There are two fundamentally different types of sensor. "Full-frame" and
"interline". "Full-frame" in this context has nothing to do with the
size of the sensor but rather its method of operation.
A full-frame sensor must be protected from light before and immediately
after exposure as it empties the charges from the entire sensor's pixels
into storage. Because of this it requires an external shutter just like
film. And, since you can't see through it or the shutter, if it's in a
DSLR you need a reflex mirror to be able to see around it and through
the lens.
An interline sensor shifts the pixel data out a line at a time and is
able to start building the next image while the first one is going out.
Using this type of sensor allows use of an electronic shutter and also
allows feeding a real-time image to a viewing screen. This is the type
of sensor that's in point and shoots and your A200 (which has both a
mechanical and electronic shutter). The reason this type of sensor is
not used in DSLR's (as I understand it) is that the per-pixel
electronics are on the surface of the chip next to the photo-diode. The
photo-diode area is thus not maximized as it is in the full-frame design.
Come to think of it this probably has some implications for the recent
discussion of the Fuji F10's low noise. The F10 is achieving relatively
low noise and is doing so using an interline sensor with less than
optimally sized photo-diodes. Does this mean even better performance is
available applying similar technology to a full-frame design? Or maybe
similar technology can't be applied to a full-frame design.
Chuck Norcutt
Willie Wonka wrote:
> I am not sure if I understand, Winsor. Isn't the mirror down during
> focusing? And here is an even dumber question: Can't you use the LCD
> on a DSLR to focus, before taking the picture? And if you can, I
> don't see any problem implementing the feature I have on mine. Be
> patient, you are explaining this to someone who takes pictures of
> static subjects only, I see now how this method of focusing could be
> a little problematic with stuff that moves. Thanks Boris
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|