View Full Version : Excellent 2.35 article by Tony Grimani
CINERAMAX
05-27-05, 10:01 AM
http://resmagonline.com/articles/publish/article_774.shtml
Excerpts:
Here's the recipe for 2.35 screen setups:
1) Figure out the target width and height for a decent 1.78:1 screen in the room. The parameters should be that the 1.78:1 screen width is 0.55 of the seating distance. This will give you a 30-degree subtended viewing angle, which is appropriate for DVDs. The other parameter is that the screen height dimension (which is the width you just calculated divided by 1.78) should be such that sightlines are good for all viewers in the room. If you need to raise the screen to improve sightlines, make sure that the viewers don't have to look up more than 15 degrees from horizontal.
2) Figure out the total open screen dimension. This is the height that you just calculated multiplied by 2.35. Make sure there's enough room in the home theater for this big screen, and make sure the screen or screen frame isn't covering your left and right speakers. In all cases, I recommend using an acoustically transparent screen material, so that the center speaker can be in the middle of the screen, and the left and right speakers can also be placed behind the screen, if necessary. Typically, I would still leave the left/right speakers flanking the screen, because they need a greater subtended angle than your screen will cover.
3) Select a screen with motorized lateral masking. The masking stops should be, fully open, at 1.85:1 and 1.78:1; 1.66:1; and 1.33:1. You will share a setting for 1.78 and 1.85, which is acceptable because it means losing only four percent of the vertical picture area through overscan in 1.78 mode. In all cases, the picture height remains the same and only the width changes. By the way, the 1.66:1 stop is for some European and Japanese productions that will end up with gray bars on the left and right of the picture if it is transferred anamorphically to DVD.
4) Program the motorized masking for the source material. Typically you will have manual settings, but with systems using film library databases and video servers, you can actually automate the feature. The Gracenote database is one that includes the aspect ratio details you need for proper automation.
5) Select a projector with a 2.35 anamorphic lens attachment. Ideally the lens is controlled electrically and slides in front of the main lens when needed. Right now, Runco makes this feature available on several projectors with its AutoScope lense. Lens attachments for other projectors should be available very soon, including one from ISCO Precision Optics.
6) Select a scan converter that can remap the image to fill out the imaging device of the projector. Most of Runco's better projectors offer this feature, known as CineWide. When the Cinema mode is enabled on the controllers of those projectors, a trigger signal is sent out to the motorized AutoScope lens to move it into place.
7) Program the system automation to control the scan converter, the anamorphic lens, and the screen masking simultaneously.
8) Install and calibrate the projector so that it overscans four percent in the 1.78 and 2.35 modes. This will present a 1.85 picture with the letterbox bars right at the frame's edge.
CINERAMAX, thanks very much! Very good read for all, especially those who are trying to decide about going constant height.
I found #4 really interesting where it talked about using Gracenote to automate electric masking for the aspect ratios. I think this would add the icing on the cake for a constant height setup.
Mr.Poindexter
05-27-05, 10:22 AM
1.66 is most notably the Disney aspect ratio. Maybe there are Japanese and European productions in that aspect ratio, but I don't have any in my collection.
CINERAMAX
05-27-05, 10:25 AM
It is the european film aspect ratio. Movies like the Day of the Jackal, Baron munchaussen, Diva, etc. Also it was known as Vista Vision here I believe.
[QUOTE=CINERAMAX]It is the european film aspect ratio. Movies like the Day of the Jackal, Baron munchaussen, Diva, etc. Also it was known as Vista Vision here I believe.[/QUOTE]
VistaVision was a separate photographic process that allowed for flexible aspect ratios anywhere from 1.37:1 to 1.9:1. Hitchcock shot many of his films in VistaVision, notably Vertigo and North by Northwest.
Vern Dias
05-27-05, 02:56 PM
Actually, the minimum AR for VistaVision was 1.66:1. 35mm Vistavision prints were hard matted at 1.66:1.
Vern
Jay Taylor
05-30-05, 12:12 PM
8) Install and calibrate the projector so that it overscans four percent in the 1.78 and 2.35 modes. This will present a 1.85 picture with the letterbox bars right at the frame's edge.
