The sizes of current image sensor vary quite a bit depending on
At the low end there're 2/3" (and smaller) sensors which are used in "high-end"
P&S (e.g. Canon G5) and pseudo-DSLRs (Sony F828, Minolta A2).
"Classic" D-SLRs require rather big sensors in order to be more or
less "compatible" to existing system lenses designed for the 35mm film
format. The size of the
sensor is a major reason for the price differences between D-SLRs and
of the gang. The bigger the sensor the fewer sensor fit on a chip wafer
- e.g. a single
EOS 1Ds sensor requires the same space on a wafer like ~16 (!) 2/3"
sensors used e.g. in an Minolta A200! Even worse the yield
rate decreases because defective regions on the wafer affect a higher
percentage of the sensor production.
The sensor costs were on of the reason why Olympus introduced the
new 4/3 D-SLR format (about 1/4th of the full 35mm format).
Below you can find two different images that illustrate the
difference between the sensors - also related to the classic 35mm film
format. Observe the difference between the 2/3" sensors (up to 12
megapixels by now) and the full format (up to 20 megapixels).
The following illustration shows the "cropping" compared to full
The 2/3" format isn't even the
smallest image sensor around - in fact it's a rare species.
True P&S cameras usually use 1/1.8"
or even 1/2.7" sensors - see below for a comparison.
Now let's do a little thought experiment ... the Fuji F30 features a
1/1.8" sensor with 6 MP. If we translate this to a
theoretical full frame sensor of the same pixel density we would get
something like 135 MP ... 8-)
Beyond that you may imagine how much advanced the lens design needs to
be in order to be able to exploit the potential of such a sensor ...