Light Value loses ~1 stop per 5 minutes at dusk

Of course, the exact rate varies by latitude and by season.. I measured it in the shade at mid latitudes in July.13:00 8.6616:00 8.6617:00 8.3319:10 820:03 7.6620:18 7.3320:34 720:49 6.3320:57 5.6621:05 521:11 4.3321:18 3.3321:24 1.3321:27 0.6621:32 021:37 -121:40 -221:47 -321:55 -422:00 -5The implication ? Low-light capabilities extend "usable daylight" very little - 5 minutes per stop. I suspect people knew this intuitively, but now there is a number. via /r/photography http://ift.tt/2tpJtYV