On Fri, 22 Jun 2001 19:59:24 GMT, "Alexander Ibrahim" wrote:

>Uh...in interlaced video every other scan line is omitted, so you really
>have 240/30. That is interlaced together to create a 480/30 signal. The
>interlace is why you get the jaggies.
>
>So you are really comparing two 240/30i pictures, slightly offset and
>480/30p. (At acquisition)
>
>Now does it make more sense ? Standard interlace video (NTSC) has more
>temporal resolution, progressive has more spatial, but less temporal.

This does not make sense... In 480I, you have two fields,
skipping alternate scan lines, every 1/60th second. Add them
together, and you have a whole frame at 1/30th second, with
equal spacial resolution to 480p, but greater temporal
resolution due to the dual fields spread in time within the
1/30th second/frame interval (when seen on an interlaced
TV). This is simply a technically superior way of making
an image intended for an interlaced display (by
definition...;-).

>Now, if you are going to display this on a TV monitor...well you get an
>interlaced picture in any case. Progressive will be split into fields, just
>like the 30i. So, for video there is no point in using progressive unless
>you have a progressive monitor or are displaying on a computer or projecting
>in progressive. There can be a difference for film applications though.
>
>As to National Geographic...my source is Videography magazine January 2001.
>I didn't believe Videography so I asked National Geo. They said that
>principle photography was always done on 35mm, but they did use video
>cameras for certain shots, where video was easier or more practical.They
>tried to avoid it. They were looking into moving to HD video entirely and
>have produced a couple of shows that way.

I know someone who produces work for NG - he moved from
film to video (BetaSP, and more recently, to Mini-DV)
quite some time ago...