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D-Cinema Projector Aspect Ratio

post #1 of 36
Thread Starter 
Hello everybody,

I'm sure this has been answered somewhere, but how do DCI Cinemas deal with the different aspect ratios? Do they use anamorphic lenses or what?

Just curious but thanks in advance

post #2 of 36
Digital Cinemas were using anamorphic lenses unitl nec and barco started the servo zoom option. Now both methods are used (dependent on lens td/geometric match to the venue) Also some theaters are just dedicated to a primary aspect ratio (cinemascope/flat). With servo zoom lens and infinite option of aspect ratios is offered. At least one HT projector manufacturer claims to be the first to offer limitless aspect ratios in CIH. I wont comment on that one.
post #3 of 36
Thread Starter 

What is a servo zoom lens? How does it work? What makes it different from a regular or anamorphic lens?


post #4 of 36
servo zoom is a motorized zoom that keeps focus sharp. this involves a dynamic adjustment of focus as you move through zoom range.

it is important to recognize though that this is not the same as a zoom lens that has a power feature.

In order to do this in such a way that it is meaningful for a proper implementation, the zoom motor has to be extremely accurate and you have to be able to instruct it to go to exact values. not as easy as it sounds in a projector implementation.
post #5 of 36
Thread Starter 
Wait, so if I understand this correctly, it is a very accurate zoom memory lens, essentially with autofocus?
post #6 of 36
Yes it is a smart lens.

The Barco (nor any DCI smart lens)does not have autofocus, whatever you save in the memory can be replicated accurately, also if in the process of saving that memory you took your lens for a wild ride (say shifting onbe way, the over-correcting the other way, then de-focussing one way and going through focus in the other direction) if you save that that is what you will get.

Depending on the projector positioning very little focus adj may be required. These lenses have excellent DOF (depth of field).

I personally see softening when an anamorphic lens adapter is used that is absent with the servo zoom lens system, in addition anamorphic lenses reduce ansi contrast by 20-30%.
post #7 of 36
if your primary lens is say f5.6, you would have more light loss and great depth of field and excellent contrast.

If you slap a low fstop lens like f1.4 in front of it (an anamorphic lens wants to minimize light loss, so the low fstop would be a compensation, and then means a loss in contrast) then there will be a downside.

Not all anamorphics suck. in the circumstances we are referring to, there is a downside that COULD be a no go with the system. the upsides are brighter image, more resolution and far less control needed. So for another install with a more forgiving primary lens... then an anamorphic may make total sense.

post #8 of 36
Originally Posted by Dizzman View Post


I know that is sort of your mantra, I greatly differ. On a clean slate design there sure is a better solution, less flexible but always truer to the eye. Servo Zooms.
post #9 of 36
peter... you can be a broken record sometimes.

And while that proj is a good one, there are many who feel that sacrificing the resolution and the brightness is an unacceptable tradeoff.

You feel that it is the best for you, why cant you accept that it is not the best for all.
post #10 of 36
Because I am intimately familiar with this projector, at this time there is no better projector for HT, there may not be one even half as good (speaking about the highly modded one and not the stock unit). The resolution issue is mental masturbation at this point, it would soften things up quite un-nicely, thank you (not). The brightness issue (even with the 6k-1 cr mods you can still spec. in a different lamp). You know my opinion (anyone talking anamorphic for this projector -did not plan his installation well, if they insist on anamorphics I say they are idiots-it would kill the sharpness). You know Barco's opinion (this projector is designed to be used WITHOUT anamorphics. You may have read wolfgang, which is sometimes too politically correct across multiple projector vendors but in this case agrees with me in this issue.

The isco is a visual patch to soften things up PERIOD. Time to move on.
post #11 of 36
for that projector, anamorphic lenses that are commonly available are on the most part an inferior piece of glass.

So when you take a very high quality primary, and stick a lower quality secondary over it, then yes, there is a drop. just like port glass issues. as it is a hunk of glass, it behaves as a secondary.

If one got a hold of an anamorphic lens that was of sufficient quality, then there would not be anywhere near the drop you proclaim.

Peter, my issue is with your uninformed ranting when you are just plain wrong in the context of what you are saying. to say that all anamorphic's rob X% of contrast/light/secret sauce... whatever is incorrect. if you understood the physics of what was going on, you might be able to understand why it is simple math that IN YOUR CASE you are seeing quite a dropoff.

