Panasonic Lumix DMC-FZ200 User Manual page 38

There is also a primary color filter above each photosite. These Red,
Green and Blue filters are arranged in a mosaic pattern over the whole
surface of the CMOS sensor.
The most popular arrangement is the "Bayer" system where there are
twice as many Green filters as there are Red and Blue to simulate the
spectral characteristic of our own eyes.
Bonded to the sensor is also an "anti-alias" filter which in effect softens
the image to make it less likely to show "stair stepping" of diagonal lines
in the image.
It is a real compromise between having enough anti-aliasing filter and
effective output resolution.
The more you suppress the stair-stepping the lower the output resolution
and your images look very soft.
Take out the filter altogether and you get problems with "moiré" and
objects like fabrics and brick walls take on a characteristic moiré pattern
– very undesirable in the final image. So what does this mean in the "real
world"?
Well, the size of the actual sensor will directly decide on the optical
characteristics of the lens needed to focus the photons (or light) onto the
sensor.
As you probably know a lens projects a circular image (upside down) to
points of focus (called the focal plane). It is at the focal plane that the
imaging sensor is placed. The image circle must be physically large
enough to cover the diagonals of the imaging sensor.
Imaging circle and
sensor size
produce extremely shallow DOF images.
The imaging circle from the lens covers the
camera sensor. The size of this imaging circle will
define the optics of the lens. The smaller the
imaging circle the smaller the exit diameter of the
rear element of the camera lens. Therefore small
sensors like those in mobile phones have very
small lenses; sensors like those in full frame
cameras need larger lenses to create this image
circle. This leads us nicely into how smaller
sensors have more DOF (depth of field) or
conversely why full frame cameras can
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