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Poor Picture At Your Local Cinema?
The Hub writes "Have you ever noticed that the picture in your local movie theater is too dark or grainy? The Boston Globe does some good ol' fashioned investigative reporting to find the culprit. Apparently, the cause is linked to some 3D digital projectors requiring a technically challenging lens switch for 2D movies that sometimes doesn't happen."
This is actually due to the fact that Sony digital projectors are so locked down with DRM that even changing the lens requires all kinds of password checks (which can potentially lock the camera down if not done correctly).
Sadly, this is one of the problems that digital projectors were *supposed* to fix. For years, it was a infamous practice for theater managers to extend projector bulb life by reducing the power of the lamp. Since most people don't notice (having no idea how the movie is *supposed* to look), they could get away with it. Roger Ebert in particular complained about this practice for decades (even organizing protests at certain theaters engaging in the practice). When digital projection came along, one of the selling points was that it produced a much more consistent image (and managers couldn't futz with it--reducing bulb strength, etc.).
Now, thanks to our good friends at Sony, it would seem like we're right back where we started from (maybe even worse, since this produces an even darker image than one of the celluloid projectors at half power).
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But then, I might not be going blind from a lack of a girlfriend. jk
Having to work for a living is the root of all evil.
trying to get modded up for pointing out that people hate 3d?
To save costs, most theaters do not have a projector operator on staff anymore. So little or no corrections are made for different films.
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
I read that story earlier. It doesn't sound so much like investigative journalism as it does like local projectionists raised a shitty on a reporter's answering machine and the reporter recast the rant in story form, plus a couple of phone calls.
Investigative journalism would have got more out of Sony and the theater owners before going to press.
And yes, Sony has been screwing the pooch on all fronts (audio gear, online security, production, projection) for the past several years. Their corporate culture has become one of doing things cheap. They may no longer have any idea what "quality" means beyond the narrow ISO 9000 version of "every unit matches the spec".
Digital cameras are criticized for low dynamic range, especially in dark light scenes,
lower spatial resolution, like smke or sharp edges,
lower temporal resolution, like splashing water scenes, etc.
A good camera man or director can work around these flaws.
And it's not just picture issues, but as TFA mentioned there are sometimes sound problems that go uncorrected for long periods. I drastically reduced my movie-going years ago when I realized I could invest a few grand at home, and come pretty darn close to the theater experience, in some cases surpass it. If I'm paying $10-$15 for a movie ticket, I expect a properly calibrated projector and sound system. Oh and let's all be surprised at once that Sony locks down their pro equipment even tighter than the consumer shit.
This is actually due to the fact that Sony digital projectors are so locked down with DRM that even changing the lens requires all kinds of password checks (which can potentially lock the camera down if not done correctly).
1) Camera?! er, not quite...that would be projector. 2) Why is this a DRM issue? It sounds like a (really bad) implementation issue. All the other projector models still have to deal with the same DRM (Hollywood is notoriously twitchy about this and there is no additional DRM on the Sony projectors that I've heard about...), but they don't have this issue when switching between 2D/3D films. The Sony 4K with Real D setup just isn't designed well from a usability point of view, and many modern multiplexes have shown they can screw up even the most basic of things. Also, it doesn't help that Real D needs a silver screen; that's a whole new source of image degradation that would be nice to do without (that's not unique to Sony).
Twoply.
Why else would they be crippling themselves by making going to the movies even worse than it was before? It certainly can't be because they're making tons of money by showing the films to begin with. And it certainly isn't because of skyrocketing ticket and concession stand prices. Or that they're fighting to keep calorie counts off the menus.
They'd have a good reason for making people not want to go, right? Right?
Profits.
Introducing DRM into component swapping is intended to eliminate third-party replacement parts, thus allowing the manufacturer to completely control the product cycle, and allowing them to charge any price for replacement parts.
Really though you pay out the nose for this experience and projection just is not up to par, especially now days where you might sit 2 foot away from a HD screen all day then walk into a movie theatre.
2) Why is this a DRM issue? It sounds like a (really bad) implementation issue. All the other projector models still have to deal with the same DRM (Hollywood is notoriously twitchy about this and there is no additional DRM on the Sony projectors that I've heard about...), but they don't have this issue when switching between 2D/3D films. The Sony 4K with Real D setup just isn't designed well from a usability point of view, and many modern multiplexes have shown they can screw up even the most basic of things.