I was with him until step 8. Would someone please explain what he’s saying here?
CINERAMAX
05-30-05, 12:32 PM
1.85 times .96 equals 1.78. On video projectors he wants 1.85 films to fill the constant height. Thus the overscan.
[QUOTE=CINERAMAX]1.85 times .96 equals 1.78. On video projectors he wants 1.85 films to fill the constant height. Thus the overscan.[/QUOTE]
So why overscan on 2.35:1?
R-S
acksnay
05-30-05, 04:37 PM
Everything gets the overscan treatment. If I read this right, he's not only overscanning the 1.78 and 2.35 aspects, but acknowledging that by calibrating the throw (zoom really, not overscan) so that the top and bottom bars of an 1.85 film spill out of your screen, then by default all 1.33, 1.78 and 2.35 images would also spill over that same amount (4%).
I don't find this acceptable. I'd rather live with the occasional 1.85 black bars than lose 4% of my most watched material. YMMV.
Jay Taylor
05-30-05, 05:34 PM
Thanks Cineramax & Acksnay for clearing that up.
This fall I’m planning on building a constant height theater with a 2.35:1 screen. It’s unlikely that I’ll go for the 4% zoom idea. Any setup procedure that detracts from the 2.35:1 movie experience gets nixed.
CINERAMAX
05-30-05, 05:55 PM
After a glass of wine and some thought , maybe all he is saying that you install the projector so that 4% overscan is possible for 1.85. You could still have it 2.35 optimised, but with a secondary 4% overscanned setting just for 1.85. That is not unreasonable.
After a glass of wine and some thought , maybe all he is saying that you install the projector so that 4% overscan is possible for 1.85. You could still have it 2.35 optimised, but with a secondary 4% overscanned setting just for 1.85. That is not unreasonable.
I was thinking about that part. It seems it would only work for those that keep the lens in place all the time. This would allow different areas of the screen to be filled.
If you take the lens off for non 2.35 you would need to physically zoom the projector to remove the black bars from 1.85
Another way if you take the lens off is to slightly stretch the 1.85 picture vertically to fill 1.78 and have a preset on the scaler. This means you get the whole picture for all but you slightly stretch 1.85.
The black bars aren't really that annoying.
prismasonic
06-03-05, 03:13 AM
Hello,
With the external scaler or HTPC, which have the ability for the variable vertical stretch it is possible to fill the panel also with the 1.85:1 movies. This combined with the Prismasonic H series lens, which has the ability for the variable horizontal stretch from 1.0x (pass through) to 1.33x, it is possible to enjoy also these movies without the gray bars and loss of any information. This same 'true constant height' goes for the 2.00:1 movies, such as Platoon. You don't have to zoom the image, and thus you will also always have the full panel resolution of your 16:9 projector.
The stretch ratios for the scaler and lens for those aspects are 1.05x and 1.13x
Best Regards,
Anssi Leppanen
Prismasonic
Alan Gouger
06-03-05, 01:36 PM
[QUOTE=Tukkis]
If you take the lens off for non 2.35 you would need to physically zoom the projector to remove the black bars from 1.85
.[/QUOTE]
Thats only if using a Vertical squeeze lens. Thats not constant height. You need a H stretch lens for true constant height. Isco or Prismasonic.
You will have to re zoom and re focus ( most projectors are manual focus/zoom ) each time you remove a V lens and that gets very old quick. Unless of course you are using a 16x9 screen but thats not what this forum is about. This forum is for 235:1 screen constant height systems.
Anybody else find this "0.55" of seating distance to be way too small - that gives a 90" diagonal screen at 12 feet (approx 45 x 80).
I'm setting my 2.35 screen up as a 45x106" and sitting about 9.5 feet in the front row.
[QUOTE=PAP]Anybody else find this "0.55" of seating distance to be way too small - that gives a 90" diagonal screen at 12 feet (approx 45 x 80).