You are working with what is arguably one of the best projectors in the world. i will not dispute that as it is a fact. as well you have some of the best glass to work with. so putting an "HT" secondary in front of it will LOGICALLY reduce quality.

You keep talking like there is some secret magic that only you understand. there is no magic in any of this. secret sauce is how mods are made in some cases, the goal, the 'what they are affecting" is not secret.

you say that the light dropoff does not present an issue for YOUR INSTALL... guess what, somebody with an even bigger screen, that may not want to go to a bigger lamp (heat/power/etc) may find the 30% wasted light unacceptable. and guess what, if they really went digging and found an anamorphic lens with much higher optical quality, they would not see what you see. because it would not be happening.

Honestly peter, learn some of the physics behind these things. the optics can be pretty fascinating and give you much deeper insight as to what is going on.

To be VERY clear, i am not an optical engineer. i am just a video guy. and i was big into photography years ago. but knowing some of the basics make the picture far clearer as to what is going on. i do not claim to know much more than i am talking about here. but when you talk about projectors... we really are talking about a reverse camera. so the optics are king. Just like a speaker is a backwards microphone. get a clear high level understanding of how one works, and the other becomes pretty clear as well.
post #12 of 36
as all know i not "always" agree to peters statments but he was right
about the decrease of picture quality when you use even the
best isco anamorphic lenses.

as i had 1 year ago 2 christie hd6k i can easy test it with the isco lens in front and the other without.

both on the same screen both the same way calibratet and just to
compensate the light one was drop in lamp level 30% down to have
the same lumen at the screen.
who have such a test set up and can see it this way?

its may not day and night but you easy can see that the image with the
isco not looks as good as the pr. without.

i show it to some very knowing people and some
that dont know anything about high end home cinemas but even they can
see the difference.
to prove that may a differece in the 2 pr. are the reason i switch
the set up and cange the pr. but the result was still the same.

i play this days a bit with my new jvc rs20 (my new pr. for my holiday hause)and you can see the decrease there as well but i agree that
the better the pr. is the more you can see a decrease from such a lens in
front of a pr.

for me it was clear.

post #13 of 36

post #14 of 36
I work in D-Cinema and I have to add a few "facts" here as well.

We have several installs in my area, and some use an anamorphic and some don't. There is no loss of resolution either way really. DCI specs the data to be 2048 x 585 square pixels for "scope 2.39" and 1998 x 1080 square pixels for "flat 1.85" Yes, it is wrong that scope has less image data from the server, but that is how it is. Basically, we are stuck with pillar boxed flat and letter boxed scope. Mapping this as true pixel to pixel and using a zoom lens to fit the screen will give the best result as long as you have enough light. When the 1.25 anamorphic is used to allow the use of all the pixels the image has to be stretched from 858 to 1080 pixels vertically. Even though it is using more pixels, it is no longer a 1 to 1 match so there actually a loss in resolution. There are two reasons an anamorphics is still used in some D-Cinema installs. The first one is the limited zoom range of the lenses. In many cases, a single lens will not go far enough to change from the flat size to the scope size of the screen masking. It all depends on where in the zoom range you need to be and if the screen has moving sides and or top/bottom. The second reason is light outout for a very wide scope screen. We have a couple installs over 70 feet wide and using less than all the pixels with a 6,000 watt lamp is still not going to cut it. I also think the widest angle lens might not fill the width anyways, so the anamorphic is needed. Even the very best anamorphic is not as sharp though, but the tradeoff is just needed in these cases.
post #15 of 36
cinemas are made to satisfy the everage joe that visit a cinema
and there target is to make money.

for us crazy hig end video people there are other targets and the biggest
target is to have the best possible picture quality we can get.

this is not possible with a anamorphic lens.
holywood ONLY tolerate such lens as they not like it for many reasons that are discussed here (pro and con) for quite a long time.

some infos are also "true facts" and "some" very rare people here
have a cinema unit and some know A LOT about it.
post #16 of 36
I still say wolfgang we welcome GXM to the forum and his very informative two first posts. As home theater nerds attempting to integrate DCI equipment for home use, we will need as many DCI insiders as we can to get to explore the nuances of the better gear. Let's face it, this gear is designed from a totally different perspective than HT gear.

GXM confirms my suspicion that in Movie theater installations/converts the 1.25 isco is used primary to compensate for a poor room to lens match (where only one of the two aspect ratios can be reached). For that matter Christie has created a very high quality wide lens adapter without the anamorphic stretch that is probably a better solution to the problem.