From TFA:
"Sony provides projectors to the chains for free in exchange for the theaters dedicating part of their preshow ads to Sony products. Unfortunately, the 3-D boom took off in late 2009 and Sony had to come up with a retrofitted solution."
Sounds like the bad implementation is due to a quick hack that they've managed to push out to the theaters.
From the article these Sony lenses are retrofits to existing hardware.
The assumption then is that the original lenses were not meant to be regularly changed, which makes sense: Traditionally a theater projector lenses is selected and calibrated for the throw and screen size of the venue...then effectively never touched again. In that situation there's no reason not to have the entire projector effectively "locked down". It's both a DRM issue but also a "don't let the local moron theater manager goof up the finely calibrated projector settings".
3D caught them off guard. Replacing those projectors entirely would be ungodly expensive. There already existed an ability to replace the lens, which technically was all that is required to show 3D. The method to do so was never designed to be easy, however.
So the choices:
1) Scrap hundreds of millions of dollars worth of almost new projection equipment for a completely new "Now with 3D!" design.
2) Supply a replacement lens and instructions (albeit complex instructions).
From a business perspective it's an easy choice. Don't blame Sony, blame the non-sense that is the 3D fad.
My
How about explaining why the picture sucked at my local cinema before this 3D craze took off?
Funny may not give karma, but +5 Informative never made anyone snort coffee out their nose.
I saw Thor in 3D and was really distracted by the poor 3D. I was still charged $12.50 for the privilege of not enjoying the show. Now they can't be bothered to get back to 2D correctly? The local theaters won't be getting my money again soon.
Not only that, but the advertisements have just become absolutely insane. I made the mistake of showing up to a movie on-time recently. And for the low-low price of a $10 ticket and $6 popcorn, I was treated to *20 minutes* of commercials and trailers (not including the slideshow at the beginning). After watching my second car commercial, I realized that I was giving up on theaters entirely. It's bad enough I have to skip through 6-7 trailers on every blu-ray I buy.
SJW: Someone who has run out of real oppression, and has to fake it.
Gee, so on top of the projector problems, I have the various annoyances from people not behaving properly in the theater, possible sound-quality issues, and an overall sub-par experience. Or I could just wait for it to come out on DVD, and watch it at home, where I know the quality of the TV, DVD player, and sound system. And I can pause it if I need to take a potty break.
So what's the benefit to me for seeing it in the movie theater?
(And no, 3D is not a benefit because my wife gets splitting headaches from watching 3D movies).
Tho I wish the article went into more detail about the issue also how to tell the difference between a movie being shown in 2D with a 3D lens and a just naturally dark source.
"They’re not doing that, and there’s an easy way to tell. If you’re in a theater playing a digital print (the marquee at the ticket booth should have a “D’’ next to the film’s name), look back at the projection booth.
If you see two beams of light, one stacked on top of the other, that’s a Sony with the 3-D lens still in place. If there’s a single beam, it’s either a Sony with the 3-D lens removed or a different brand of digital projector, such as Christie or Barco."
If Slashdot were chemistry it would look like this:Cadaverine
So, let's recap again:
Home theatre:
- Better sound (always in the sweet spot)
- Better, cheaper food
- Alcohol, if inclined
- No cell phones
- No lines
- No noisy neighbors
- Can pause for bathroom breaks and food refills
- More comfortable seats
- and now better picture
Cinema:
- New releases available immediately
- Can go with large group
- 3D (I already wear glasses, so this isn't necessarily an advantage)
HT costs a lot up-front, but once you have it, you'll use it a lot - especially considering it works for TV and gaming. (My setup would take about 125 cinema trips for two to break even)
I've actually given up on theaters, and watch movies at home. Too much noise, smartphone glare, impolite people...
On one of my last outings, someone actually smoked a joint, which at least was fun, and quite in the spirit of the movie. Then he started to loudly get into the film, which was also fun, especially since the film was quite bad.
The Cloud - because you don't care if your apps and data are up in the air.
That is one blessing about Austin: The Alamo Drafthouse.
No kids (except clearly marked "baby day" shows.)
Real beers on tap.
People yapping on cellphones get escorted out.
People texting get escorted out.
And who cares about focus after 2-3 brews anyway.
When that happens, leave the movie, go to the manager's office, pound on the door, and raise a stink.
I don't even skip trailers any more. Got myself a copy of AnyDVD HD and all my Blu-Rays go straight to the hard drive as a feature movie. I'll watch the Blu-Ray once for special features, they're rarely worth it though, and even then... I can rip the out-takes as well and not have to dick with the annoying menus and trailers and crap on media that I paid to have available any time.
