I like yellow covers for low light situations. I never tried red though.
hey welderboy2577 maybe you can help supermagnum in this tread:
http://www.deerdays.com/Topic.aspx?forum=5&Topic_id=83
For anyone who uses a scope on their rifle / shotgun or crossbow, do you use lens covers? like the slip on kind with tinted lens for low light shooting (just like shooting glasses) If you do what colour do you use yellow / red or clear ??