CIA: Constant Image Area - Page 16

LilGator, like you, I'm trying to do my homework before deciding how to proceed. Thanks for the information; it's very useful.

lol!!!

Yeah, I want to know too.

What have you done to try or prove any of what you say? Just what exactly are your credentials other than being able to say "nyah, nhay, nyah" louder and more often than anyone else?

I am so sick of you doing nothing but empty talk. I don't follow many threads here but just noticed you talking the same S**T in another CIH thread (one you didn't start).

Homework? Let me know when you pass from the "simple math and childrens coloring books" to actually doing a class project where you make something.

In the time you've been arguing this, I have gone from (no exaggeration) giving up on the whole idea of CIA to:
- rethinking it and calculating the max size (10.5' wide) for a very tight space. I'm ashamed that it was this thread that made me try and that I supported you at first.
- talking on the phone with several forum members, almost all CIHers (including several who posted on this thread), who were actually nice, polite, and happy to give their time and advice...amazing how well common courtesy works.
- taking apart, recalculating proper screen radius and rebuilding a torus screen frame (airtight box, compound curve, vacuum fan to pull to exact curve)... not NASA, but lets see you google and paraphrase that math for us
- ceiling mounted my PJ with an adjustable mount and made a ventilated hush box for it
- mounted the anamorphic lens with a homemade transport
- shopped screen materials, visited other members HTs to evaluate screen materials, talked with Stewart Filmscreens, scored some out-of-production high gain screen material, and ordered a custom size to fit the frame
- repositioned and re-equalized my speakers and audio
- designed and nearly completed an adjustable 4 way masking system (try that on a compound curve, keeping the masking within a cm of the screen without touching it)
- with just me and an unemployed handyman-carpenter and no AV professionals
- while working a full time job in the ER
- and I made lots of mistakes I've had to rethink and correct...successfully, so far (knock wood)

When you graduate from grade school and actually set foot in a lab, get back with us.

You've presented some good points, then ruined your credibility by acting like a middle school whiner and crying that your "presentation" shouldn't be the issue. But so far all you seem to have actually done is discover that the zoom button makes the picture bigger and smaller...that and somewhere in the last few months you discovered the "smile" icons.

BTW - I make no claims at being an CIA master either.

Sounds like you've successfully implemented the system you wanted, and it sounds great. Be sure to post pics for the other CIA folks we haven't scared off

non productive posts removed

Not that I didn't believe, but I wondered if it would make a difference using 2.39 instead of 2.35. Perhaps not unexpectedly, it turns out that the screen ratio would be very similar, 2.06 instead of 2.05.

In other words, starting with the width you want for 2.39:1, the height you need for 16:9 to keep the same area would be 1/2.06 of the width. At least, that's what Excel tells me.

And to keep it in perspective, for the 100 inch width screen, the height difference would be less than half an inch out of almost 49 inches.

It doesn't really make any difference (exact area not important), even a 2:1 aspect ratio would be fine. In fact that is what PMI uses in their heigh end CIA systems.

PS people take constant height, constant width and constant area too literally. There are usually exceptions.

I've read this entire thread (please mail my purple heart to me...) and found some useful information.

One question, though, I haven't seen addressed. In my upcoming theater room, I have an unfortunate constraint: I have a patio door directly behind where the screen is going to go. Relocating the door is not an option, so my next best solution is to use a roll-down screen.

I was planning to use a 2.35 motorized screen with masking panels for 1.78 and 1.33, but then I was shown the PMI 2.0 concept, which was also mentioned in this thread a few pages ago.

I did some extensive testing of my own (*) and concluded that the PMI 2.0 approach (CIA-like, but with smaller image sizes for SD content) has a lot of merit.

I'd like to do this type of setup at home, but to do it properly requires true 4-way masking with variable size in BOTH horizontal and vertical dimensions. There are motorized screens that do variable masking of the image height, but for width, all the screens I can find can only select one or two fixed widths by lowering curtain-like masks.

My question: has anybody found a way to do variable screen-width masking with a motorized screen?

