To cut to the chase, here's a screenshot with the C500 on the left, and the Pro 9000 on the right. It's a bit overexposed, but smart software will adjust the exposure.
Here's a low-light screenshot with the C500 on the left, and the Pro 9000 on the right.
The Pro 9000 really is better, but it's up to you whether it is worth the extra cost (click to zoom).
To test the cameras I ran luvcview in Linux with out any options, so the cameras are outputting 640x480 without any fancy sharpening or anything.
The first camera I tried was an old Philips SIC4750/27 that I received from a friend. The Philips is a very old web cam (today it's 2009). It has very poor image quality, and poor low light capabilities. Unfortunately, I couldn't get it to work with luvcview, so I don't have a screenshot to show.
The second camera I tried was a Logitech Webcam C500. It has a glass lens and a 1.3MP sensor and according to the box, it can capture video at 1280x1024. I believe it has a fixed focus lens. This camera costs $40-50. The image quality is decent, but the image is on the blurry side. I tested the cameras in a low light environment. It is night time, and there is a single torch lamp in the corner of the room. The image shows a fair amount of noise in this low light environment. I'm used to nice SLR cameras, so I might be more picky than other people.
The third camera I tried was the Logitech Webcam Pro 9000. This has an autofocusing "Zeis" lens, and a 2MP sensor. This camera costs about $80-100. The Pro 9000 is clearly sharper than the C400, and has less noise in the same low light conditions. However, it is not as good as a $100 digital still camera (that can probably take video).
I'm keeping the Pro 9000; it is a bit more expensive than the C500, but the image sharpness and noise level is much better.
