I went out to Roger's Reservoir with a brand new Canon 5D Mk2 where 5 years ago I photographed the stars in the sky with a then new Canon 10D. Using the exact same exposure settings I found the northern sky to be no longer black.

The pink glow is Bradford. Adjusting the black level in PhotoShop restored the black.

And zooming in. The 10D is a 6 megapixel camera while the 5D Mk2 is 21 megapixels.