Rolling Shutter Effect

rgbii
rgbii Website User Posts: 965 Just Starting Out
Hello folks, I'm wondering who has figured out the Rolling Shutter Effect and how best to fine tune it?   I'm mostly interested in it's usage with a Canon 7D, but I'd be interested in hearing for other cameras too.
I tried to find specs on the 7D's shutter, but didn't really find anything.
My big problem with test and playing around with the effect is my system isn't fast enough to play it real time, so any adjustment I make is slowed by rendering or using the preview buffer.

Looking forward to hear what others have learned and discussing the best use for various cameras.
Thanks,
Richard.

Comments

  • Toonman
    Toonman Website User Posts: 81
    Rolling shutter is unfortunately, an inherent part of how the sensor in DSLR cameras work (at least those using CMOS sensors... which is lots of them). From what I've seen, the best way to avoid it (or diminish it somewhat) is (in no particular order, nor all are required)...
    1. Avoid shooting moving vertical lines across your frame, especially in the foreground (i.e. lamp posts).
    2. Avoid fast horizontal movement (especially with elements that are vertical to the frame)
    3. If you have vertical elements in the background, try increasing your DOF, so they will get blurred out.
    4. Try to use a stabilizer of some sort when shooting. The jerkier the camera movement is, the more noticeable the problem becomes.
    I guess these are off the top of my head. Hope it helps!
  • AxelWilkinson
    AxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,247 Staff
    Good info, Toonman, but I think rgbii is asking specifically about the Rolling Shutter effect in Hitfilm, which can help to correct for the effects of using rolling shutter.
    I'm still not an expert in the use of the effect, but here's what I would recommend.  Add your footage to a comp, and move the playhead around to find a frame where the vertical lines are clearly being distorted by the rolling shutter.  Now, move the Correction Slider until the verticals are more vertical, and things appear to be more or less the shape they should be.  Shutter sync should generally be left as it is; if you move it in either direction, you will likely see the left or right edges of the frame become mis-aligned.
    As you move the Correction slider, the entire frame shape will be distorted to straighten the vertical lines.  This results in blank areas being created in the corner, which will be filled with data from surrounding frames.  If you look at the corners, you will likely see some vertical lines along these seams, and there are several ways to handle these seams, using the View menu.  The default Blended option tends to leave obvious lines sometimes, which may or not be an issue when you actually watch the footage back in realtime after rendering. To remove the hard lines, you can change the View to Current Frame, which will use a mirrored copy of the image to fill those areas in, and might give a more subtle result.
  • Toonman
    Toonman Website User Posts: 81
    Ah... I stand corrected.  :D
  • rgbii
    rgbii Website User Posts: 965 Just Starting Out
    No problem Toonman, even though I was aware of things to watch for while shooting, others may benefit from the info.
    Axel, thanks for the info. I have played with it with a clip I had that had extreme 'leaning' in the footage. It was a lot easier to see the effect doing it's job than on some footage I'm playing with now that only has minor issues. In fact, I'm starting to wonder if what I'm seeing is even rolling shutter since it seems to be more of a stutter.  Actually suspecting my new monitor may be the cause :(
    Thanks,
    Richard.
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