In your other post GXM mentions that active glasses 3D system are slower than the Real D and Dolby 3D, as they cannot do full res 144fps. Is that true Wolfgang? I have been looking at these systems and yes the Dolby with Dual Barco s was very fine. But for a single projector the expand system was the cleanest I have seen in terms of lack of ghosting.

3D Cinema Active Glasses
Primary Features

3D Cinema glasses system is designed from the ground up for use in today's digital theaters:

* A stylish, quality product - one exhibitors will be proud to provide their patrons
* Superior 3D performance without ghosts
* Lenses optimized for viewing on screens of larger sizes
* One size fits all (a smaller size for children under eight will be available)
* Light weight and comfortable
* Fits over prescription glasses
* Rugged and fully sealed - washable in an ordinary kitchen dishwasher
* Quick and easy installation
* Easily moved from screen to screen to optimize theater utilization
* Works with any screen - superb 3D on a standard matte screen
* Can be used in very large and very wide theaters
* Does not affect the use of the theater for 2D movies
* Cost effective - lowest life cycle cost
* Does not require the projector to run at reduced resolution
* Does not require a special projection lens
* Does not require the projector to run at excessive frame rates
* Does not require remedial preprocessing of the video stream. Ghost suppression is inherent in the design of the glasses

Animated short feature on how to use XpanD 3D glasses
AG100 Active Glasses - Specifications

Parameter Specifications
Lens Type Pi-cell LCD
Lens Size 2.5" diagonal
Weight 2.1 oz
Lens Transmittance 29%
Synchronization Method Infrared - 940 nm
Battery A 3v Lithium/Manganese Dioxide coin cell is sealed in the frame of the glasses
Battery Life

* Active Mode, Double Flash (IR signal being received) ˜ 800 hours (˜ 400 2 hour movies)
* Active Mode, Triple Flash (IR signal being received) ˜ 600 hours (˜ 300 2 hour movies)
* Clear Mode (No IR signal) = 8000 hours
* Off = 5 years

Dynamic Range 200:1
Frame Sealed, fully washable. Wash/dry temperature not to exceed +50° C (+122° F)
AG100 Active Glasses - Handling Instructions

Parameter Instructions
Storage Glasses should be stored away from any IR source such as fluorescent lights or be covered so the IR does not trigger the glasses to switch to the on state. The storage temperature should be standard office temperatures as high temperature environments reduce battery life.
Handling The AG100 glasses are generally pretty durable, but the lenses can be cracked if the glasses are rotated around the focal point of the nose piece. When distributing the glasses to users care should be taken to handle the glasses by the frame in order to avoid getting fingerprints on the lens.
Cleaning The AG100 glasses can be washed in a dishwasher in which the water and drying temperature does not exceed +50 degree Centigrade (+122 degree Fahrenheit). If cleaning by hand you can use a standard cleaning agent that is not ammonia based. Windex has an anti-bacterial cleaning product that works quite well. The glasses can also be washed under a faucet using liquid soap and warm water. When cleaning by hand you should dry the lenses using a lint free, soft, drying cloth. (DO NOT USE PAPER TOWELS AS THEY CAN SCRATCH THE LENS)
post #17 of 36
yes i also welcome gmx to the forum no problem but when i read
"I work in D-Cinema and I have to add a few "facts" here as well."
i just like to give him the info that some user here know also a bit and
the target from cinema and high end home cinema are a bit different.

about 144 hz.
do a search and you found unter my posts the answer.
just put "144 hz" inside and you can see it.
post #18 of 36
Originally Posted by CINERAMAX View Post

In your other post GXM mentions that active glasses 3D system are slower than the Real D and Dolby 3D, as they cannot do full res 144fps.

