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uri soglowek
canon xh a1 and grenn screen
on Oct 7, 2008 at 7:27:54 pm

Hi guys,
i am new to HDV and advanced editing (so take it easy on me...)

i am shooting with a canon xh a1 and i have a project to do an Green Screen.

my questions are:
1. should i shoot DV or HDV? which is better for that?

2. what would give me the best results - Firewire capture or SDI capture? infact what is the main reason to get SDI cards?

3. on a previous project i did i captured HDV via firewire and got a lot of noise and a video that is hard to key? what is the reason for that?

thanks

Uri


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TL Westgate
Re: canon xh a1 and grenn screen
on Oct 8, 2008 at 1:22:13 pm

Shoot in HD, and if you can, capture with an HD card. Don't tape it or capture through firewire - then it's compressed. Capturing an HD signal would be the cleanest.

-- TL


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uri soglowek
Re: canon xh a1 and grenn screen
on Oct 8, 2008 at 7:52:08 pm

thanks,

so just to see if i get you right -

you say i should shoot in HDV and capture directly to the computer via SDI card?

thanks again.

uri



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TL Westgate
Re: canon xh a1 and grenn screen
on Oct 9, 2008 at 1:02:41 pm

No, don't "shoot" with the camera onto tape. Get an HD capture card and feed that with a signal from the camera. Capture with the computer. This way, the signal isn't being compressed with an HDV codec. It's a real HD signal.

-- TL


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ed molina
Re: canon xh a1 and grenn screen
on Oct 9, 2008 at 2:49:18 pm

That would be great, except there is no hd sdi out on this camera. Only composite and firewire.



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ed molina
Re: canon xh a1 and grenn screen
on Oct 9, 2008 at 2:54:59 pm

You could however, use a compositing program and try to seperate the 3 channels (RGB) and provide
a blur on the green channel and recombine them. This should eleviate most of the noise that you get with compression. Thats if you intend to shoot HDV. Cheers!



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uri soglowek
Re: canon xh a1 and grenn screen
on Oct 10, 2008 at 3:39:35 pm

OK got it.

how do i split the 2 channels and then recombin them. i am using After effects for compositing but any instructions on any other program would help too.

another thing-

would i be better off shooting the whole thing SD? (the clients wants it posted on the Net at the end)

thanks again!!

Uri



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TL Westgate
Re: canon xh a1 and grenn screen
on Oct 13, 2008 at 12:36:05 pm

[ed molina] "Only composite and firewire."

Right, use the composite HD outs. It's uncompressed HD compared to compressed HDV.

-- TL


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Sean Webb
Re: canon xh a1 and grenn screen
on Oct 10, 2008 at 2:13:30 am

I shoot two greenscreen shows with multiple Canon XH-A1s (posted at shakeitup.tv) and lighting of the greenscreeen is the biggest factor in getting a good greenscreen shoot.

Lighting may also be your issue with artifacts coming from the camera. Low light will add artifacts 9 out of 10 times. If you want to have a dark/normal picture, it's always best to overlight your scene (without over-driving the CCDs), then increase black and dim the highs in post later. If your artifacts are showing up on the green screen, you need better/more even lighting on the green.

Look at the first few seconds of the G-Lab Episode 7 (that will be posted in a few hours, but is up right now in iTunes), and you will see the green backdrop I assembled with painted drywall and painted floor (flat paint). Notice the differences from some shadows vs the well lit areas. The entire screen is well lit (four soft lights for JUST the green backdrop), but there is still variance that requires me to adjust tolerances to get all the green out in post.

I use the chroma-keyer option in FCP, as that it works better and is sharper that the green screen filters.

Hope this helps.
Sean@ShakeItUp.TV



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