Pengwuino said:
What's the scoops? What's the lowdown PF! TELL MEEEEEEE
I'm late to the party, but since my camera is in the shop I've actually gotten some work done :)
Anyhow, there's some excellent comments already. From my perspective, pixel count is useless at the first or even second approximation. What is *far* more important is the sensor size and pixel size- the first is well defined, the second less so. Because we are considering the sensor characteristics, let's first simplify to 'perfect imaging' and a monochrome sensor.
Keeping the print size constant, increasing the sensor size will provide better quality images. Thus, a poster-size print from a cell phone camera is silly, from a 35mm sensor borderline silly, but looks good from a medium format (2" x 3") and great from a large-format negative. This is because less magnification is needed to get to the final print. There are other benefits to larger image formats: decreased depth of field, for example. In the extreme, large format cameras (technical or view cameras) give you complete freedom to locate and orient the plane of best focus. When reasonably priced medium format digital backs come out, I'm getting one.
Larger pixels are beneficial for low-light imaging, but don't have the best spatial resolution. Thus, camera phones can get away with 1-micron pixels (since there's a ton of light at daytime), while my EMCCD camera has 15 micron sized pixels. Pixel count has been increasing over time because the manufacturers have improved the electronic noise characteristics of the amplifiers, thus allowing the pixel size to decrease while keeping amplifier noise to acceptable levels. Obviously, pixel size and pixel count are related...
The twist is that color sensors are totally different from monochrome sensors due to the Bayer filter- the idea of 'pixel size' is greatly complicated. As others mention, even the notion of pixel count is questionable for sensors with a Bayer filter.
In terms of lens performance, the smaller the sensor size, the smaller and more easily corrected the lens. Discussing 'resolution limits' of a lens is fairly straightforward, but the Bayer filter complicates the reality- as a rule of thumb, the lens is matched to the sensor size, not the pixel size. While the tiny lens on a camera phone works great with the tiny sensor, trying to use that lens with a 35mm format sensor is folly. Likewise, using a Schneider super angulon lens with a 35mm sensor is a waste of good glass. I have seen lots of claims that operating lenses at f-numbers less than 5.6 means the overall image is limited by the pixel size not lens performance, and that may be true- except for depth of field considerations.
In the end, for me, the primary consideration (other than price) is sensor size. Larger sensors give me wider fields of view and more room to crop. As for what is the 'best camera', the best camera for you is the one you use all the time. Saying "you don't need anything more than X pixels" is a lot like saying "you don't need more than 64 kB of RAM"- if you are old enough to remember *that*.