The highlight section of the image that I used to set the exposure where clipping was removed is the bright white card. I did so by reading the camera histogram, but also by checking the “clipping blink” warning.
This is the whole scene with highlights that stop just short of clipping, down to dark shadows that are well clipped.
I set the aperture at f16 and took a reading of the exposures in the brightest area, and in the darkest and then a few points above darkest. These were 1/8, 1/15, and 1/45 sec. At 100 ISO there was no discernible noise such that I could find an area where the noise was indistinguishable from the darkness as suggested in the course notes. Perhaps I should try this again at 3200 ISO.
I also set the shutter speed at 1/500 sec and checked the aperture values in the darkest areas, which were f1.4, f2.8. and f4.
By matching the measured areas (with spot metering) with the pixel brightness values I was able to calculate that between the darkest and brightest areas there were 8 stops. I might have expected one or two more stops, but the light was changing all the time I was measuring the spot exposures and a spot exposure reading off a camera meter is still not as accurate as a hand held meter, so I would expect an error possibility of one or two stops.
Very interesting that I was able to match the values and assess the camera’s dynamic range in this way.