Images below are all unmodified 100% crops from the Fuji Finepix F50. ISO was set on the camera but exposure and white-balance was on automatic. The ISO 100 to 1600 are full-resolution 12 megapixels images. For the ISO 3200 shot, the resolution is limited to 6 megapixels by the camera. For the ISO 6400 shot, the resolution is limited to 3 megapixels by the camera.
The crops below show a steady increase in image noise along as the ISO sensitivity is increased. The increase is relatively slow until ISO 800 and then it jumps at ISO 1600. On-screen at 100% there is a slight softness to the images too, but considering these are 12 megapixels images this would not show on most prints or when scaled to fit a standard monitor. It is interesting to see that between ISO 1600 and 6400, the noise pattern is about the same size although the image resolution has decreased.
Overall, the Fuji Finepix F50 is clearly not as noise-free as its predecessors. However, because its resolution is so much higher, most prints from the F50 were comparable to the best lower-resolution cameras, at least until ISO 800, if not until ISO 1600.