Polarized Beetle 1
Polarized Beetle 2
The beetle reflects circularly polarized light. A filter in front of the camera lens blocks that polarization, but the light reflecting from the mirror flips polarization and passes through the filter.
swans on tea
Just another SFN Blogs site
Borrow a pair of 3-D movie eyeglasses, look in a mirror, close one eye. Though which eye are you looking at the image?