Digital Home Thoughts: More Megapixels is a Waste

"Remember, this is all at the lens’s widest aperture (i.e., the one giving the poorest lens performance). As you stop down from there, the diffraction just gets worse. Yet today’s models continue their mad race to ever-higher megapixel counts. Ten, twelve—now even 14 Mp are being sold. This is where I start using the word “fraud.” Customers are being sold on these higher numbers with the implication it will make their photos better. This is simply a lie. All the higher megapixels deliver is needlessly bloated file sizes."

The article lays out the physics pretty nicely. The Cliff's Notes version is that as megapixels have climbed, the pixel size on sensor has dropped. At these tiny sizes, light behaves a bit differently than we perceive it. As a result, after about 9 megapixels anything else isn't going to matter other than to make the file size larger.