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Almost all new movies are shot with digital cameras. The image is sometimes post-processed to make it look more filmish. Using a film camera now is a special setup for a special effect.
We've got some of those theaters here in Denver, too. It's nice. The only problem is half the seating is barstool-style, which doesn't lend itself to movie watching.
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I've had missing channels, missing sub-bass (with everything turned up to the point of clipping to compensate), and one all-night film festival where the projectors were 4K, the source was BD, but everything was sent via 480p (i.e. one device in the chain had been configured incorrectly). What really pissed me off was that I actually went to the trouble of finding someone to radio the projection room and tell them both what was wrong and how to fix it, and have them do nothing.
why passwords and such are needed to change the lens and how was it set up like that?
The 3-D lens is mounted inside the case. The password is needed to allow you to open the case, because once the case is open you could get at the digital signal and steal it.
Why they coupled these is a small mystery, the most likely solution to which is that Sony's engineers did what was easy to implement instead of what was easy to use.
Yes. The technical reason is called "Sony DRM".
Amen. And now that I have 3D, no need to go to the theater any more for anything. I can wait until shows hit Blu-Ray.
No cell phones. No kids. No sticky floors. No people absentmindedly kicking your seat. No people around you talking or babies crying. No outrageous prices for snacks.
The theaters have done this to themselves.
It's a 2D copy-making port, it's where you attach the camera.
Nullius in verba
I have to admit that I haven't checked the specs of commercial digital movie cameras but can tell you that with most CCDs the dynamic range is way bigger than with film.
If they don't digitize with enough bits, or throw bits away, or the compression is too extreme, you can lose dynamic range.
Almost all new movies are shot with digital cameras. The image is sometimes post-processed to make it look more filmish. Using a film camera now is a special setup for a special effect.
Eh.. you're both sort of right. Your conflict is coming from the words 'usually' or 'almost all'. It's closer to 50/50 with digital gaining every year. It's also fairly common to use both on a show.
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The industry has decided to make this commitment for DRM (harder to copy in 3D theater with a video recorder) and margin reasons (higher ticket prices). The problem is that the 2D versions with the right lens look brighter and, in some cases, much better. The solution is never show the brighter 2D version. Of course, it cost money to change lenses, too. Bottom line, there in no incentive for the industry to go back to 2D anything, except that, maybe, people will not go to see dark screens.
Bob and a duck walk into a bar. The bartender says "We don't serve quacks in here". The duck turns to leave, and the bartender says "no, the duck can stay - it is that quack pretending to be a doctor that has to leave".
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but you're still a quack, and an idiot.
or a successful troll.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
So what's the benefit to me for seeing it in the movie theater?
One benefit is not running the risk of having your friends, who did see it in the movie theater, spoil the big plot twist.
As someone who has actually operated a Sony 3D projector at an AMC theater, I can't believe a post this wrong got modded +5. DRM and lens changes have nothing to do with this problem; the 3D effect is created by an electronic polarization filter mounted on a dowel that swings in front of the projector lens to show a 3D movie. You can release the clamps and swing it out of the way in about 15 seconds.
The real problem lies in the fact that AMC hires the least common denominator to operate movie projectors and pays them barely above minimum wage so they don't do anything crazy like take pride in their product. I got out of there as soon as I could.
The picture quality is often poor too.
Because you don't have a 100ft wide screen with more than 7 channels (movie theaters have many more channels than 7).
I bet you also listen to your iPod rather than going to see a musician live...
Since your technical arguments aren't valid you throw in an ad hominem attack. I guess you're not going for any positive moderations, and that's ok.
Turns out you don't need a 100ft screen if you sit closer to it - like you can in your own home. We have a 108" picture from our projector and it is a better picture than I've seen in a number of the local theaters.
The number of channels is irrelevant if they are not set up properly. Even as recently as a couple of months ago I've sat through muddy sound in a theater. It's not like I live out in the middle of nowhere either, there are a lot of theaters in the area so you'd think they'd want to stay on top of their game to compete with each other.
Pretty much all decent modern surround sound receivers will do automatic calibration - if the theaters did this too, we'd probably be much happier theatergoers. My receiver supports 11.2, which is in fact more than 7 channels, and it wasn't expensive. Our low frequency setup is the envy of our audiophile friend, and it wasn't expensive either.
As it is now, we only go the theaters as a social occasion with friends.
