DIY free gopro polarizer/neutral density filter
So a couple years ago I had a gopro, and it took great footage. Unless it was sunny, then all the sudden my on-snow videos looked like crap. So I decided to improvise a polarizing filter to cut glare off the snow.
I had a lightbulb moment and went to the movie theater, and asked for a couple pairs of 3D glasses (NOT the red/blue ones...). They gave me three pairs without question.
New 3D movies use circular polarization to project two separate images. Each lens cuts out one of the images, cuz one is clockwise polarized, and the other is counter clockwise.
But... when you flip the glasses around, they become a linear polarizer, and the "quarter retarder layer" becomes a neutral density filter....
So you cut two circles out of the lenses, and keep trimming them down till they fit into the lens pocket inside the go-pro case. Before you insert the filter, you have to make sure it is aligned properly. Look at an LCD monitor through the filter, and rotate it till it cuts out the screens light. It will do so at a 45 degree angle, cuz that is how LCDs do. So turn the gopro case to a 45, and then carefully put the filter in there so it cuts like out along the horizontal when in the case.
Voila! enjoy your free gopro mega-upgrade. The footage difference is incredible in the sun.
As a side/technical benefit, the filter works to lower the stops, smoothing out the footage.
