On Mon, 4 Feb 2002 01:02:58 +1100, "Hughy" wrote:

[...]
>Now - I need some more help here. (Please excuse my talking PAL). PAL
>DV is 720 x 576 pixels in a frame. Therefore I presume the maximum
>resolution available is a theoretical 720 vertical lines.

Often stated as 540 TV-lines, or some such...;-)

>Once this
>point is reached, any increase in lens performance (resolution wise) is
>surely wasted?
{...]

No. As with still photography and lens-resolution
vs. film-resolution, TV-resolution and lens-resolution
are better seen together as a resolution system in which
optimizing one side will better approximate the other, but
the best final resolution is always less than the lesser
of the two... Or, if you mate a 300-line lens (yuck! ;-)
with a 540-line medium, the resultant resolution will
be a good bit below 300 lines; if you mate a 1000-line
lens with a 540-line medium, the resulting resolution will
be a good bit below 540 lines, but better than in the first
example; if you could mate a perfect lens with the 540-line
medium, the resultant resolution would closely approach
540 lines... Since 540 lines spread over the width of a
good-sized CCD represents relatively poor resolution in
terms of lens-resolution, a reasonably good lens can bring
the TV-resolution up nearer to 500 lines, and a much better
lens can push it to 530 or so...