CCD size

Can anyone explain how ccd's are sized. they are listed in the specs of most cameras but no one seems to explain which is larger smaller or better. What do the measurements mean?

Generally, newer designs and larger sensors (at a given mp resolution) will give better results. In other words, a newer camera is probably better than an older one. More pixels packed on a smaller sensor can lead to an increase in noise. The size of compact camera's sensors isn't a whole lot different but a DSLR's sensor is much larger - here you'll see a big image quality improvement.

Here are some examples: I have a Nikon Coolpix 5000 which is a compact with a small 5mp sensor and was being discontinued when I bought it at the end of '02 (was introduced about a year or so before then). I recently bought the newly released 7mp Olympus 720SW and it's much better even with it's higher resolution on a similarly sized sensor. The Nikon gets noisy above ISO100 and is pretty bad at 400. The Olympus has a little noise at it's lowest setting of ISO64 but it's not bad. There's more as you go up the scale but at 800 it's better than the Coolpix at 400.

Now, my three year old (released 4+ years ago) 6mp Fuji S2 digital SLR's image quality is way above either of these, partly because the sensor is so much larger.

There is a pretty good explanation of sensor sizes here:

http://www.dpreview.com/learn/?/Glos...r_sizes_01.htm

Thank you. Both answers were a big help.