Putting moderation advice in your
maybe i'm weird, but i like trailers. In many cases, the trailers are better than the movie. You see a couple minutes of just the best parts and you get to use your imagination to weave together a cool story. I've often said i wouldn't mind sitting in a theater and watching an hour of trailers. I wouldn't want to pay for it though. If i could do it for free i think i'd find it preferable to seeing an actual movie. Actually i've done that plenty at home by piping hd quicktime trailers to my tv.
This morning a group of us watched Thor & one member of our group who had seen the movie in 3D IMAX said our 2D version was horrible and dark, probably by 33%. We thought this team member was nuts & now this article pops up. Interesting.
They're Sony projectors? So it should be relatively trivial to hack them shouldn't it?
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As mentioned above, the lens changing was probably viewed as a once only setup feature. I'm betting that getting into 'bios' like features on a projector is protected with passwords to keep the monkeys ($10/hr teenagers) from playing the the multi-million dollar projectors and trying to 'fix' them when they need minor adjustments. Changing a lens probably only requires a changing a option from '2d mode' to '3d mode' in a calibration menu, but it is part of the system that is locked for everyone but admins.
Would you, if you were a corporate IT admin, let your end users go into their bios and change cpu clock speeds if they wanted to, or would you lock them out of everything for simplicity sake?
HA! I just wasted some of your bandwidth with a frivolous sig!
And yet if you watch closely you will notice the advertisements are always in absolutely perfect critical focus, but the feature film is inevitably severely front- or back-focused,
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I go to the local movie theater maybe once or twice a year, and every time I go I'm reminded why the trips are so infrequent. The 20-30 minutes of advertisements and garbage before the show are bad enough, but as far as I'm concerned, digital cinema looks like crap. It's a jagged, aliased mess that's nowhere near the clarity of good film, there's enough ghosting to be a distraction, and I swear I've seen what looks like compression artifacting in fast action scenes that are heavy on red/blue. And now you have these dumb brightness issues. I can get lousy picture quality in the comfort of my own home for much less than the cost of a movie ticket. Plus I can hit the pause button to get up and pee.
Funny, because according to the article and a projectionist that actually offered his real name instead of posting anonymously, it's because of DRM.
So why aren't theater personnel simply removing the 3-D lenses? The answer is that it takes time, it costs money, and it requires technical know-how above the level of the average multiplex employee. James Bond, a Chicago-based projection guru who serves as technical expert for Roger Ebert's Ebertfest, said issues with the Sonys are more than mechanical. Opening the projector alone involves security clearances and Internet passwords, "and if you don't do it right, the machine will shut down on you." The result, in his view, is that often the lens change isn't made and "audiences are getting shortchanged."
That's right, according to James Bond, it's due to DRM.
...OK, so maybe saying "I'm taking the word of James Bond over someone who's anonymous" isn't quite the best way to phrase things, but well, that's really his name.
Plus it's entirely possible you're talking about a different model of Sony projector, since this apparently affects only Sony projectors that were originally 2D-only but later retrofitted to be 3D.
You are in a maze of twisty little relative jumps, all alike.
Maybe a little off topic, but I got really annoyed the last time I went to my local theater because of this latest outrage: "new" "XD" theaters that charge a couple bucks extra for floor-to-celling screens and slightly larger and cushier seats.
The funny thing is, the screen only seems so big compared to the other ones because it's the same size as they were 25 years ago before they started cutting up the theaters into the tiny sizes they are now. It's the same with the seats. They get smaller and harder for a couple decades, then suddenly someone has the bright idea to revert to the old sizes and charge extra for them.
"When that happens, leave the movie, go to the manager's office, pound on the door, and raise a stink."
Fuck that, don't go to the theater in the first place. Sharing space with a bunch of screaming ghettoids, paying too much for crap food, and worrying about my ride getting broken into isn't worth it.
I can't hit Pause when I need to shit, my fridge isn't handy, and there is nothing compelling about a theater experience.
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
I go to movies. I like them. I no longer though go to movies near my home.
I drive 30 mins to get to one of these theaters.
I get there on time. Get an assigned seat. No commercials. A few good trailers. Small theaters.
Respectful people and Ushers that give a shit.
30 min of driving and a few extra bucks and suddenly I like movies again.
Why is it so hard to only have politicians for a few years, then have them go away?
Like most good social experiences, this is way more common in places other than America, especially Europe.
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You weren't in my house last night when Netflix had a system outage.
