Originally Posted by
pdxer
noise is simply a function of pixel size. higher megapixel counts with the same size sensor and the same sensor technology means smaller pixels and thus more noise. newer sensors are less noisy than older sensors, so direct comparisons can't always be made by pixel count alone. only if one pixel peeps at high iso settings is it possible to tell the difference. shoot both at iso 100, they'll be virtually indistinguishable.
Noise is actually a function of much more than the pixel size. The quality of the electronics, the quality of the sensor, and even temperature (among many other factors) all contribute to noise. It is easier to have a higher signal to noise ratio with larger pixels because you can collect more light but its also very possible to have more pixels and lower noise. Astronomical CCDs routinely perform very long exposures (minutes long) and after fairly routine noise subtraction produce very clean images.
i have read it. david pogue took photos with an unnamed 13 megapixel camera (most likely a canon 5d, but it's strange that he never stated what it was) and then downsampled the images for the lower resolution images.
This is true, but he later published another article where he admits that this is not the best way to do it. In that article, he describes how one of his readers worked with him to perform another test. In that test, they took one camera and shot the same object multiples times such that when cropped around only that object the same picture was presented but with 3 different megapixel counts. Only 3/50 people correctly figured out which picture had which resolution.