[kmeisthax]

3D requires inserting an extra device into the image path to split the projector light into polarized halves, otherwise the 3D glasses don't work. Because of how light works, half the light is thrown away. So you either have a darker picture or you jack up the light (which, according to theater owners, means more wear on the projector's light source).

Now, in an ordinary scenario, you'd just have the projectionist remove the extra polarizing step from the image path for 2D showings. Except, remember, all of these projectors have DRM specifically to control who is allowed to put things in the image path of the projector. So now management has to be called in every time a theater needs to change over from a 2D or a 3D film.

Or you follow the path of least resistance and just leave all the 3D crap on the projectors all the time, keeping it at the same brightness for 2D (to save money on maintenance), which results in everything being darker.

[Thlom]

It's been a few years since I was in the industry, but I don't think this is entirely correct. As far as I remember the polarizer (or for Dolby 3D, the color wheel) was placed on a rail system to be slid in and out of the light path when required (It's possible that cheaper/older versions can't be automated). The polarizer is placed outside of the projector in front of the lens so no password is required to remove it. There is a security step between the projector and the playback server, but that sits on the first PCB the data signal from server hits on the projector (If I remember correctly).

With regards to the projectors light source you are correct, higher illumination means more wear on the XENON lamp in older projectors. If you have the polarizer in front of the lens at all times that would be a problem. With newer laser projectors I don't think higher illumination is a big problem for the longevity of the laser.

In any case, projectionists barley exists anymore and cinema managers knows next to nothing about the technical aspect of the business. Basically everything is automated to such a degree that all the cinema chain management needs to do is to populate the ticketing system, then films, advertisements, trailers and announcements are automatically downloaded, playlists created, distributed to screens and scheduled. Lights, projectors, doors, curtains and so in is also automated.