One possibility would be to use drapes. This would be a bit of a challenge in my situation because of where my left and right speakers will stand, but perhaps I could make something fly, especially if I used a lightweight masking material rather than heavy drapes for this purpose.

Any other options?

Many thanks to those folks making constructive contributions to this thread!

(*) In case anybody cares about the specifics of what I tried:
I spent this past Saturday in a very nice theater that is set up for 2.35 CIH with a 3-chip DLP and an ISCO-III. I was also able to vary my seating distance to yield different viewing angles. I brought a laser distance finder so that I could quickly calculate the viewing angle for seating locations that I tried. I found that -- for me -- 40 degrees viewing angle is too much for nearly all content. I found 36 to be spot-on perfect for 2.35 Blu-ray. Meanwhile, although I could watch upscaled DVD at the same size, my preference was to watch it at a somewhat smaller size where the compression artifacts of DVD were not as visible.

As well, I found that if I were to use a CIH screen set up at a size that I found comfortable and enjoyable for 2.35, most 1.78 content looked fine to me on the CIH screen, but some would have benefitted from being bigger. IMAX is a prime example, but Planet Earth and One Six Right (HD-DVD) were both also more enjoyable a bit bigger. And of course The Dark Knight....

In summary, I could do just fine with a 36-degree 2.35 CIH screen with masking for 1.78 (and maybe 1.33 if I really go crazy), but it would involve a compromise for some content. What kind of self-respecting HT geek would I be if I didn't at least try to do the no-compromise solution?

By the way, to the person who commented a little while ago about how he was surprised by how big a difference masking made -- I second that! In my testing, I was also able to open the masking system wide open to see what it would be like to just forego masks, and even with a very good projector in a fully light-controlled room, the jet-black masking really adds punch to the image.

That's about all I can think of.


I think you'll find if you read through the thread, that most of even us most die hard CIH people, agree that IMAX should be larger. The issue is, how much content is that? I've got 1 IMAX movie and I haven't watched it in years.

I suppose If I were to build for IMAX, within the limitations of cropped-for-Blu-ray, 1.78:1 IMAX) I'd have a 16:9 screen as wide as my 2.35:1 screen and leave it masked down to 2.35:1 all the time. Everything but IMAX would be CIH, and then I could open up for IMAX. Though this would probably require a VC lens or the shrink method.

That would retain everything in the proper proportion, scope movies bigger than TV, and IMAX bigger than everything, each as they're intended to be. But is it worth it, for one or two IMAX movies? And as for TDK, well, that's an odd one, sure I don't have the IMAX experience, but then again, I didn't when I watched it in the (not IMAX) theater either.


Unless you've got a IMAX ratio screen (and a source for uncropped IMAX content at a quality better than DVD), you're going to have to compromise something. IMAX is very hard to do well at home, arguably impossible since you can't get native 1.43:1 IMAX content with decent quality (ie better than DVD).

HT is all about where you draw that line.

Thanks for that. Do you find that you enjoy BD and DVD at the same size, or would you rather see DVD at a somewhat reduced size compared to BD if that were feasible?

You raise a good point about IMAX -- it's definitely not 1.78 natively. I have a handful of titles, and I'm a bit of a space nut so I do watch some of them from time to time, so it'd be nice to make it big, but it's not the end of the world if not.

I believe I have, although my system is being put together as I write this. Whether it works great remains to be seen. But I have no particular reason to think it won't work.

I'm employing 4 way automated masking, because I want to be able to vary my screen size and shape. 4 way automated masking from the screen manufacturers is hideously expensive, and even some $18,000 4 way masking systems aren't as flexible as I'd like (or as you'd like, it seems).

I didn't want to go the full DIY route because I'm not a handy-man and it's clear automated 4 way masking is quite a trial, even for the DIY guys.

So I decided to combine two professionally made products to create my 4 way masking. For horizontal masking - varying the image height - I'm using the Carada Masquerade Horizontal masking system:

http://www.carada.com/Masquerade-Masking-System.aspx

As you can see Carada will soon be offering a vertical CIH masking system.
However, when it comes to creating motorized four way masking, it's typically much easier to come up with a solution for the side masking (motorized curtains, etc) than it is for the horizontal (top/bottom) masking. Which is why I'm buying the Carada horizontal masking system.