My D-Cinema theatre in Italy will most likely use the XpanD system, I've been given the opportunity to test the AG100 glasses for a few months and they can do triple flash just fine. Problem is, the current 1.2" DMDs can't: there will be a new revision coming out soon, and Christie should be the first OEM to adopt it.

post #19 of 36
the barco dp 1500 and 2000 can do it sice end of 2007 when barco
ship the first unit with a 0,98" cinema dmds (2048x1080).

i runn my barco dp 2000 at 144 hz in 3d with the cristal eye shutter at full 2048x1080 since april 2009 this way see also my thred about the
barco dp 2000 in this section.

the new 1.2" cinema dmds will be out by end off january 2009.
christie will be the first one that use it.
you can order this pr. right now and delivery should be IF there is no
further delay jan/febr 2009.
this new christie can do 34000 lumens as well.
good for 3d
post #20 of 36
Originally Posted by W.Mayer View Post

i runn my barco dp 2000 at 144 hz in 3d with the cristal eye shutter at full 2048x1080 since april 2009

The Cristal eye is only for computer applications, does it also talk to the DoReMi?
post #21 of 36
post #22 of 36
you are the " 3-D Theater Guru "

shutter glasses.
at the ceatec the use it from nuvision but they can use also
other shutter.

i hear that real d(christal eye) have a new system
that drive such shutter without any emitter!

the put in the source some for us invisible marks inside
that drive the new gereration from shutter glasses.

that make some missadjustment impossible as the source tell the
glasses how the have to operate.

nice system and the only way to market such system as the consumers
cant do a mistake.
post #23 of 36
Originally Posted by W.Mayer View Post

you are the " 3-D Theater Guru "

I only claim to be at the trailing blaze of 3D viewing room design, with my new space planning arrangements to optimize 3D angles of view and unorthodox screen designs to augment the 3-d envelopment effect (ie. rear projection Torus). When it comes to the state of the art 3-D technology and systems I deffer to you, herr vorfuhrer.
post #24 of 36
oh wie schön wunderbar
post #25 of 36
Where did i say anything other than putting a secondary of lower optical quality in front of a better primary will reduce in lowered image quality (in some areas)

i said that in some installs, the tradeoff will not be acceptable.

If we have full control and can put the projector inthe right spot so that all needs are met with a dynamic servo controlled zoom, then we will have the best of both worlds.

TO make a claim that all anamorphic lenses will reduce image quality is incorrect.
post #26 of 36
In many of the theatres I have worked in, quality is much more important than the typical multiplex. That being said, if they can do it without an anamorphic, they do it without. I have been in the theatre, looking at the test pattern as the anamorphic rolls in, and you can certainly see a loss of detail and contrast. I won't say it is a bad picture, but it could be better. Putting a digital projector into an existing theatre has many of it's own issues. We are looking forward to the release of several new lenses that overlap the zoom ranges of the original 4 we had before. That will allow the removal of the anamorphic in many sites where we would otherwise have had to change the prime lens between formats. The very wide screen sites though are still out of luck, either on focal length or light output.

34,000 lumens, very nice, but is that at 100% on a new 6K lamp or in some silly overdrive like the 28,000 lumens out of the NEC2500?

Using a 1.3 gain screen 72 feet wide x 30 feet high we need 23,300 lumens on the screen to hit the DCI spec 14 fl. But that has to come from only 79% of the chip if done just letter boxed. If the new projector really does an honest 34,000 lumens, we should be in good shape. 34,000 x 0.79 = 26,860 lumens so it should do it. The current NEC2500 just barely makes 14fl with a brand new lamp over driven with the anamorphic.
post #27 of 36
Thread Starter 
So in DCI, do Scope movies use the full vertical resolution of the projector?
post #28 of 36
No just the full horizontal 2048.
post #29 of 36
My local digital multiplex (Cinedigm installation with Christie projectors) has had a problem with "losing" a good portion of the top of the frame when projecting some flat releases. The latest is "Milk", and previously, "Sweeny Todd" and "We Own the Night". Several scenes have the main on-screen characters missing all, or a good part, of their heads. Road signs and other on-screen text is also cropped.

The scope previews before all three films were shifted to near the top of the frame. I have seen other flat releases there, where the scope previews were centered, that did not exhibit any cropping of the top of the frame.

The affected films looked 1.85:1 on the screen, so to lose the top of the frame, some of the sides of the frame also had to be missing, right?

It seems like it would be harder to screw up a flat projection. All of the scope films I have seen there look great. Again, this has not affected every flat release shown there, and has happened on different screens within the same multiplex.

A pixel mapping problem? A Super 35 digital matting problem? My local projectionist has no idea.
post #30 of 36
These threads are the best. I'm loving the info I'm getting. Keep it up guys.

Question: how do you integrate digital projectors, a Barco for example, into a home theater to use with a blu ray player? What kind of connections and hardware do you use/need? Can you use 1080p/24? Sorry if these are off topic. I just want to learn more.
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