Some friends of mine said it didn't darken movies and none of us saw one in the theatre yet but i'm allways hearing this on the net, is it true?
How does that happen?
Well there are many reasons, and many more explanations, and unfortunately people who don't know much about cinema projection equipment tend to spend a lot of time putting misinformation on the Internet for others to believe.
Really what you're seeing in a 3D presentation isn't any darker, or at least it shouldn't be if the equipment is set up correctly and playing everything to specification. The problem is there are a number of reasons why people get the impression that 3D is darker.
Here are a few:
1.) They lift the 3-D glasses off and notice a difference in illumination.
2.) They watch a badly presented show and form a generalised opinion based on that.
3.) They read things that misrepresent information, then proceed to believe the misinformation.
As far as #1 goes, these people can be ignored. They're deliberately trying to view a part of the picture that they're not supposed to see and crying over the difference in brightness.
For #2 the technology is still fairly new and those of us in the industry are as frustrated as patrons about the costs and time spent on working the kinks out. There are many obstacles from equipment to training that cause shows to have problems.
For an example of the misinformation problem we need only look as far as Mace Dolex's post above. Fragments of memory have been put together in text format that rework the original piece of journalism (that in itself was dodgy to begin with). The original gripe there was not about 3-D, but how a Sony DLP can be time intensive to convert to a 2-D configuration, causing a contributing problem towards underlit 2-D digital shows. The journalist had written a multi-page rant about Sony's lens changing issues, and yet that technology is but one of several. What about a Christie DLP with a RealD XL unit in front of it? The original article gave Christie and Barco a one-sentence mention if I recall correctly, and yet people will still read it and lump everything into one generalisation.
The old saying goes that "you should not believe everything you hear." Try seeking out the people who know about projectors:
www.film-tech.com