For vertical masking - the side masking - I searched for a company offering automated curtain systems, preferably that would allow me to program pre-set stopping points for various image widths. Then I found Goelst, who offer just what I was looking for: Their 6200 track system is remote controlled and offers up to 5 programmable stopping points for various image widths:

Goelst:

http://www.gsoft.nl/index.php?id=18

But then I noticed they also do a roller panel system, using the same motor:

http://www.gsoft.nl/index.php?id=15

Video of roller panel system:

http://www.gsoft.nl/index.php?id=35

So I decide on using the roller panel system instead of the curtains for side masking. I can get a nice clean edge with the roller panel system and a nice clean look over all. Also, the panels stack behind each other, to either side of the screen when opened up, taking up little space to the sides of the screen. (I'm going to modify the edge of the inner side masking panel to orientate it closer to the screen surface, to avoid shadowing).

So the combination of the Masquerade for top/bottom masking and the Goelst panel system for side masking will make for 4-way remote controllable automated masking.

My screen will be as wide and as tall as I can fit in the room - in my case I'll end up with a 124" wide by 61" high viewable screen area - and the masking system will alter the image shape and size as I wish, while I zoom to whatever size I wish depending on the movie, source quality, my mood or whatever. Always fully masked.

As far as how it will operate: Both the Masquerade and the Goelst system offer a continuously adjustable travel so I can zoom the projected image to the size I wish, and then "jog" or adjust both top and bottom masking to fit the image.

As far as pre-set image sizes go, that's a bit more of a mixed bag. The Goelst will allow the 5 pre-set image widths - 6 if you count "fully open" - which would actually cover most image sizes I might use. Whereas the Masquerade has fewer presets - "open" and "2:35:1" masked. You can have Carada set the 2:35:1 stopping point wherever you want.

So there's the issue of the side masking offering more pre-sets than the Carada top/bottom masking. Personally this is fine with me as I'll be adjusting the masks likely anyway. Having some pre-set image widths can expedite the masking process to some degree: Select an image width, the masks move to that width, zoom the image to that width, then bring down the top/bottom masks to fit. And in fact it might be possible to program more pre-set image heights
with the Carada. The Carada has a "jog" button that moves the masks in 1/2" increments with each push. At least one forum member has found he's been
able to program the Carada to stop at various image heights, using macros on his universal remote to activate the jog feature to discrete numbers of steps.
I'll likely try the same.

One other issue is how projector zooms tend to work: They don't always zoom out proportionately, e.g. the top portion of the image will expand more than the bottom portion. How much this occurs will tend to depend on how much lens off-set you've had to use, dependant upon how centered to the screen you are able to place your projector (the more lens off-set you must use, the more uneven the image will zoom out).

Is it a big deal? In my pre-tests for this system, I have not found it to be so, either zooming with a manual projector or with my new JVC RS20. The JVC has remote controlled zoom and lens shift. I've practiced zooming the image from the JVC, using various tape marks on my wall to see how easy it is to adjust the zoom and image shift to within specific boundaries - as will happen with the masking system. It has been very quick and easy to do so, so I don't foresee any issues. (I've also tested out this "zoom method" on another forum member's RS20 projector on his screen and it was a cinch).

My room is under reno and the screen wall is being rebuilt right now. I have the Goelst roller panel system in hand and I'm awaiting my Carada Masquerade.

Fingers crossed it all works..but it should. I'll be able to give every aspect ratio it's full glory, even including IMAX content, The Dark Knight etc. And the price for the Carada/Goelst combo will come in just under $5,000. Around 1/4 the price of options from the screen companies, and even more flexible than some of those more expensive offerings.

Hope that helps.

(I'll be starting my Home Theater build thread with all the details very soon)

I watch DVD rather rarely anymore actually. Well somewhat rarely. Anything scope I watch in BD, just the way it works out, only DVDs I watch are TV show type things and by nature of being CIH they're smaller than scope movies. Doesn't really bother me having it that large.


