Sometimes you can use an unfiltered white light if the hogs haven't been pressured too much, every year our "season" starts right after deer season and we do have hunters take hogs with a unfiltered light. As the season progresses it gets tougher so a red or green light is a must, like I mentioned before I have seen, especially bigger boars, bolt when any light hits them. During orientation I also encourage the hunters to start their lights high and bring it down slowly on the hogs. I have had hunters come in with lights that are too powerful! (about a kajjillion candlepower) If the hogs are close it spooks them every time.