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For more detail on the subject of crater timings at a lunar eclipse, you should consult the paper I co-wrote with Dave Herald in the Journal of the British Astronomical Association, vol. 124, issue 5, 2014, pages 247-253.

 

But I need to stress one point:  No one should try to come up with a clever new way to make crater timings, such as analyzing a video, taking a series of timed digital images, or using some kind of photometer.  The response of an electronic device will surely differ from that of the human eye, meaning you can’t compare such results with the gigantic collection of visual timings over the last couple of centuries.  (Have you ever noticed that the umbra’s edge appears much sharper to the human eye than it does on most photographs?)  In effect, adopting some new technique means tossing out all those prior visual observations and starting over.  And who’s to say that some exotic, “even better” timing method won’t come along a decade or two from now?