I don't want to try and talk you into giving anything up. But we (all of us) tend to get easilly hung up on "small" issues. IMAX gets brought up a lot when talking about the merits of CIH, and it seems to be forgotten just how much some of us really use/watch it.

I agree. The whole Dark Knight issue became blown out of proportion I think. There are compromises in virtually every home theater system, so it's a question of picking your compromises, or at least limiting them to the degree you can.

If you choose an IMAX-shaped screen you end up with a screen that does not "fit" the vast majority of films available, in order to privilege the very few. I don't know why anyone would do this.

Now, in my particular set up I won't feel particularly compromised in terms of the size and shape of my screen, since it will alter it's size. I feel my compromises have been moved more into the expense and complexity, which a lot of people may feel aren't worth the gains.

Thanks for the pointers, Rich, and regarding IMAX I agree completely. My focus for purchased content moving forward is going to be for 2.35 Blu and 1.85/1.78 Blu, but I still have a huge DVD library and I doubt that much of that content will become available on Blu very soon. For this iteration of the theater, I need to factor in DVD viewing.

One other thing: stranger89 noted that TV should be smaller than 'Scope film. I agree with this in most instances. As an example, I had friends over to watch the Battlestar Galactica series finale on my existing 108" 1.78 screen (brought over from the previous house), which in my new room is very nearly the width at which I eventually want to project 2.35 Blu. It was much too big for me! I had a headache by the end of the show.

I think that there is a big difference in how scripted TV entertainment is shot for HD than in how film is shot -- (HD)TV tends to completely fill the screen with action and movement. I hypothesize that this is because they're targeting people with plasmas and LCD's, which is certainly the majority of the viewers. If the screen is very large, this kind of content is uncomfortable for me.

Therefore, I expect that the smaller 1.78 area of a CIH screen would be absolutely perfect for nearly all HDTV. The exceptions might be programs like Planet Earth, and also possibly sports (but I'm not a big sports guy so it's less of a factor for me).

It's with the 1.85 films that I have a bit of concern. One thing I like about the PMI 2.0 strategy is that 1.85 is not as wide as Scope for these films, but it is a little taller. And, DVDs that don't hold up very well at the full 2.35 screen size can be shown a bit smaller where they really look quite good.

That is somewhat in line with what I found when I experimented with various image sizes on my wall. From my 11.5 foot seating distance, I found my comfort level reaching a limit at around 124" wide for CinemaScope, and in fact somewhat narrower sometimes depending on the content. Yet there was 1:85:1 content that I really enjoyed significantly taller than the height they would have been limited to if I stuck with a CIH set up. Examples being Jurassic Park, Planet Earth, HD DVD/Blu Rays like Stanley Kubrick's Full Metal Jacket.

I watched Full Metal Jacket, a 1:85:1 aspect ratio, at about 61" tall (around 124" diagonal size) and it was just awesome. It really put me into the scenery which felt really "right" in that war movie. Like I was there.

Yet if it had been a CinemaScope film at that image height it would have been a massive 143" wide image - too big overall for my comfort at that seating difference. So the standard CIH formula of "find the height you like for 16:9/1:85:1 content and then expand the width for scope" didn't work in my case. Once I enjoyed some 1:85:1 content REALLY BIG it was too disheartening for me to give up the option and stick with CIH.

So...on to 4 way masking and a very tall/wide screen I went.

Can't wait to see your build thread!

Speaking of IMAX ,I saw Star Trek yesterday, what a wonderful film and at 70' it was very engaging. Some of the fight scenes it was almost too big.

Art

Which IMAX theater did you see it in Art?

We went to the NGC Trillium in Grand Blanc. It's a DLP IMAX and the projector seem to have a little trouble keeping up with a few scenes. I would like to see it again in a film IMAX to compare.

Super movie, lots of fun, and perfect for IMAX. And I agree, sometimes it did feel almost too big.

Celebration Cinema in Lansing. This is a film based theater.