They're going to frame my emails if they ever see them.
sed -e 's/manager/mayor/' < mypost.txt
HTH
I worked concessions at a theater in Dallas in 1981. The professional projectionists went on strike, so they trained me and other popcorn servers the minimal amount to keep the movies going. I don't remember the details, but 6 months later we became the permanent projectionists and the pros were not seen again. That is the level of concern management gives proper projection.
We still had to swap lenses and aperture plates depending on the film format. It was a simple mechanical release for the lens. I don't know why DRM would require something different for that task. Either Sony screwed up in a fit of paranoia (never!), or the current group of minimum wage projectionists just don't have the necessary training.
Its true, thought it must be said that digital is far more averse to highlight clipping, whereas film has a bit of a soft knee where it doesn't clip so harshly and abruptly. Much better shadow detail with digital however as well as a much wider range overall.
zosxavius photography
Totally. Now, with the need to hype every movie to the max, they wreck the experience of actually seeing the movie by including all the best scenes in the trailer.
Sleep your way to a whiter smile...date a dentist!
I went to see 'The King's Speech" (PG version) at the AMC in (undisclosed Southern California Suburb) Most decidedly and mercifully NOT a 3D presentation
The preshow commercials were running a little dim. At first I thought this was just the 'video' projector running the HD commercials before the show. I took a peek up in the booth and sho' nuff the polarizer assembly for the 3D is parked right in front of the cinema projector lens. It's a big rectangular glass in a sturdy frame - you can't miss it. I go and mention this to ticket taker up front, and I see some of the ushers poke their nose in theater - not the booth. No dramatic improvement.
It's not even as if this projector was bouncing between multiple movies. Is it too much to have someone check the rig - just once - at the start of the day?
That's a retofit method, used on 2k projectors. Projectors such as he SRX-R220, which is a 4k projector, and one that I have used, has a twin lens system that splits the 4k image in to two 2k images. Each lens have their own circular polariser so you loose brightness, as the image has been split in half each lens has to blow up the image to fill the whole screen, so you loose brightness again. When you sum up left and right lens on the screen, the brightness is increased. When it comes to 2D projection, they are not changing the lenses, and only one of the lenses is used, so you get a dull image. If they switched to a 2D lens, the brightness would increase.
When switching to 2D, you get 60% more brightness because you have no polarisers straight away, plus more brightness as the focal length is shorter, and the screen is silvered rather than grey or white like old cine projector screens. You actually go the opposite as it is too bright. The projectors colour space will also need recalibrating because the polarisers have a slight tint. This is nothing hard as they can be stored as presets.
I never recall any passwords being required to change a lens. Only time I have know there to be encryption is with the DCP files that store the film, the keys have to be sent remotely from the distributor to the local server at the cinema.
Trailers belong at the end.
I've noticed most of those problems are gone if you go when the place opens during the week and find somewhere cheap, I pay $5 ($7 for a 3d) and it feels like I have a private screening. Sometimes the movie is a little late though (I talked with one of the managers about it on my out one day and he said they wait a max of 10 mins if they have less than %10 of the theater is sold). Then you can go to lunch afterward and bypass the concessions entirely. It's also got to see if new movies are worth it (usually reviews from average people are online by Monday after a movie comes out on Friday.)
Anything can be found funny, from a certain point of view.
It's not "digital projection." It's TELEVISION.
Oh? Did they leave the 3d lens on the video stream and forget to remove it for the 2d lens for streaming 2d movies?
Attention... all grammer nazi"s! Is they're anything; wrong with: my post,
In the cinema's I go to I get a full screen message that I can text to a number (with a predefined message format) to complain. Discretely, anonymously and direct. Supposedly the manager looks whether it's a real one and if it is (s)he removes the disturbance from the theater / haves the problem fixed.
I have never needed it.
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
Also, I'm not sure how you'd be able to determine whether the `poor picture` problem was caused by 3d filters as opposed to whatever's been respsonsible for poor pictures for the last 35 odd years I've been dragged to see a movie. The quality always sucks! Why doesn't text stay still; why does it have to jump around? Why is the film always scratched? Why does it go out of sync with the audio? Aren't these all problems which were solved in the 1930s?
If they would just get the premium monster cables, it would look so much better.
Or you could just stop going to the movies in bad parts of town.
Back in the day when I was a projectionist, the lenses heated up and required refocusing a few times during the movie. If the beginning is in focus and rest not, the projectionist started the show, focused (or not), and never came back.
there is a difference between a good movie promotional trailer and 10 minutes of toilet paper ads. If I wanted to see a bear wipe its ass I would go camping.
