[opendtv] Re: MPs back Ofcom stance on spectrum sale
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 28 May 2007 19:37:18 -0400
Craig Birkmaier wrote:
>> I think Mark Schubin indicated that new cameras are
>> available now with sensors the size of 35mm movie film
>> frames (18mm X 24mm). That should take a lot of cost
>> out of the lens, and should make those cameras good
>> candidates for 1080p acquisition.
>
> No, it increases the cost of the lens.
Wrong, Craig. You can find any number of consumer-grade 35mm lenses good
for as much as 100 lines/mm at the image center, and maybe half that
much at the edges. The ones I'm referring to are for 35mm still cameras,
so they are for 24mm X 36mm film frames. They would provide very good
performance in the smaller movie frame. I assume 35mm movie cameras can
benefit from the same lens technology. (Nikon, Carl Zeiss, Schneider are
some good brand names.)
Do the math, and you'll see that a lens capable of 70 lines/mm or so,
making that an average figure across the frame, is capable of about 16
Mpels of image resolution. Plenty adequate for 1080p, and at a cost
(street value) of only a few hundred $.
And the large image area promotes good MTF, because it allows wide
spacing between pixels in the sensor.
> You keep saying this, but we are still a LONG LONG way
> from having compression efficiency that can DELIVER the
> extra detail in 1080@60P with enough headroom for the
> peak bit rates needed.
As I said, 2.25X better than what we do now with H.262. If you think we
are a long way from that, you must not have a lot of faith in H.264 and
its upcoming tweaks. Either that, or you have computed some other factor
and not divulged the information or how you arrived at the figure.
Bert
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