Re: CCD scanning/exposure (was Re: Canopus ADVC300 ... )

On Sat, 06 May 2006 16:09:31 GMT, in 'rec.video.desktop',
in article <Re: CCD scanning/exposure (was Re: Canopus ADVC300 ... )>,
"David McCall" <david.mccall@xxxxxxxxxxx> wrote:


"dhs" <dhs@xxxxxxxxxxxxx> wrote in message
news:e3ihbj$c3a$1@xxxxxxxxxxxxxxxxxxxx
In article <ntv4521tepm2360m5f0e9lo909ao42cnaf@xxxxxxx>,
Martin Heffels <mot@xxxxxxxxx> wrote:
On Fri, 28 Apr 2006 20:25:38 GMT, "David McCall"
<david.mccall@xxxxxxxxxxx>
wrote:

You got me on that one. That is fascinating.
What video camera has a rotating shutter?
I assume you are talking a mechanical motorized shutter?

Yes, a mechanical shutter. They use it to prevent smear during the
read-out
fase. But this is only for certain types of sensors. Camera's like the
high-end Dalsa Origin and Arri D-20 and the more humble Thomson/Philips
have these. In the Dalsa and Arri the shutter also functions to work as
mirror, because these camera's have an optical viewfinder, because they
are
better to work with than an electronic one (better "resolution ;-) ).

I read the DALSA paper that you referenced in an earlier post.
From that and the posts here, it seems as though modern video
cameras have a shutter of some kind, either mechanical or
electronic such that CCD/CMOS image capture occurs simultaneously,
as in a film camera, correct? If that's the case, then the
Sony hi-def consumer camcorder HDR-HC3 isn't really a 1080*i*
device - it only records the frame as two interlaced fields.
The original frame was captured "progressively" (actually
simultaneously) and the original frame can be restored by
simply combining the two fields without the need for any
further processing to eliminate the artifacts of traditional
interlace-captured images. Correct?

I can't say for sure, but I would think it would capture a field
at a time (just as most CCD cameras do), not the full frame.
That would give you far superior temporal resolution. I would
be disappointed if it didn't. I think they are cheating a bit on the
spatial resolution though.

David


David is correct. All of Sony's HDV camcorders, whether they use CCD
sensors or a CMOS sensor, are true interlaced camcorders.

Because the original frame was *not* captured progressively, it is
*not* possible to simply combine the two fields of a given frame and
get an artifact-free frame -- unless no movement took place during the
interfield time period, of course.

If you want progressive HDV, then consider the JVC GY-HD100U, which
does 720p30 using a GOP length of 6, or wait for the GY-HD200U and
GY-HD250U, due in October, both of which will do 720p60 using a GOP
length of 12.

--
Frank, Independent Consultant, New York, NY
[Please remove 'nojunkmail.' from address to reply via e-mail.]
Read Frank's thoughts on HDV at http://www.humanvalues.net/hdv/
.

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