RE: Question of ethics...."First light"
My opinion if it's too dark to distinquish Horns or not..it's too dark.
Last year (04)in Pa rifle season (In a 3 point on a side zone) I had a buck within 15 yards of me in an open field. It was legal shooting hours but the morning was overcast. It was a nice buck judging by the height and width of the rack. I could have assumed and been 95% confident that it was greater than a 6 point. I could have also easilymade the shot safely. In my humble opinion anything less than 100% when shooting (gun or bow) it's not worth it PERIOD.