I noticed something rather peculiar … I was seeing very high apertures in the middle of the zoom range and a fairly low aperture – f/5.3 – at the end of the zoom range. In fact, the F70 and F80 are both at f/5.6 at 10x, which for them is 270mm equivalent. The F300, on the other hand, is at f/6.2 at 10x, 1/3 stops slower, and then falls to f/5.3 at 15x … 1/6 stop faster than the F70 and F80 at 10x.
It’s all very peculiar … watch the video here to see this in action.
The strange audio whistle you hear is not in the file I uploaded … that was added courtesy YouTube compression :-(
Edit: The next morning, the audio whistle is gone. So YouTube was still processing it in the background while I was watching it. Cool :-)