Thread: Pluses of global shutter.

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  1. #1 Pluses of global shutter. 
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    People are touting the GS as a “reason” to buy this camera.

    I have used rolling shutter to advantage when visible on red in the past.


    So, if I am not shooting cars speeding, long lens quick pans, strobes,

    What other advantages does it have? There will no longer be flickering lights and fluctuations in fluorescents?
    Or there will because that’s shutter refresh.

    So for a ‘normal’ shooter, what is the master list of pluses to having GS?
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  2. #2  
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  3. #3  
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    Quote Originally Posted by Dmitry Shijan View Post
    So, like the post says. I have used reds and experienced rolling shutter.

    That said what real world conditions (not helicopters), and not the ones I previously mentions, does GS help in?

    Like, a real world list. If this is such a big deal as some say, to them.
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  4. #4  
    Moderator Phil Holland's Avatar
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    Three words.

    High frequency vibration. Which at the moment will destroy footage from pretty much every camera on the market. Bad enough and it's actually not fixable in post even. If you've ever used an old 5D Mark II, roll on some stuff, and give the camera a good whack. Then try to stabilize and fix the footage. There's things you can do to fix rolling shutter artifacts in post, but the temporal variance combined with that level of vibration produces extraordinarily difficult to fix things.

    Generally high quality digital cinema cameras have a faster sensor readout and this is far less of an issue. Then it gets down to how wheels spin, how geometry distorts when moving the camera through time and space, interacting with strobes, and doing actual handheld work again. Early on we saw some big filmmakers using Komodo in a handheld capacity and I'm betting they are looking at that is "the most fun you can have" with it's strengths.

    Stroboscopic testing has been good so far on Komodo, but I'm curious just how fast I can punch a light and still get a good frame. Normally we used delayed strobes to even get a crisp effect and would slow down the pop to hopefully get a usable image. Now, thus far, it is just a usable image.
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  5. #5  
    Senior Member Aaron Lochert's Avatar
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    Every single aspect of motion will be captured at the same instant. It doesn't matter if something's fast or slow, it's just that all the examples you will see are fast motion examples to better demonstrate.

    Guitar strings:

    https://youtu.be/Dk6o5RAIaj4?t=77

    Helicopter rotors:

    https://www.youtube.com/watch?v=YmEH8z1JWgc

    Fan blades:

    https://www.youtube.com/watch?v=nguv9lOkmXI

    Car wheels:

    https://www.youtube.com/watch?v=alXQWGyX3xk

    Vibrations:

    https://youtu.be/R-h46Zz9YZQ

    As far as flicker goes, you will still have flicker due to the shutter still being a temporal sampling device, but that flicker will no longer have horizontal banding that rolls through the image. It will be a global pulsing effect where one frame will be brighter or darker than the next, but evenly-so. This should be easier for software to fix if it rears its head. Or if you're actually wanting to shoot flickering lights, it won't look strange. Same with the vibration test: software stabilization and motion tracking will have a far easier time tracking the motion when all points in the image were captured at the same instance of time.

    All I can say is that global shutter is a truer, more accurate representation of the scene you're capturing, regardless if things are moving fast or not.


    Edit: Found another really good example of stretching/compression and how the direction that something's moving can dramatically change the nature of the artifact: https://youtu.be/I10PEyfGKNk
    Last edited by Aaron Lochert; 06-15-2020 at 07:01 PM.
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  6. #6  
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    A global shutter produces a coherent image that where every pixel represents exactly the same instant in time within the frame . The difference not only affects what happens when the camera is moving, but when anything is moving within the frame.
    For example think of a bush with hundreds of small leaves blowing in a stiff breeze. Each leaf only occupies a tiny portion of the frame.
    With a global shutter each leaf is completely recorded along with the blur of its motion during every frame interval.
    With a rolling shutter a particular leaf may be scanned in one frame, partially scanned in the next, and missing entirely from the next after that depending on its position when the pixels it covers are scanned.
    To my eye a rolling shutter video clip with small details in rapid motion takes on a more ephemeral less solid appearance. That bush would be a poorly defined blurry mess with a less distinct impression of what it actually is.
    I remember watching an early sample clip from a GH1 that was shooting down into a rocky ravine. A small bird glided through the shot and as it speeded up its wings nearly disappeared as if they had become transparent.
    Then their is geometric distortion, and jello to deal with too. I have a strong preference for the aesthetics of time coherent images.



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  7. #7  
    Photo flash with rolling shutter usually looks like this:
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  8. #8  
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  9. #9  
    Senior Member Brian F Kobylarz's Avatar
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    Instrumentation cinematography.

    In some applications, engineers need to perform complex analysis of individual frames from high speed capture.

    While not a Phantom, the global shutter on the Komodo should make it a valuable tool for slow motion work.
    I still own a 16mm camera that would ramp up to 8000 fps in under a second using a four sided prism as a shutter.
    A marvelous piece of technology for its time.
    I will be very interested in testing the limits of the Komodo in this realm - especially if the system can sync to high speed strobes,
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  10. #10  
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