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My camera is showing distortion when object is moving

  1. Nov 27, 2013 #1
    I just recorded a girl giving a monologue and every time she moves her arms or her body, she becomes wavy until she stops moving. This is a Canon Vixia HF100, so it's a decent camera. Maybe the room was too dark? Maybe the background was causing a problem? Anyone know what could be causing this?

    Thanks.
     
  2. jcsd
  3. Nov 28, 2013 #2

    Borek

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    This is a 2008 model, isn't it? I guess what you see are some compression artifacts, they are sometimes present even in new models. I agree it is disappointing, but I don't find it surprising.

    Not seeing the video it is hard to guess what could be the reason, your ideas (too dark, background) can be correct.
     
  4. Nov 29, 2013 #3
    Yes, that's the model. They're compression artifacts? I wish I could show you the video, but I don't want to post a video of this girl on the internet without her permission. I tried filming myself moving, but I don't see that effect. Maybe it was low lighting or something else, but you're right, it is disappointing. This is a relatively expensive camera, so shouldn't it be able to handle a bit of low light without that happening?
    The reason I bought the camera is because I did research and saw videos online that were shot with this camera, and they look really good. For instance:


    Shouldn't my camera be able to shoot videos that look that good? Maybe my settings need to be changed?

    Thanks.
     
    Last edited by a moderator: Sep 25, 2014
  5. Nov 29, 2013 #4

    Borek

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    Have you shot from a tripod? That's how the video you linked is mostly done, and that can be a pretty important thing. I believe I have seen compression artifacts in the YT video in one of those moment when the camera was moving. Perhaps I am wrong.
     
  6. Nov 30, 2013 #5
    Is this only happening on the camera's screen, or does it carry over to after you've downloaded the video to a computer?
     
  7. Dec 2, 2013 #6

    collinsmark

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    It could just be you need more light.

    Similar to a still camera, each frame is captured at a particular exposure setting. For a given light intensity, the exposure settings are determined by the aperture (f-stop) and shutter speed (not to be confused with cine rate), and possibly the sensor's "ISO" setting.

    Most cameras have an automatic exposure setting that allows the camera to automatically select its own aperture, ISO and shutter speed based on the lighting conditions. Your camera has this capability.

    According to the Canon Vixia HF100 User Manual, the automatic exposure is the only choice. It doesn't seem as though it allows you to select any of these exposure settings yourself (you can tweak the overall exposure if you wish, but you cannot select individual aperture, shutter speed or ISO on this particular camera).

    What may be happening is that given the low-light conditions, the aperture that the camera selects is at maximum, the shutter speed is pretty slow too. Just like with a still camera, movement will blur the image when slow shutter speeds are used. If that's what's going on here, the solution is to provide more light. That way the camera will select a faster shutter speed for the same exposure at the sensor.

    Remember a while ago I mentioned that camera and video accessories can get really expensive, really quickly. This is another reason: lighting.

    Typically in the industry, when shooting indoor scenes all the lamps and lights in the house -- ones that make it into the actual scene -- are replaced with rather dim bulbs. The "real" light doesn't come from those household lamps. Instead, the real light comes from very bright lights made especially for cinematography -- these special lighting fixtures don't make it in front of the camera, so the final viewer never sees them. The viewer assumes that the light is coming from the nearby lamp in the scene. But it's really not. Its coming from a really bright light source (or perhaps multiple sources) off to the side and out of view.

    As a matter of fact, even outdoor, night scenes are often actually shot during the daytime, sometimes in full sunlight, and then they are made to look like nighttime scenes in post processing, by applying a blue filter. (And there maybe be other filtering tricks involved besides just the blue one.)

    So in short, you might wish to try more light, one way or another.
     
    Last edited: Dec 3, 2013
  8. Dec 2, 2013 #7

    collinsmark

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    Also, here is a trick if the scene calls for a dark room. (Suppose you actually want to make it look like the scene is in the nighttime darkness.)

    Don't actually make the room dark.

    Give the girl and the room good lighting (just make sure the actual light source is not in view of the camera).

    Using your camera's controls:
    1. If the joystick guide does not appear on screen, press the SET to display it. If [EXP] does not appear on the joystick guide, repeatedly push the joystick <down> toward [NEXT] to display it.
    2. Push the joystick toward [EXP]. The exposure adjustment indicator and the neutral value of "+/-0" appear on the screen.
    3. Adjust the <left and right> to reduce the brightness of the image. Try to make the value more negative. The adjustment range and the length of the exposure adjustment indicator will vary depending on the initial brightness of the picture.
    4. Press SET. The exposure adjustment indicator will change to white and the exposure will be locked. If you operate the zoom during exposure lock, the brightness of the image may change. During exposure lock, press SET and push the joystick <up> toward [EXP] again to return the camcorder to automatic exposure.

    If you can apply a blue filter in post processing [digitally on the computer], that might help too.

    Edit: Alternately, you can also shoot the scene with normal exposure, and then reduce the apparent exposure later, on the computer, in post.

    Another edit: you also might wish to reduce the color saturation a little. You can do this in your camcorder's CUSTOM settings. Change the COL.DEPTH to (-)Shallower colors. That, combined with the lower exposure and blue filter, should make almost any scene look as though it was taken at night.
     
    Last edited: Dec 2, 2013
  9. Dec 2, 2013 #8

    collinsmark

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  10. Dec 3, 2013 #9

    Andy Resnick

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    Based on your description, I suspect the HF100 uses a 'rolling shutter', similar to the iPhone:

    http://www.dpreview.com/news/2011/7/15/iphonerollingshutter
     
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