Art

Thanks Art.

I have read through a lot of this thread, and I am thinking CIA is the way to go for me. Is 2.05:1 or 2:1 better?

In my situation, 2.05 or 2:1 is a better situation than 1.78. If both 2.05:1 and 2:1 are both viable options, I think I will go 2:1. 2:1 allows me to make a 3" boarder and catch all of the spill for scope movies. If I were to go 2.05:1, using the border I was planning on building , a fraction of an inch would spill above the border...not a big deal, but I might notice it on Dark Knight IMAX scenes

I am using a Marantz 8600.

I am doing a diy screen. I am going to start by painting the wall black and hanging my screen. Next step is figuring out the best way to do diy masking on the cheap. I might even forgo the velvet from for the moment to make sure I am coming up with something that could include a masking system. My screen is a Doable 1/4" thick hard board. The way I am going to hang it, it will "float" off the wall by about 1/2" to 1" all the way around.

Does anyone know of any diy threads that offer ideas for different masking options?

lilgator

I am in the same boat as you. When i completed my theater a few months ago, I installed a 14' wide 2.40 SMX screen. I watch alot of movies but also watch alot of 16:9 material. Once i got use to watching movies in scope, 16:9material definitely felt like a sacrifice.

DP released a new feature on their Titan Projectors called ILM. Intelligent Lens Memory. Now you can save mutiple lens positions for Zoom, Focus, and Shift. Now that there is an easy way to adjust image area, i am looking at making a screen change. Luckly my Titan Ref can be upgraded. I am sending it off to DP on monday.

I am looking at doing a 2.0 aspect 4 way masking SMX screen. That way my scope material with still remain 170" X 72" but my 16:9 material will increase from 128" X 72" to 150" x 85"

My scope material will still be wider, but my 16:9 material will be alittle taller. That seems like win win to me :0

Now the Gators will never be sacrificed to a smaller screen size again!

As soon as I get the projector back and get the new screen, ill update my room construction forum with pics!

Wow, talk about the big budget way to do CIA

Have you fiddled around a little with different aspects ?
I have done that and as a lot of movies are 1.85 to 1 rather than 16:9 I found them to be too close in width to Scope on a 2:1 aspect ratio.

I would probably be able to live with anything from 2.05 to 2.2 to 1 but I definitely would lean to 2.1 to 1 and above in order to make Scope movies noticably wider than 1.85 to 1 movies.

My first real home theater screen that I got nearly 10 years ago was 2.15 to 1 - I still think that is a very nice AR.

Whoa ccool96. That's an incredible set up you have, and are going to have.
As someone who will be doing 4 way masking and a zoom method, I drool over the SMX 4 way masking system.


That's the point I keep bringing up, which virtually never gets brought up when the CIH devotees give the lists of reasons to do CIH. The mantra is that all you have to do is base your CIH on a satisfying 16:9 screen size/height and then a 2:35:1 screen based on that height should leave you with no compromise, since you start with a satisfying 16:9 image size.

But human perception just doesn't work that way (at least for most people).
Once you get used to a larger image - in this case your scope image - your 16:9 image is going to feel smaller than it otherwise would have if you'd stuck with 16:9.

I mean, you have a HUGE screen with a 16:9 image of 127 inches wide and about 146" diagonal. That dwarfs the size of most people's 16:9 screens on this forum. And yet even a 16:9 image THAT big feels unsatisfying to you once you introduce an even larger image to constantly compare. Art on this forum has stated similar things, and he has a mammoth 2:35:1/16:9 image as well.

That's why I say it's not simply an issue of how big your screen is, or how big or tall your 16:9 height is, the comparison effect will come into play no matter what.

I think you'll have this solved, albeit in an expensive way, with your new screen size/4 way masking.

I haven't got my screen up but have for the last year simply zoomed the image to whatever size I wanted on my wall. Ever since I started doing that I've never once experienced issues with image size, or the "comparison effect" because I can always make any AR the size that feels right.

Hi Cool,

Beautiful looking theater.

Which row of seats do you usually sit in?

Gary