Originally Posted by
Namida12
...If I understand correctly mounting a light upside down the lens needs to be rotated 180 degrees because a lot of headlight beams that have lens designed with a sharp cutoff, similar to modern automotive headlights...
Very few lights have sharp cutoffs, except in Germany (and maybe other EU countries) where lights are required to have sharp cutoffs. The large majority of lights available in the US have circular or elliptical beams so can be mounted upside down without affecting the beam.