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Overscan with SDX 900


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#1 EuropeDOP

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Posted 09 May 2005 - 01:27 AM

We used to work with a Panasonic DVX 100A, now we want to do a project with a Panasonic SDX 900.

We noticed that the first and the last line of the image in the SDX 900 are cropped.


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Is this normal behavior? With the DVX100A the first and the last line are not cropped. Is it possible to adjust this on the SDX 900?
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#2 EuropeDOP

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Posted 09 May 2005 - 04:46 AM

Sorry, my question is very easy. :rolleyes:

Could someone look through the viewfinder of a SDX 900 and tell us if the first and the last line of the image does not have the full size and is cropped?
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#3 Phil Connolly

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Posted 09 May 2005 - 07:14 AM

I've not looked for the viewfinder of a SDX-900, but PAL video doesn't have a complete top or botton line and it should look cropped.
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#4 EuropeDOP

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Posted 09 May 2005 - 08:33 AM

Thank's for your answere Phil:

The PAL image of the Panasonic DVX100A shows the image in full size and no lines cropped. This is different to the SDX 900: In Final Cut Pro (16:9) or on a broadcast monitor you still see the (two) cropped lines of the SDX 900 but the DVX 100A shows the full PAL image. Does the SDX 900 have more resolution than the DVX and therefore shows cropped lines at the beginning and the end? :unsure:
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#5 Phil Rhodes

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Posted 09 May 2005 - 09:03 AM

Hi,

Think about it this way.

PAL is 625 lines. There are two fields. Each of which has... 312.5 lines.

Yes, really. The SDX is correct.

Phil
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#6 Scott Rachal

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Posted 09 May 2005 - 09:27 AM

I'm really scraping the bottom of the memory barrel here, but I seem to recall that an official CCIR-601 spec image has 242.5 scan lines per field. (486 lines total, with the last line of field 1 and the first line of field 2 being 1/2 lines)

See the first graph here:
Field Dominance

This explains the partial lines at the top and bottom of your viewfinder (and your captured image if you use a CCIR-601 capture card to capture the images from DVCPRO tape)

The DVX 100a, being a DV camcorder, using the DV spec of 480 lines, (Not 486) has 240 full lines per field.

I remember seeing those partial lines on any broadcast camera I've ever shot with. Its just NTSC, nothing to do with the SDX900 in particular.

I think this all harkens back to the analog broadcast specs (3.58 MhZ bandwidth X 29.97 cycles per second) etcetera.... that's where the 'partial' lines originate.

-Scott
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#7 EuropeDOP

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Posted 09 May 2005 - 09:41 AM

Thank you, Phil. Thank you, Scott.

I got it... :D
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