I'm setting my 2.35 screen up as a 45x106" and sitting about 9.5 feet in the front row.[/QUOTE]
Me. ;)
ted
Thats only if using a Vertical squeeze lens. Thats not constant height. You need a H stretch lens for true constant height. Isco or Prismasonic.
You will have to re zoom and re focus ( most projectors are manual focus/zoom ) each time you remove a V lens and that gets very old quick. Unless of course you are using a 16x9 screen but thats not what this forum is about. This forum is for 235:1 screen constant height systems.
The way I understand it with a constant height when you take the horizontal lens off to get full 16x9 resolution 1.85 still has slight black bars. When you take the lens off you're back with a 16x9 projector and 16x9 screen with side masking to cover the 2.35 extra left/right.
Am I way off to say this?
Hello Fellow Members
Well after two hours of reading and two coffees and 5 hours since eating, my brain is spinning after reading this thread.
I like the idea very much and after all, is this what we all should be aspiring to. We with out HT are trying to mimic and or improve the experience we received at a movie theatre.
Ok so how about some calculations.
Room 8meters long by 5.5 meters wide
Floor to ceiling height 2.743meters
First seating row at 5.5 meters (from viewers eye)
Second seating row at 7.0
Screen bottom image height(dictated by center speaker) 900mm
First row on a riser 200mm
Second row on a riser 400mm
What size width and height of screen suggested for 2.35.1 constant height :confused:
benthx, you seem to be sitting pretty far away even in the first row. Any chance to sit closer?
Usually for a 16x9 screen 1.5-2.0x screen width is the best. For a 2.35 screen you should be able to sit the same distance.
Depending on your projector lumens and screen gain you will need a bigger screen than normal if you sit that far back.
Alan Gouger
06-05-05, 07:28 PM
[QUOTE=Tukkis]The way I understand it with a constant height when you take the horizontal lens off to get full 16x9 resolution 1.85 still has slight black bars. When you take the lens off you're back with a 16x9 projector and 16x9 screen with side masking to cover the 2.35 extra left/right.
Am I way off to say this?[/QUOTE]
Your correct:)
VideoGrabber
06-06-05, 11:58 PM
PAP asked:
> Anybody else find this "0.55" of seating distance to be way too small... <
I did too, initially, but after some consideration, decided it wasn't too bad a compromise (for multiple ARs). That 0.55 translates into a d/w of ~1.82, for 16:9 content, but 1.38 for 2.35 AR material. That's fairly reasonable for the stated goal... i.e., DVD sources, though with good material and proper scaling, I'd go a bit closer myself (probably an 0.60 factor).
OTOH, for HiDef content, yeah, "way too small".
> I'm setting my 2.35 screen up as a 45x106" and sitting about 9.5 feet in the front row. <
That's a d/w of 1.08, great for HiDef, yet definitely too close IMO for DVD material. But everyone has different preferences, and none are "wrong". If it works for you, it's right. Some folks just don't like that wide a viewing angle (~50-deg), regardless of the PQ. Others prefer the immersive experience, even if there's not enough detail from the DVD source material to support it.
Also worth keeping in mind is that most HTs have several rows of seating, and if the front row starts out too far back, all the rest will suffer. A front row at 1.1 d/w is fine, when there's a 2nd or 3rd row for those preferring a narrower viewing angle. Plus that 1.1 front row at 2.35 AR turns into a much more conservative 1.4 d/w for 1.85 AR films, with a constant-height screen.
We throw a lot of numbers around here as recommendations and guidelines, but it's up to each individual to weigh them against their own visual experiences and preferences.
- Tim
[QUOTE=Tukkis]benthx, you seem to be sitting pretty far away even in the first row. Any chance to sit closer?
Usually for a 16x9 screen 1.5-2.0x screen width is the best. For a 2.35 screen you should be able to sit the same distance.
Depending on your projector lumens and screen gain you will need a bigger screen than normal if you sit that far back.[/QUOTE]
Thanks Tukkis
I probably will move the front row forward by 800mm and the rear row the same.
That will make the first row 4.7meters from the screen.