To add, many people now look to fix problems via GUI instead of a physical inspection or, in Larry the Cable Guy language, "just look at the darn thing for something that ain't right".
I know it happens to IT people all of the time. They will try to fix things on their desktops by trying different drivers and reloading Windows instead of checking the card or motherboard for blown capacitors or scorch marks (power hit) or checking the power supply for the right wattage. Sorry a 90W power supply is not powerful enough to power your new 1 Tb HD and your new Uber-powerful 4D Graphics Card AND the tons of USB devices to like to plug into your desktop.
If the supposedly trained IT people make that simple mistake imagine the minimum wage plus flunky trying to fix a 3D projector to show a 2D movie. Solving such a problem is beyond their pay grade. The solution is to hire a contractor to train the projectionists. It is a cheaper solution in the long run assuming anyone cares to solve this problem.
>> It's also fairly common to use both on a show.
O, hi Tommy. .
'
Wiseau, confused about the differences between 35 mm film and high-definition video, decided to shoot the entire film in both formats with two cameras side-by-side on the same mount.
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Trailers are fine. Car ads, deodorant ads, soda ads, etc, are not. I remember the first time they started showing those kind of ads in theaters (believe it was back in the early 90's, here in the U.S. anyway) and how the theater chains swore up and down that it was just a one-time promotional thing. Up until then they would just show trailers (and back in the 70's, you might even get a cartoon or short).
Of course, I knew that once they got started, it would just snowball. They've made movie-going such a painful experience that I can't imagine going back. The outrageous prices are one thing (concessions have always been overpriced, and it's how theaters have traditionally made their money--fine). But the ads have gone too far. If that's the only way a theater or theater chain can make money, then they need to find a new business model. Because my home theater can beat that. and if they start forcing me to watch cars ads on my blu-ray, I'll just turn to piracy (then they won't be getting ANY of my money).
And they can shove their overrated, overpriced 3D up their asses too (or rather, shove it up their asses in T H R E E D I M E N S I O N S ! ! ! ).
SJW: Someone who has run out of real oppression, and has to fake it.
Hell, last time I went to a movie, someone totalled my car in the parking lot.
APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
I think in the end you will see the theatres using this system removing it and replacing it with the Real D XL or XLW system which should substantially increase the light output. In case anyone cares, conventional Real D has the projector rapidly interleaving left eye and right eye frames while a filter in front of the lens electronically "flips" between two polarization orientations so the Real D glasses let each eye see only the correct image. The Real D XL and XLW systems work the same way but make use of the light reflected off the back of the filter to augment that which passes through. All of them can be moved out of the way for 2D.
But there are other systems besides Real D and I will now post a summary of what happens in a 3D-equipped theatre when a 2D movie is show. Disclaimer: I do not work on 3D systems but have friends who install this stuff and I have verified this information with them.
First of all just so everyone knows, looking back at the projector and seeing twin beams of light does NOT automatically mean it's a Sony projector with a 3D lens. There are other systems that create two beams of light such as some other versions of Real D and Digital IMAX.
Real D with the simple "Z Screen" in front of the lens: Easily moved out of the way for 2D.
Real D using the XL or XLW optics used for larger screens: This can be removed or slid out of the way for 2D. There is even a device that will move it automatically. However, even if left in place when turned off it decreases brightness just a little.
Real D using the split field lens (only on Sony projectors): Generally requires a technician to remove and replace BUT the polarizing filters can be removed and replaced by theatre staff---if company policy allows it. Removing them increases brightness on 2D shows.
Master Image 3D: This is a spinning filter wheel in front of the lens and will move down out of the way for 2D.
XPand 3D: This system uses LCD shutter glasses so the correct eye sees only the proper frames which the projector is interleaving. 2D presentations project normally and there is no dimming of the 2D picture. There are no filters except the shutter glasses which you won't be wearing for 2D.
Dolby 3D: A small filter wheel inside the digital projector moves out of the way for 2D which then projects normally.
True Film IMAX: 2D shows run on one projector as usual. No change in brightness.
Digital IMAX aka Fake IMAX or LieMAX: This system uses two separate projectors side by side. When running 2D, the polarizing filters move out of the way automatically. Both projectors are still in use for 2D presentations so there will still be twin beams of light.
Technicolor Film 3D: The 3D l
Having spent an insane amount of time in bear infested forrests I can tell you that you are more likely to see a bear wipe its ass at the cinema.