>Subject: [OM] OM System digital possibilities
>... IMO, it should be cheaper to produce a CCD
>with a larger surface area while maintaining resolution of a smaller
>CCD. What I mean is that for the same resolution, wouldn't increasing
>the Die Size mean that the cost is lower?
In semiconductor manufacturing, the biggest correlator to price is die
size. High-purity single-crystal silicon wafers are expensive, and random
imperfections and impurities mean not all of a wafer may be usable. For
this reason, as die size goes up, yield goes down, further pressuring
price. I don't see 36mm by 24mm CCD arrays as an economically viable
situation for at least several years.
Not only that, but the way CCDs operate works against larger size. The
cells are tiny capacitors -- if you make the cells larger, they require
MORE electrons to pump between cells, decreasing sensitivity. If you make
more cells, the leakage between them becomes greater, reducing signal to
noise ratio, and the time to clock out an image is longer, reducing the
equivalent "film speed." This is why you don't see big sensors for more
money -- there's a technology wall, and it's moving much slower than
Moore's Law. (Technology doubling every 18 months.)
(It is possible to make huge CCD sensons work if they are cooled, as used
in telescope photography.)
I think the future is in CMOS sensors. They have many of the same
limitations of CCD sensors, save one: image processing circuitry is easily
put on the same chip. CCD sensors require special voltages, and "glue"
chips in order to work with standard digital electronics, but CMOS will not.
If we are to see a 36mm by 24mm array, I predict it will be in CMOS, on a
36mm square die, with the rest of the die taken up with basically a full
microcomputer for image processing, and it will have perhaps 16 million
cells, but this is at least several years away.
What about just mounting a Zuik in front of a "standard" CCD array? Well,
since the Zuikos are optimized for 35mm, they won't perform as well with a
smaller sensor, and they will several times less wide -- an 18mm lens might
be the best chance of getting a lens with "normal" perspective, and less
light is gathered. (It would be the same as cropping the smaller sensor
size out of a 35mm negative.)
Even with those limitations, it might prove interesting to kludge an OM
mount onto a cheapo digital camera. I'm threatening my ViviCam 3100 with
such a death after the warranty runs out if I ever get the free time!
: Jan Steinman <mailto:jans@xxxxxxxxxxx>
: 19280 Rydman Court, West Linn, OR 97068-1331 USA
: +1.503.635.3229
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|