I went to a few AV stores today and explained the idea of constant height and they just looked :confused: :confused:
Any members with some reccomendations on size? ;)
My brain is struggling with this :confused:
I understand that by removing the anamorphic lens, or by using one with passthrough that 16:9 images fill the 16:9 portion of the 2.35 screen and that you use masking to cover the rest of the screen. Result, a full height image.
I understand that with 2.35 movies you stretch the source image with the projector/scaler to fill the 16:9 panel and then use the anamorphic lens to stretch that image back to it's correct geometry. Result, a full height image.
What I don't understand is how this works with film ratios which fall between 2.35:1 and 16:9, let's say a 2.10:1 for example. How do you get that ratio to constant height with an anamorphic lens? I'm guessing it doesn't actually work at all or that you stretch/crop to whichever aspect ratio (16:9/2.35:1 is closest)?
Mark
What I don't understand is how this works with film ratios which fall between 2.35:1 and 16:9, let's say a 2.10:1 for example. How do you get that ratio to constant height with an anamorphic lens? I'm guessing it doesn't actually work at all or that you stretch/crop to whichever aspect ratio (16:9/2.35:1 is closest)?
You should be able to use presets in the scaler to stretch vertically by different amounts depending on the ratio. In other words depending on how much is black bars.
Not sure about other lenses but the Prismasonics let you stretch from none=16x9 to full=2.35 and eveywhere in between.
[QUOTE=Tukkis]You should be able to use presets in the scaler to stretch vertically by different amounts depending on the ratio. In other words depending on how much is black bars.[/quote]
Yep, I understand that bit.
Not sure about other lenses but the Prismasonics let you stretch from none=16x9 to full=2.35 and eveywhere in between.
OK. A variable-stretch anamorphic lens is the only way I can see how it can work, because you always want the same height. But then how do you control the variable width - you change it each time you find a movie which doesn't fit 16:9 or 2.35:1? Doesn't sound very practical and also very likely to introduce image distortions?
How do those of you with 2.35 constant-height setups handle those films with aspect ratios between 1.78:1 and 2.35:1? And in-fact, what are you all doing with 1.85:1 films? Cropping them to 1.78:1???
Mark
1.85 to 1.78 is just an inch or so - most people don't even worry about it.
If it's a bit less than 2.35 then you just have a little bit of unused screen at the sides or you can stretch it a bit and likely never notice it at all.
[QUOTE=PAP]1.85 to 1.78 is just an inch or so - most people don't even worry about it.[/quote]
So they crop.
If it's a bit less than 2.35 then you just have a little bit of unused screen at the sides or you can stretch it a bit and likely never notice it at all.
You mean you just let the anamorphic lens do the full stretch to 2.35:1 and accept the geometric distortion this would cause?
Does anybody with a constant-height set up correctly support, let's say 2.10:1, ie it would have full height and have some black bars to the sides (which could then of course be masked)? And, if so, how? This is the bit I don't understand.
It sounds to me that the constant-height approach involves a cropping/stretching compromise when the ratio isn't exactly 2.35:1 or 1.78:1 (or smaller)?
I am considering a constant-height setup in my new cinema and just want to understand what I'm getting myself into :D
Mark
Vern Dias
06-25-05, 11:43 AM
Does anybody with a constant-height set up correctly support, let's say 2.10:1, ie it would have full height and have some black bars to the sides (which could then of course be masked)?
Of course we do. Thats the definition of constant height setup. There WILL be bars on the sides if the AR of the source is less than the AR of the screen. If anyone here doesn't meet this criteria, then they not running a true constant height setup.
Now, how you handle AR's that are greater than the AR of the screen, well that's not quite so cut and dried..... :)
Vern
Alan Gouger
06-25-05, 11:49 AM
Mark_H
I see in your handle you mention 12" crt. Is that a FP. I remember Barco had a 12".
Do you have one of those monsters?
[QUOTE=Vern Dias]Of course we do. Thats the definition of constant height setup. There WILL be bars on the sides if the AR of the source is less than the AR of the screen. If anyone here doesn't meet this criteria, then they not running a true constant height setup.[/quote]
Vern, HOW exactly?! This is what I don't get and nobody is telling! :D
Imagine a setup with a 2.35:1 screen.
