The misuse of 3D lenses on 2D movies is sucking all the light out of your theatrical experience.
If you've been going to 2D movies at theaters that also show 3D, you may have noticed a trend. 3D movies are the main focus of theater owners at the moment, but paying exclusive attention to that new tech may be working against those who prefer their movies in two dimensions.
The problem stems from projectionists using the same lens for showing 3D movies as they do for 2D movies. By keeping the dual lens and polarizer in the mix, movies become very dark - to the point that the image can be difficult to see.
Part of the reason for the issue, according to one AMC projectionist, is that changing a lens is much more than a simple mechanical operation. Apparently, the change requires security clearances, passwords, and a bit of know-how that most employees don't have.
If you're at a 2D movie that's looking dark to you, turn around and check the projector. If you see two beams of light, you're getting a much darker picture than you should be.