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Old April 24th, 2004, 01:19 PM   #1
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Join Date: Apr 2004
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questions on my mind!?

i have a few questions on my mind...need lite bulbs:)

1) can we capture the high defination image (with the high resolution)from the hd camera through a firewire?

2) my sony trv has a setting as 6db and 18 db.these are the gain values.what are they? on a broadcast camera you have an aparture width and if u want more light but cant make the aparture wider you add gain.right!..but the trv models have electronic apartures.no moving parts. so what is the gain for?
and does grains add everytime i add gain?

3)does neutral density filters work with these electronic apartured cameras?how?

4)is there a way i can capture dv without making it be codeced through the dv-codec?raw avi through firewire?would it be better when shooting in front of bluescreen directly capturing to harddisk?

5)am i asking too much?:)

thanx
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Old April 24th, 2004, 04:26 PM   #2
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Hi Dogus...

1) can we capture the high defination image (with the high resolution)from the hd camera through a firewire?

-- Apple last weekend demonstrated a Panasonic HD deck that did exactly that. The deck, however, is listed at $25,000. It's a deal for an HD deck, but somewhat stratospheric compared to the price of DV equipment. Image quality was stunning.

2) my sony trv has a setting as 6db and 18 db.these are the gain values.what are they? on a broadcast camera you have an aparture width and if u want more light but cant make the aparture wider you add gain.right!..but the trv models have electronic apartures.no moving parts. so what is the gain for?
and does grains add everytime i add gain?

-- Gain is simply a boost of the image signal. Broadcast cameras also have gain settings, some as high as 36 dB. Yes, you can't help get added grain along the way as the noise is amplified along with the desired parts of the signal. Still, with some cameras it's not as bad as others.

3)does neutral density filters work with these electronic apartured cameras?how?

-- Yes they do. They work the same way as sunglasses do to your eyes by reducing the amount passing through them.

4)is there a way i can capture dv without making it be codeced through the dv-codec?raw avi through firewire?would it be better when shooting in front of bluescreen directly capturing to harddisk?

-- The best way is to capture DV in its native codec via Firewire. That way the digital data stored on the tape is passed through into the editing system without any conversions.

-- As for bluescreen, there can be some problems when trying to do this with the DV codec. The color information (resolution) is reduced in order to keep the total amount of data below a certain limit. As a result, the image itself looks sharp (the luminance signal carries all of the detail) while the color is not nearly as crisp (the chroma part of the signal is the equivalent of coloring over a line drawing with watercolor). When you look at the color channels individually, you'll notice that they will look rather rough. And it's this problem that makes chromakeying difficult with a DV signal, whether it's on tape or directly off the camera via Firewire.

There are ways around this. One is to use green instead of blue. DV's green channel has more information than the blue or red channels and therefore appears cleaner. You can also soften the channel that will be keyed (green or blue) to reduce the aliasing (stair-stepping) in a typical matte that gets extracted from the signal.

Video formats with higher amounts of color information will provide much more detail and it's possible to extract a much more accurate matte. That's why some of Panasonic's DVCPro formats are preferred for these types of jobs.

5)am i asking too much?:)

-- Nah! :-)

Dean Sensui
Base Two Productions
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