Basically, with digital images, the size of the sensor is important, and the number of pixels.
Many people think that more pixels = better pictures...this is NOT true!
The pixel density plays an important role here.
Some manufacturers use the same sensors...but one says 10MP and the other 14MP...the difference is just the software.
Comparing images: at ISO 100 there will be no detectable difference, but at ISO 400 the image will be worse with the 14MP camera (remember, this is with the same sensor). The main problem is that the image will have more color noise.
A good example is in the list below: Canon produced the G10 a couple of years ago...and squeezed 14MP out of the sensor. Users complained about the color noise. The next model, the G11, uses the SAME sensor, but now with only 10MP. The result is far cleaner images!
Canon EOS 1D Mark IV. 16.1 million effective pixels. 3.1 MP/cmÂ² pixel density â‚¬5000
Canon EOS 5D Mark II. 21.0 million effective pixels. 2.4 MP/cmÂ² pixel density â‚¬2600
Canon EOS 7D. 18.0 million effective pixels. 5.4 MP/cmÂ² pixel density â‚¬1600
Canon EOS 500D. 15.1 million effective pixels. 4.5 MP/cmÂ² pixel density â‚¬600
Canon PowerShot G11. 10.0 million effective pixels. 23 MP/cmÂ² pixel density â‚¬500
Canon PowerShot G10. 14.7 million effective pixels. 34 MP/cmÂ² pixel density (no longer available new)
What does this mean for the average user? Not a lot, but if you do a lot of low light photography and need to select ISO 400 or higher, then you can expect to see this effect.
If you are looking for good quality images, then look at the size of the chip and the number of pixels. Of the current big three, Canon, Nikon, and Sony, Canon and Nikon are about the same, whereas the Sony is not very good at dealing with color noise. This is a generalization and may change with new models.
A lot depends on how much you want to spend, and what type of camera you prefer. My camera of choice right now is the Canon 5D II, but I have the Canon G11 because I like to have it with me all the time and itÂ´s fast to use and the image quality is very good. A good compromise, looking at the Canon examples above, would be the 500D...as you can see the pixel density is not anywhere near as high as the G11, but it will be a lot cheaper than the 7D or 5D
There are lots of reviews and comparisons on line. This is one of the best places to check them out