanical shutters can beat that easily, and can be as fast as <0.2ms. (Electronic shutters can be faster on a per-line basis. But they will still take 26ms to roll through the image for a rolling shutter sensor. So if your electronic shutter is set to 0.01ms you'll still be seeing 0.01ms exposures at each line but it will take 26ms to roll through the image.)

Espressosaurus 3y ago
Cropping is common in video. For stills, you're correct.
mnw21cam 3y ago
I don't think you're right about mechanical shutters being faster. The type of mechanical shutter on most cameras like this is a focal plane shutter[0]. It has two curtains - an upper one and a lower one. When the shutter is closed, the two overlap. For a long exposure (typically anything longer than 1/100s although some cameras are faster) the lower curtain will fall all the way, then the upper curtain will fall to close it off again. But at faster shutter speeds, the upper curtain will start falling before the lower curtain has reached the bottom, and so you can get exactly the same rolling shutter effect with a mechanical shutter as with an electronic shutter. For very fast shutter speeds, the exposure is a narrow slit between the two curtains that travels down the image at a much slower speed than the exposure time, and this is why most cameras can't synchronise with a flash at speeds faster than 1/100s or so. So therefore the type of mechanical shutter in most DSLRs and mirrorless cameras effectively have a rolling shutter transition time of 4-10ms, which is much more than the 0.2ms you claim. Video-specific cameras are where this might be improved, because you can have a shutter which is a rotating disc, and this can allow faster opening/closing times, because it doesn't need to speed up from a standstill for each frame. There exist central shutters which are mechanical shutters that act as a global shutter, but these are unusual because they need to be built into each lens you attach to the camera. These are typically limited to a maximum speed of 1/500s. [0] https://en.wikipedia.org/wiki/Focal-plane_shutter https://en.wikipedia.org/wiki/Focal-plane_shutter

vouaobrasil 3y ago

Most higher end cameras like the Panasonic G6, Nikon Z8/Z9, etc. hardly have any rolling shutter. You'll certainly NEVER see rolling shutter in any PRACTICAL application for video unless you pan like a true madman, either in photo or in video. (I am a professional photographer and videographer....) In fact for sports and wildlife, you'll NEVER see rolling shutter in pretty much any existing camera, either in photo or video. For photography it's been like this for decades and for videography recently. Where rolling shutter does appear is in the use of the electronic shutter only, but the Nikon Z9 already solved that, same with the Sony a1. The main benefit is flash sync and a very SLIGHT improvement in some types of distortion when shooting at very high shutter speeds. I'd argue that the Nikon Z9 is a much better camera if not wanting flash sync due to its lower base ISO. So to reiterate, the main benefit is not the reduction of rolling shutter, especially since any camera in this price point already has minimal rolling shutter. Global shutters are COOL, and the reduction of rolling shutter is COOL, but not the main point, though of course most future cameras will probably switch to global shutters at some point if the base ISO can be lowered.

andrei_says_ 3y ago
Global shutter allows for much higher flash sync speeds. I shoot dance, often in close proximity, and rolling shutter on canon r6 was a reason enough to upgrade to r6ii.
onetimeuse92304 3y ago
> I'd argue that the Nikon Z9 is a much better camera if not wanting flash sync due to its lower base ISO. Yeah. I think a lot of people focus too much on those "high end" specs and too little about small, practical, quality of life things. I remember how I instantly liked Fuji X100 for its built in ND filter. Yes, you can screw a filter on by yourself. Then you suddenly find yourself on a sunny beach and you wish you had your photo bag with you. Not saying global shutter isn't nice feature, but that 250 base ISO can be a bit of a hassle depending on what kind of photography you do just like not everybody is going to benefit from the new shutter.
- ISL 3y ago

ptsneves 3y ago

Global shutter is essential for serious drone photography or photography from platforms with undamped vibrations like machinery. It means you will have discontinuities in features of the picture. You will need to re-stich the photo or post process it. For video it is just bad. An example of such pixel perfect uses was we were able to know the size of a marking on the ground with centimetre accuracy by counting the pixels. Modern gimbals are amazing and do away with much of the issue but if you are needing pixel accurate features global shutter is the way to go.

ptsneves 3y ago
An example of global shutter issues https://youtu.be/qqsDMJ7iyM0?t=86 https://youtu.be/qqsDMJ7iyM0?t=86
- account42 3y ago
  You mean an example of rolling shutter issues.
  - ptsneves 3y ago
    Yes thanks for the correct. I cannot edit the typo anymore :(

smogcutter 3y ago

> 1/30th of a second is actually a relatively long exposure for a photo. As an aside, in video & motion picture cameras the frame rate isn’t the exposure length. You need to account for the time the shutter is closed. So the real exposure is about 1/60, still slow but much more manageable.

vanderZwan 3y ago

> Some cameras with slower sensors suffer from the rolling shutter effect where fast moving subjects get distorted because the subject or the camera is moving. Think e.g. lampposts looking diagonal when shot from a fast moving car. These days this is the least of your worries with a camera with rolling shutter. I got a Nikon Z-fc, knowing from the reviews that it would have a rolling shutter, because I don't mind these types of distortions. What the reviews didn't mention is that many LED based lights actually alternate red, green and blue LEDs in quick succession. And you see that in photos as horizontal streaks of rapid changes in white balance. This also happens with projectors that are LED based, and CFTs if their drivers aren't fast enough.

plus 3y ago
Are you sure that's an artifact of the light source emitting colors sequentially, and not an artifact of the camera sensor detecting colors sequentially?
- vanderZwan 3y ago
  It only happens with some light sources. If it was the camera it would happen with all of them.
kruxigt 3y ago
[dead]