RE: Future of Photography (was filmscanners: real value?)

[Clark Guy <guy.clark@sbt.siemens.com>]

HI, Bob!

I'm glad you have some of the real numbers there.  The fact that we are
already under an order of magnitude of a wavelength says to me that we can't
get too much smaller.  After all, there's still the support circuitry for
each CCD element that has to be included on the chip.  That multiplexing
circuitry has to go somewhere.  On top of that, it's already getting
noticibly noisier even though it's still ~7X the wavelength of light.  

One other thing that just occurred to me: aren't there three or four pixels
on the CCD for each actual pixel seen in the image?  In a camera, the Red,
Green, and Blue information is gathered by individual CCD elements (and
maybe one for luminance?) Thus the actual pixel size from the user's
standpoint is somewhat larger than the chip geometry suggests.  In a
scanner, as I understand it, the light cycles through the RGB colors a
single CCD element senses each color in turn.

The chip manufacturers really want to make the chips as small as possible
for yield issues.  My own company is looking at custom chips, and die size
is being fought over from a cost vs. functionality standpoint.  I believe
that if the CCD elements could be made smaller and just as good from a
sensitivity and noise standpoint, they would be and we would be looking at
smaller overal CCD array chips than we are now.

VERY LARGE ICs have been made in the past, but they are very expensive to
make because the yields are so poor.  I don't expect the size therefore to
increase much to include the extra pixels.  (Unless there is some kind a
major revolution in chip manufacture, as I stated before)  Marketing has to
come up with a resolution/noise/cost solution that will be successful, so
from that standpoint, it is a marketing desision in the end.

I really think that you are helping me make my point, even if I am being
over pessimistic.

Guy Clark

-----Original Message-----
From: Murphy, Bob H [mailto:bob.h.murphy@lmco.com]
Sent: Wednesday, January 31, 2001 12:26 PM
To: 'filmscanners@halftone.co.uk'
Subject: RE: Future of Photography (was filmscanners: real value?)


That's right. The pixels I'm talking about, the ones currently in use in the
Nikon 990, are about 3.5 microns or about 7 times the wavelength of light.
And even though they are noisier than the ones in the D1 or D30 for
instance, they are quite good, and when printed at 300dpi the noise is
practically invisible. 

Also, The pixels don't need to get any smaller since at 3.5 microns you can
get about 30 million of them in a chip the size of the one currently used in
the D1 or D30.

As far as getting the wires out, that shouldn't be a problem either,
especially if the imaging device was CMOS since the data can be multiplexed
on-chip.

I think it's just marketing, but time will tell.

  --Bob