This is a complex subject but worth the time to investigate.


"which one is better? 1/2.7" or 1/1.8" ?"

This is the measurement of a digital camera sensor.
1/1.8 is larger.
Typically, if you have more megapixels you want a larger sensor assemby to put the larger quanity of individual sensors onto.

Here is a link that explains sensor size.

http://www.dpreview.com/learn/?/key=Sensor_Sizes

"What is CCD?"
Here is a link that explains the different types of sensors.

http://www.dpreview.com/learn/?/key=sensors

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