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Trouble with Capturing from the Pan AG-DVX1000A


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#1 EddieLooper

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Posted 28 June 2005 - 01:06 PM

Hello all,

Ok, this may be a long thread, but please read because we could use the help.

The company I work for recently performed a green screen shoot for use in a few projects. Our photography looks great, but our problem is with the cinematography. We have a Panasonic AG-DVX100A, which I hear is a "top-of-the-line" camera (I don't know much about all of this, thats just what I heard, I am somewhat new to this whole field). The problem is that our video just does not seem as exceptional as it should be with this camera. It's also not just the green screen, we have used it before and it does not really look all that impressive, but good enough. Now we actually need it to look awesome so we can do some keying. We are capturing it through Adobe Premiere Pro 1.5 using a fire-wire straight form the camera into the computer. We tried both 24p and 30p, and captured at 30 fps. With all this our video still just does not look as it should. If anyone out there knows the best way to capture or knows what we are doing wrong, please let me know, it will be much appreciated. Have a great day and God Bless.

Eddie Looper
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#2 David Cox

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Posted 28 June 2005 - 01:28 PM

Hello,

The first thing for me to check is the subjectiveness of your thought that your video "does not seem as exceptional as it should be with this camera". Of course if your pictures are covered in lines, zits etc etc, then there is a fault or some workflow problem.

But assuming the images are technically "fine" but not to your liking, or at least not up to the standard you were expecting, then we need to think about what you can expect from this camera.

It depends on what your expectation is and what you are comparing it to. For example, you mentioned you thought it was a top of the range camera. To put that in perspective, this camera costs under $4000 including the lens. A "top of the range" digital cinema camera costs over $120,000 excluding the lens. 35mm Film cameras also cost a lot more and of course the cost of usage (film stock and telecine) is a lot higher so needless to say, both of these examples should give better images than a $4k camera.

So its important to "compare apples with apples". The DVX 100A is a highly regarded camera in the mini DV world. But mini DV is a semi-pro format at best, and there are plenty of people on this forum that beleive mini DV should be reserved for wedding videos and baby footage :D

You mentioned green screens. This is a particularly weak point for miniDV. Without getting too technical, the miniDV format is highly compressed and one of the things it does to compress the image data is to effectively record a much lower resolution colour image, which is "superimposed" on a black and white one. The human eye is less sensitive to this colour image and so doesn't really notice to many oddities, and this form of compression (although to a lesser degree) has been used for broadcast television since the beginning of colour transmission. However, if you use miniDV for green screen work, you are effectively using a quarter-resolution image for your keying - because thats all you are getting for your green screen. Therefore, you will almost certainly see artefacts due to this resolution such as increased aliasing around the edges and loss of fine edge detail.

So to summarise, the DVX100A is a well thought of camera that should stand well against any other MiniDV camera. If you feel you have seen better miniDV footage, then maybe you should have the camera checked out. But mini DV is a semi-pro format and it (and the lens on that camera) is no match for a more expensive solution such as digi beta, true HD or film. For green screen work, MiniDV is not recomended.

David Cox
Baraka Post Production
www.baraka.co.uk
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#3 J. Lamar King

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Posted 28 June 2005 - 11:52 PM

Just a note to add to what David said, which is certainly all true. When you capture 24p or 24pa footage in Premiere Pro 1.5 make sure that you capture into that same kind of timeline. i.e. 24p footage capture to 24p timeline, 24pa footage capture to 24pa timeline etc. That program doesn't work very good with mixed footage types and shows up as extreme juddering and ghosting.
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#4 EddieLooper

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Posted 29 June 2005 - 08:05 AM

Thank you both for your help. That clears up quite a bit. Also, I did just notice that "Panasonic 24p" settting in Premiere the other day and believe I will be trying that out here pretty soon. Once again, thank you for your help and have a great day, God Bless.

Eddie
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#5 Alvin Pingol

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Posted 30 June 2005 - 12:02 AM

However, if you use miniDV for green screen work, you are effectively using a quarter-resolution image for your keying - because thats all you are getting for your green screen.

<{POST_SNAPBACK}>


If I'm not mistaken, the green channel is not subsampled in YUV colorspace (MiniDV colorspace). Yet still, the green channel may be sharp, but with red and blue at very low resolutions pulling a clean matte will be difficult.

You should be utilizing more than a quarter of the resolution if you key with green.
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