Camera propped on worktop (makes a great tripod)
White balance set to fluorescent
Camera on aperture priority
Shots taken in RAW
First shot at ISO200, second at ISO400, and the third at ISO800
Shots developed in Camera RAW4.1 in Bridge CS3
Sharpening sliders set at ‘Amount’ 100, ‘Radius’ 1, ‘Detail’ 50, and ‘Masking’ 0.
The details for the three shots, which are all shown at 100%, are:
ISO200, 1/5 second at f6.3
ISO400 1/8 second at f6.3
ISO800 1/15 second f6.3
Judge the sharpness for yourself. Does the noise at the increased ISO degrade the image to the point that it starts to look mushy? Does the camera bring into play some kind of noise reduction that interferes with getting a sharp image? Personally I think the shots at all sensitivities are indistinguishable for all practical purposes.