3 or 4 stops? Is that really possible?Had superzooms continued to improve in iso instead of in pixels, then I would have upgraded to a newer superzoom instead of going for GH2 + 100-300. Imagine if the FZ18 had been improved 3-4 stops, staying at 8 mpix? I would have bought one. But I guess the strategy of Pana paid off, I am moving to their more expensive option.
I'm not very familiar with the FZ series (had an FZ30, good controls, not very impressed with IQ). Is the FZ100 the lastest? It has about 50MP/cm2 vs about 30 for the FX18. I suppose that means noise should increase about 70% if they use the same style of sensor? If they've managed to keep it the same, does that mean they could have decreased it by 70% if they'd stayed at 8MP? How many stops is that?
I'm just guessing, I don't know how to compare these things. Even one stop would be very welcome.
Looking at the still life images at ISO 1600 for these two models at http://imaging-resource.com/IMCOMP/COMPS01.HTM, I'd say they didn't manage to keep the noise levels the same.
I've often wondered if it would be practical to simply have a much faster lens on a compact camera, rather than try to allow higher ISO. Those suitable for bird photography are really only about 150mm or less, so f3.5 or even f2.8 would be heavy, but not monsters. But they've never sell enough for them to be practical, especially if they were optimised for best IQ at the long end, so we're stuck with having to use interchangeable lens formats like 4/3 and Micro 4/3, and even bigger lenses to get the speed.