On Friday, December 21, 2001 at 11:11, Wayne Shumaker
<olympus@xxxxxxxxxxxxxxx>
wrote re "Re: [OM] New Olys" saying:
> As an analog CMOS circuit designer, the only way to get lower noise is
> larger area. A larger sensor with the same number of pixels will have
> bigger pixel cells, allowing each cell to capture more photons and will
> always be lower noise than the equivalent smaller sensor. The only way I can
> see that smaller could be better is that smaller may be faster (lower
> capacitance) and perhaps allow it to multi-sample and integrate out noise,
> or possibly lower power which reduces thermal noise.
Smaller has the major advantage that everything else is smaller (cheaper,
lighter) too. Smaller lenses also mean more depth of field. One digicam
(Sony?) has software that takes a 2nd dark snap after long exposures and
subtracts the noise of the dark snap from the first exposure.
I can just see everyone here arguing about which version of software in the
camera provides the best quality. Maybe a "black" market in smarter
software will develop, much as car aficionados trade illicit ROMS that
maximise power at the cost of pollution.
> Everyone is preoccupied with pixel count these days, but what about the
> z-axis? How many pixels does it take to make an image? Early 35mm
> photographers made great photos with very grainy low res film. My co-worker
> is using a casio digital watch with 120x120 pixels. Not for everyone, sure,
> but it has a whopping 2-4 month battery life! Film is scaleable, need more,
> get a 4x5.
But we're spoiled...
> The limit to using existing SLR lenses has to do with the bucket (pixel
> cell) depth and the angle of incidence at the edges with wider angle lenses.
> (telescopes are generally not wide angle instruments.) I've also noticed
> that the minimum aperture opening is around f11, is this due to the need to
> have a wide enough opening to maintain this near perpendicular angle of
> incidence to the sensor? For example, even a pinhole lens will be blurry
> with an imaging device that has pixel depth. Could someone make an optical
> adapter to parallel up light rays, similar to retro-focus in existing
> lenses? This adapter, if built into the body, could also double as seal for
> the sensor from dust.
Sounds good. That was the import of Oly's presentation discussed here a few
years ago that Digital lenes had to be different from Film lenses.
The parallelising could also be handled by a little lens or sleeve (light
pipe) over each pixel, or by having the sensitive part of the pixel facing
more towards where the light is coming from. Would be nice to have the
angle adjust based on the lens!
> Wayne
>
>
> At 07:52 PM 12/19/2001 -0800, you wrote:
> >...One thing though
> >that kinda worries me is that with a smaller CCD there
> >will be a level where they just can fit any more
> >megapixels onto it right?
> >
> >Mark Lloyd
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