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#1 Colin Rich

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Posted 23 January 2009 - 10:22 PM

I'm prepping for a short film to be shot with an HVX200a. In the movie there are many important shots that include standard def, 1990's-era televisions.

During a test shoot, I could not get the rolling horizontal bars to disappear from the tv, despite cycling through all the possible shutter speeds using the synchro scan function. I was viewing the image on the camera's fold out LCD screen.

Any advice on how to remove the flickering lines would be greatly appreciated. Thanks.
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#2 David Mullen ASC

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Posted 24 January 2009 - 12:28 AM

It should work -- generally you have to be around 60 Hz or 1/60th of a second on the shutter (59.94 to be precise.) I'm assuming NTSC of course.
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#3 Colin Rich

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Posted 24 January 2009 - 09:46 AM

Yup it was NTSC. Thanks!
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#4 Walter Graff

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Posted 24 January 2009 - 10:49 AM

Yup it was NTSC. Thanks!


Is it multiple monitors playing together? If so, unless you have something that syncs them all up, you can not get rid of all the rolling. If it is a single monitor, you have not done the procedure properly.
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#5 Brian Drysdale

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Posted 24 January 2009 - 11:25 AM

Are you shooting your short at 24p?

On film a 144 degree shutter is used filming NTSC at 24 fps.
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#6 Walter Graff

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Posted 24 January 2009 - 11:35 AM

Are you shooting your short at 24p?

On film a 144 degree shutter is used filming NTSC at 24 fps.


Good point should have asked!
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#7 David Mullen ASC

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Posted 24 January 2009 - 12:00 PM

It doesn't really matter since it's a video camera and doesn't have a mechanical shutter -- the shutter speed selected is the shutter speed regardless of the frame rate, unless you select an "impossible" speed (longer than the frame rate allows.)

It should be around 59.94 Hz or 1/59.94 of a second (which is why it's a 144 degrees at 23.976 fps.)
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#8 Walter Graff

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Posted 24 January 2009 - 12:45 PM

It doesn't really matter since it's a video camera and doesn't have a mechanical shutter -- the shutter speed selected is the shutter speed regardless of the frame rate, unless you select an "impossible" speed (longer than the frame rate allows.)

It should be around 59.94 Hz or 1/59.94 of a second (which is why it's a 144 degrees at 23.976 fps.)


It still has to be synced and is still affected by the electronic shutter when in default 1/48th at 24p
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#9 Brian Drysdale

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Posted 24 January 2009 - 05:31 PM

It should be around 59.94 Hz or 1/59.94 of a second (which is why it's a 144 degrees at 23.976 fps.)


True, just remembering the Samuelson safe shutter angles for HMI chart.

I had a problem with a bar slowly rolling through a TV shot, turned out the B & W VTR wasn't stable enough. Although, I can't see this being an issue with NTSC.

I'd have thought that playing with the camera's clear scan should find a locking point, so at least it doesn't roll.
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#10 Colin Rich

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Posted 25 January 2009 - 12:50 AM

Are you shooting your short at 24p?

On film a 144 degree shutter is used filming NTSC at 24 fps.



Yes it is 24pN. I'll be trying again tomorrow, I'm sure it'll work thanks to everyone's advice.
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