All DVD images already fill the width of their screen, so if you use a fixed magnification anamorphic lens then *all* such images will be stretched the full 2.35 width and the only way then to maintain the correct geometry is to crop the top/bottom (except for 2.35:1 ratio films which will of course be correct).
The only solution I can see is a variable anamorphic lens. But if that IS the solution, does that mean that every film must be adjusted manually before you start watching the show?
So what is it? Are people using adjustable anamorphic lenses or are they simply living with cropping/geometry issues when the film isn't one of the perfect ratios?
Please put me out of my misery - no more vague answers! :D
Now, how you handle AR's that are greater than the AR of the screen, well that's not quite so cut and dried..... :)
Vern
I assume it will be the old way of leaving black bars top and bottom within the 2.35:1 screen frame?
Cheers,
[QUOTE=Alan Gouger]Mark_H
I see in your handle you mention 12" crt. Is that a FP. I remember Barco had a 12".
Do you have one of those monsters?[/QUOTE]
Alan, yes I have a Barco 812 hanging from my ceiling.
I am now building my next cinema and will be retiring the 812 for something more sigh digital :D
Mark
Actually, another thought...
How do you handle the vertical expansion on non 2.35:1 aspect ratios DVDs?
I assume most people have two memory settings, one for 16:9 (no vertical stretch) and one for 2.35:1 (33% vertical stretch?). Then depending on which type of film you are watching you select the right memory bank and engage the anamorphic lens?
Go on, admit it! 2.35:1 constant-height screens, while looking cinematic are actually a huge compromise!! :D
Grrr, the more I think about this the more issues I find. Looks like I'll be sticking to a 16:9 screen and doing vertical masking for different ratios like I do now with my CRT :(
Mark
It's really simple - unless you have a different screen and projector for each aspect ratio you watch, you WILL have either to stretch the image a bit or live with bars on the sides. A masking system will solve this problem for you. the same is true for any ratio screen you have - not just constant height 2.35 setups.
[QUOTE=PAP]It's really simple - unless you have a different screen and projector for each aspect ratio you watch, you WILL have either to stretch the image a bit or live with bars on the sides. A masking system will solve this problem for you. the same is true for any ratio screen you have - not just constant height 2.35 setups.[/QUOTE]
So I am correct... for constant-height, with anything other than 2.35:1 or 1.78:1 sources, you are forced to crop/stretch the image in order to achieve constant height...
Yes or No?
If YES, that is unacceptable.
With constant-width, you simply mask the unused parts of the image, but at least you get correct geometry with *any* aspect ratio... and without loss of image due to cropping....
If NO please explain so I understand...
???
Mark
Dennis Erskine
06-25-05, 07:59 PM
Go on, admit it! 2.35:1 constant-height screens, while looking cinematic are actually a huge compromise!!
How is that?
In a 2.35:1 system, you use 100% of your projector's available resolution to display a 2.35:1 picture (with a 16:9 system, your 2.35:1 movies use only a part of the projector's resolution and you don't use all the screen height).
In a 2.35:1 system, you use 100% of your projector's available resolution to display the 16:9 image but you don't use all of your screen width.
In both a 2.35:1 and 16:9 system, a 4:3 image will not use all of your projector's resolution and you'll have black bars (unused screen area) to the side of the picture.
Actually, a 16:9 system results in picture quality reduction in two of the three examples whilst a 2.35:1 system results in picture quality reduction in only one of the example (which happens to be the source with typically the lowest resolution in the first place).
Scopeboy
06-25-05, 11:30 PM
Mark, I think in your instance and setup, 2.35:1 is a compromise given how much of your tube face is not utilized. Given that the tube is naturally 4:3, any screen setup other than 4:3 is going to be a compromise. I hate to turn this into a digital vs. CRT debate, but with anything non 4:3, even you can see by the horizontal and vertical numbers, compromises arise. With digital projectors, and then throw anamorph lenses into the mix, you get more resolution with 2.35:1 than 16:9. I believe that is a correct statement. Apples and apples comparisons cannot be made though, everyone has a different setup in here and different preferences.
