I totally accept the quality of HS10 from ISO100-1600. If the scene is sufficiently lit, ISO3200 could even be used for large prints.
The only problem is that usually when the camera is zoomed to 720mm, the ISO would be automatically increased (if you are using Program mode) in order to get a clear picture to prevent handshake. In this way, the sharpness, colour and contrast would decrease with increased noise in high ISO setting, expecially when the ISO is increased to 1600 or above, resulting in a seemingly digital zoom image. In bright sunlight, there is no such problem if you can keep the ISO at 100.
