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11-27-2011, 09:00 PM   #1
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K5 weird video strobing/scrolling issue in 1080 mode

I'm getting a glitch that only shows up in the highest quality video mode. If I switch down to 720 it goes away. These scrolling waves of distortion appear on the camera's screen and in recorded video when played back on a computer.

I posted a clip on YouTube that shows what was recorded:

I hope I'm not double-posting this. I tried to post in general troubleshooting but it didn't show up.

11-27-2011, 10:15 PM   #2
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It looks like a video problem, but any chance you were under fluorescent light (which would include the new CFL bulbs) -- specifically a single fluorescent light or bulb? If so, try it again under incandescent or sunlight. Otherwise, don't know what to tell you.

Last edited by vonBaloney; 11-27-2011 at 10:29 PM.
11-27-2011, 10:39 PM   #3
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It might also have something to do with the reduced framerate....

I agree, test it in natural light and see if you can reproduce it.

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11-28-2011, 12:42 AM   #4
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The K-5 can record 1080 video only at 25 fps, but it can do 720 video at 30fps.

If you have certain fluorescent lights that run off of 60 cycle current (like in the U.S.), you may have a frame rate mismatch with the light source at 25 fps. This will sometimes show up as a weird throbbing of the light in the video. (Remember, in a DSLR, the sensor doesn't record the entire image at once, but does it line by line. This is known as a "rolling shutter," and means that parts of the image will be temporally displaced. This will cause some of the image to be exposed when the lighting interval is at its brightest, while other parts of the image will be recorded when the light is at its dimmest.)

As other users have suggested, try shooting in natural light (or a non-cyclic light source, such as tungsten, halogen, or LED) to see if you still have the same problem.


Last edited by jimby; 11-28-2011 at 12:54 AM.
11-28-2011, 08:56 PM   #5
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There were no fluorescent lights in use. I had a tungsten fresnel (ETC Source Four) used for the test I posted and I also tested with a tungsten softlight (ARRI). Under the same lighting conditions, the strobing effect did not occur in 720p mode. Also, the "throbbing" was not limited to surfaces being struck by the light sources, it covers the whole frame. I pointed the camera at a window where daylight was visible and the effect continued. This is something going on inside the camera, not a result of interaction with the environment.

Frame rate is automatic at 1080p, I don't think it can be adjusted, and I made no attempt to do so.

I used to do 24 frame sync on film sets, so I know quite a bit about this specific subject, and it has me quite puzzled.
11-28-2011, 09:23 PM   #6
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The only other time I have seen stuff like this is in the presence of a strong EM field, like near a transformer or other unshielded electrical equipment. Suggest you try it in a different environment before making a final determination that it's the camera.
11-28-2011, 09:25 PM   #7
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QuoteOriginally posted by cb11211 Quote
There were no fluorescent lights in use. I had a tungsten fresnel (ETC Source Four) used for the test I posted and I also tested with a tungsten softlight (ARRI). Under the same lighting conditions, the strobing effect did not occur in 720p mode. Also, the "throbbing" was not limited to surfaces being struck by the light sources, it covers the whole frame. I pointed the camera at a window where daylight was visible and the effect continued. This is something going on inside the camera, not a result of interaction with the environment.

Frame rate is automatic at 1080p, I don't think it can be adjusted, and I made no attempt to do so.

I used to do 24 frame sync on film sets, so I know quite a bit about this specific subject, and it has me quite puzzled.
It did look like a whole frame video problem rather than the lights, but had to rule that out. (I used to shoot film under various lighting conditions too and have seen that effect before.) Let us know if you figure this out or have to get it serviced...

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