You guys should be politicians :D
So, Denis, tell me how I display a 2.10:1 ratio film on a 2.35:1 constant-height setup without cropping or stretching the image... and what about a 1.95:1 film, or a 2.25:1 film?
Cheers
Mark
[QUOTE=Scopeboy]Mark, I think in your instance and setup, 2.35:1 is a compromise given how much of your tube face is not utilized. [/QUOTE]
Scopeboy, I agree and I don't intend to use my CRT for a 2.35:1 setup. My next cinema will be digital.
Mark
Gordon Fraser
06-26-05, 04:18 AM
Mark: It would appear to me that in your scenario the lens would stay fixed. You would then need seperate aspect ratio memory banks on the processor or display for all aspect ratio's taller than 2.35:1. Or, as you say, you crop or distort the image. In all cases you use the full vertical resolution of the panel. This motorised lens system sounds like a bit of a cludge to me.
Gordon
Gordon: That is my conclusion too, hence my comment on 2.35 constant-height involving a compromise, ie anything wider than 1.78:1 ratio, except 2.35:1 ratio, will have to cropped or distorted in order to achieve constant-height IF you only use two settings 16:9 and 2.35:1
IMDb lists 6000+ DVDs with 1.85:1 and ~3000 with 2.35:1 and a hundred between those two. So the number of cropped/distorted films in practice is small.
Perhaps that is why nobody with this setup has noticed, or will admit to the issue ;)
Certainly nobody has offerred a direct answer/solution to my questions which suggests to me that the problem is being ignored...
Mark
[QUOTE=Mark_H]You guys should be politicians :D
So, Denis, tell me how I display a 2.10:1 ratio film on a 2.35:1 constant-height setup without cropping or stretching the image... and what about a 1.95:1 film, or a 2.25:1 film?
Cheers
Mark[/QUOTE]
Just when I thought I had it all covered now this???
I dont believe (with my limited knowledge) that there is EVER a perfect set up without compromise
[QUOTE=benthx]I dont believe (with my limited knowledge) that there is EVER a perfect set up without compromise[/QUOTE]
Not with the current software formats.
But now that we have exposed constant-height's deep dark secret ;) we can take steps to improve things.
As Gordon suggested, you could use different memory blocks to shape the image as required for a few more aspect ratios and thus limit the amount of cropping involved.
The question is whether this becomes too cumbersome in practice...
Mark.
[QUOTE=Mark_H]Not with the current software formats.
...The question is whether this becomes too cumbersome in practice...
Mark.[/QUOTE]
Using your own figures it would be "cumbersome" 2 out of every 70 movies. Hard to define that as cumbersome when you could just bypass the lens for those two and watch them letterboxed like you do now.
Allen
[QUOTE=Allen]Using your own figures it would be "cumbersome" 2 out of every 70 movies. Hard to define that as cumbersome when you could just bypass the lens for those two and watch them letterboxed like you do now.
Allen[/QUOTE]
Allen, it certainly seems that way. I think I'd actually experiment with a third memory halfway between 2.35:1 and 1.78:1 (ie full height and squashed sides on the 16:9 panel) - the anamorphic lense then stretches to the full 2.35:1 width but with black bars to the side which are then masked out. This memory block would be used for those very few films which aren't 16:9 or 2.35:1. Any cropping should then be minimal.
Failing that, perhaps the easiest way, as you say, is to watch letterboxed on the 16:9 portion of the screen.
I just wanted to get to the bottom of the issue. Now that I understand what is happening I am much happier about going forward with a 2.35:1 setup.
Cheers,
Mark.
Mark_H, I really think you're having trouble understanding the basic facts here.
Whether you have a 1.33 screen, a 1.78 or a 2.35 the problem is that it won't fit natively the other formats. Simple enough, right? So WHATEVER format you choose, you will have to MASK or STRETCH the others. OK?
If you choose 1.78 then 2.35 movies will be cropped top and bottom (as will the intermediate formats you seem to be worrying about). If you watch 1.33 you'll get black boxes on the sides or you have to stretch to fill.
