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Shutter Speed Question for 4k Filming

Discussion in 'Inspire 1 Help' started by A Story in the Sky, Mar 3, 2015.

  1. A Story in the Sky

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    For those of you who've filmed in 4k I have a question about your settings. The industry adage is to have you shutter speed set to a function of your frame rate, so 24 FPS should be about a shutter speed of 50. Auto setting always seem to have a strange shutter speed, and leave me with rolling shutter artifacts and footage that is less than smooth. Also, the advance settings menu on the app takes up a large amount of the screen, and when I close it, it defaults to basic setting. Anyone have experience and suggestions?
     
    #1 A Story in the Sky, Mar 3, 2015
    Last edited: Mar 3, 2015
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  2. Kilrah

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    Getting the shutter speed there needs stronger ND filters we're all waiting for.

    Don't close the advanced settings tray with the button, swipe it away towards the edge or open/close a menu to hide it (little icon on the side can then bring it back).
     
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  3. PetePerrim

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    Also, I think you'll find that any setting changes actually only stay 'set' if you make them while the tablet is connected to the controller which is also connected to the bird. If you try and tweak settings on the app without the controller and bird switched on it all just defaults back to the previous settings remembered by the Inspire from your previous session. Hope that helps.
     
  4. johnmont250

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    just cut some wratan nd gels to slip in behind the dji filter. simple. why wait?
     
  5. InterMurph

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    When choosing a frame rate in video, you want to balance two extremes:
    1. Shutter is open too long, resulting in blurred motion
    2. Shutter is open too short, resulting in choppy motion
    In cinematography, the right balance is generally 1 / (frame rate x 2), rounded to the nearest speed supported by your camera. So for 24 FPS, it would be 1/50th of a second; for 30 FPS it would be 1/60th of a second, and for 60 FPS it would be 1/125th of a second.

    If that results in video that is too dark, you can definitely keep your shutter open longer, but you are limited to the frame rate (24 FPS = 1/25th, 30 FPS = 1/30th, and 60 FPS = 1/60th). As stated in 1) above, this will result in more motion blur.

    If the ideal setting results in video that is too bright, then you can definitely keep your shutter open for shorter intervals. For example, in 24 FPS video, switching from 1/50th of a second to 1/100th of a second is generally OK, but switching to 1/200th could be trouble, particularly if there is a lot of motion. This is because your shutter is open for a much shorter time, and will miss most of the motion. This results in jumpy video.

    Think of it this way: a car is moving 24 feet per second. At a shutter speed of 1/25th of a second, each frame covers 1 foot of motion. At a shutter speed of 1/50th of a second, each frame covers 6 inches of motion, and the next 6 inches are missed. At a shutter speed of 1/200th of a second, each frame covers 1.5 inches of motion, and the remaining 10.5 inches are missed. As you increase the shutter speed, you miss more of the motion, and the video gets jumpier.

    There are three ways to deal with the problem of an excessive high shutter speed. When you move the shutter speed back towards the ideal, the exposure must be balanced:
    1. By increasing the aperture (f-stop). Since the Inspire camera has a fix f/2.8 aperture, this isn't an option.
    2. By decreasing the ISO setting. The Inspire camera will do this automatically. But this strategy only works until the lowest ISO setting is reached, which is quite easily hit on a bright day.
    3. By adding a neutral density (ND) filter to block the light. The Inspire camera comes with an ND filter; I recommend using it on any moderately bright day. But this is not an extremely strong filter, and as Kilrah mentions above, we could use some stronger options.
    That said, the "jumpy video" problem is not the only one you mentioned. You also mentioned "rolling shutter", which is another beast altogether. If it is rolling shutter you suffer from, the only cure is to eliminate motion from your video.

    Can you post an example of the problems you are having?

    Thanks.
     
  6. Kuba

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    Great article, thanks.
     
  7. Glen

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    Thank you for taking the time to write this InterMurph - really helpful post
     
  8. Scotflieger

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    Excellent explanation thank you. As a stills photographer, it has answered my question on the need for ND filters when videoing.
     
  9. Snowbird

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    Great information, thank you.