Dim movies? Blame 3D lenses used with 2D movies

It's mainly been seen in AMC, National Amusements, and Regal chains that use Sony digital projectors. Apparently Sony rushed their 3D projector to market and got lockins with theaters that they get the projector for free in exchange for Sony commercials being shown before every movie. The problem is that changing the lens from a 3D to a 2D movie is complex, so most theaters don't do it. As a result, the polarizer required for 3D is left in place for 2D movies, resulting in a huge light loss.

I knew there was a lot of light loss with 3D, but I didn't fully appreciate it until I saw Thor in 2D last week, then my wife and I saw it again in 3D over the weekend and I was amazed at how dim it was.

http://www.boston.com/ae/movies/articles/2011/05/22/misuse_of_3_d_digital_lens_leaves_2_d_movies_in_the_dark/?page=full