If you choose 2.35 then 2.35 fills the whole screen (and with a lens uses every pixel of your projector) while 1.78 will need to be masked on the sides (just like a movie theater does, btw) but still uses all the pixels on your projector if you have a pass-through set up.
Now here's the kicker that seems to be sticking you for some reason - any OTHER variable aspect ratio between 1.78 and 2.35 will need masking to the sides that will be slightly less than the amount for 1.78. If you have an automated system that will indeed pose some difficulty if you want it perfectly masked. But guess what, the same thing happens for a 1.78 screen it's just top and bottom masking instead of side to side and actually side masking is a lot easier to deal with because you can just use curtains if you want!
It's really not that confusing. The only hard part is if you want to automate your masking, but it will be equally difficult no matter what aspect screen you choose.
Your hangup seems to be about the stretching/distortion of the image. The only time you ever need to do that with any aspect ratio screen is if you want to fill your available screen area (i.e. not mask, but change the actual projected aspect ratio). Well you -never- NEED to do that, but it CAN be done instead of creating additional masking setups for those FEW odd films. Some projectors can also "zoom" so you use your whole screen without distortion but you will get some cropping then. Again, pick your poision - mask or stretch.
Dennis makes the point most succinctly above - 2.35 maximizes both your screen and projector usage for the majority of films. Even better, IMO is a constant area setup but the masking and zooming requirements for that get even harder to implement. If I had a projector with memory for a power zoom and big buks for a fancy variable 4 way masking system, I'd do constant area in a second :)
[QUOTE=PAP]Mark_H, I really think you're having trouble understanding the basic facts here.
[/QUOTE]
Nope, PAP, I get it... now.
Thanks,
Mark.
Vern Dias
06-26-05, 07:41 AM
Vern, HOW exactly?!
With a scaler or HTPC of course!!! :)
When I had my CRT and 2.40:1 screen, back in the dark ages ;) I originally set up the 15 or so memories required to support all the various AR's out there.
(Yes there are that many)
Here's a partial list: 1.33:1 1.66:1 flat, 1.66:1 anamorphic, 1.75:1 flat, 1.77:1 anamorphic, 2.00:1 flat, 2.00:1 anamorphic (VistaVision, SuperScope), 2.20:1 flat, 2.20:1 anamorphic, 2.35:1 flat, 2.35:1 anamorphic (2.40 if you want to get technical), 2.55:1 flat, 2.55:1 anamorphic, 2.76:1 anamorphic, and lastly 2.35 LaserDisc with a squeeze applied to the LD to 2.20 or so (many MGM scope LD's).
Today, the whole shooting match can be handled with one CRT memory setup at the screens AR or an anamorphic lens added to a 16x9 solid state projector ( preferably a projector cabable of 1080 HDTV).
All scaling and processing is done by the scaler/HTPC.
There are 2 HTPC software DVD players specifically designed to handle this setup, Theatertek and Zoom Player.
Both allow you to define and store up to 10 or more different AR presets, and also allow one click/key zoom to be used. They also allow you to save the AR for each title.
This means that after a preliminary quick look to confirm the AR, I can set and save it to be exactly correct for each title.
After that, any time I insert the DVD and select "Play" the appropriate AR scaling will automatically be selected for that title.
In addition, these players will automatically select your preferred audio track and can also have an autostart bookmark set, so the movie starts at the beginning. No menus, no FBI warning, no forced prevues, none of the ususal DVD crap that studios put at the beginning of DVD's.
This is how you do constant height correctly, never moving or removing the lens, never changing the expansion ratio of the lens, never changing the zoom settings of the lens, all the while maintaining a solid state projectors native "pixel perfect" resolution, or using just a single memory/convergence setup in a CRT.
any OTHER variable aspect ratio between 1.78 and 2.35 will need masking to the sides that will be slightly less than the amount for 1.78.
Correct.
In a true constant height setup, the height is constant and the width of the image equals the height times the aspect ratio.
If I have a 5' high image a 1.33:1 source will be 6.65' wide , a 1.85:1 source will be 9.25' wide, a 2.0:1 source will be 10' wide, a 2.20:1 source will be 11' wide, and a 2,35:1 source will be 11.75' wide.
