The photographs of the sun/moon combination during partial eclipse phases were focused at f/4 on the lens (f/8 actually due to the 2x extender) and then stopped down to f/5.6 (f/11 actually) for all the exposures, and the shutter speed was 1/500 second. The photographs of the corona during totality were made without the solar filter and were also focused at f/8 and taken stopped down at f/11, but the shutter speed was ranged from 1/500 second to as much as 2.5 seconds. The purpose of this bracketing was to capture, in a sequence of photographs, as much of the extended corona as possible. The range of shutter speeds is necessary, because the corona 's brightness decreases dramatically with distance from the photosphere.
I note that the world was so dark during totality that I could not be sure of reading the markings on the camera or the figures showing on its LCD. Having neither the time nor the presence of mind in the face of this sudden, unfamiliar situation to look at the illuminated display in the viewfinder, I was reduced to counting the clicks as I dialed multiple times among my intended exposure times.