Vern
Vern, thanks ;)
Finally some details rather than the "it just works" answer I was getting used to :D
Mark.
Of course you still have to mask all those resolutions...
That's the easy part ;)
Mark
Vern Dias
06-26-05, 01:50 PM
Of course you still have to mask all those resolutions
Or Not.....
I have manually adjustable masking, but most of the time I don't mess with it.
I may have neglected to mention the adjustable masking on ZP, which can be saved on a per title basic along with the AR. :) It cleans up the rough or soft edges and other junk that may be present on the edges. That, in combination with the adjustable image positioning works great to center any badly centered transfers as well.
Vern
mhafner
06-26-05, 06:13 PM
But who wants to watch DVDs only with HD available?
Home cinema with 2.35:1 systems becomes fun once there is actually some decent resolution in the source which is hardly the case with Cinemascope on DVD.
So how do we make this work with HD sources? I'm afraid we need the Sony 4K projector plus a flexible scaler to really imitate a real cinema showing Cinemascope resolution at home. Don't we? A 1080p projector works for 16:9 and 2.35:1 (with lens) and 4:3 (with black bars on the side), but not with aspect ratios between 16:9 and 2.35:1 if you want a fixed lens or no lens, but no variable lens. Correct?
Hi Michel,
If the goal is maintain full resolution of the HD source then, yes, you would need a 4k panel.
Without it, any ratio above 1.78:1, excluding the screen aspect ratio, involves a loss of horizontal resolution.
However, given the very small number of titles on DVD (and again on HD) with an aspect ratio between 1.85:1 and 2.35:1 (and how many you in fact own?) you have to decide whether you can live with the loss of horizontal resolution required to support these aspect ratios on a 2k panel.
The most interesting question is how do you approach the 1.85:1 titles, which are the majority. If you crop to 1.78:1 you lose 4% of the image. But if you apply source width pre-squeeze and use the anamorphic lens to stretch to true 1.85:1 you lose ~27% of horizontal resolution. Clearly 4% loss is preferable to 27% but do you actually want to lose any at all... 4% falls easily within the safe area for overscan so seems an acceptable loss in order to achieve a constant-height setup...
A 4k panel is the only way to preserve the entire HD horizontal resolution.
Mark.
If the goal is maintain full resolution of the HD source then, yes, you would need a 4k panel.
Without it, any ratio above 1.78:1, excluding the screen aspect ratio, involves a loss of horizontal resolution.
However, given the very small number of titles on DVD (and again on HD) with an aspect ratio between 1.85:1 and 2.35:1 (and how many you in fact own?) you have to decide whether you can live with the loss of horizontal resolution required to support these aspect ratios on a 2k panel.
For DVD's with ratios in between 1.78-2.35 you can still use full resolution as far as I know. The Prismasonic lenses allow variable stretch ratios. 1.0 being none and 1.33 is 2.35. For those in between I'm sure the lens allows you to go to say 1.12 for 2.0:1 or 1.24 for 2.20.
Maybe I'm thinking wrong here.
[QUOTE=Tukkis]For DVD's with ratios in between 1.78-2.35 you can still use full resolution as far as I know. The Prismasonic lenses allow variable stretch ratios. 1.0 being none and 1.33 is 2.35. For those in between I'm sure the lens allows you to go to say 1.12 for 2.0:1 or 1.24 for 2.20.
Maybe I'm thinking wrong here.[/QUOTE]
http://www.prismasonic.com/english/specs.shtml
Confirms this. However, it also confirms that the lenses have some geometric distortion and chromatic abberation. Too high a price to pay? It doesn's specify how you adjust the stretching - I assume manually?
Are there any "perfect" anamoprhic lenses without any abberations?
Mark
Vern Dias
06-27-05, 07:12 AM
IMHO, you guys need to drop the theory and just do it.
As far as HD, well I'll cross that bridge when I come to it. Right now, for all practical purposes, there is no actual full definition (1920 horizontal alternating white/black lines) HD on the market.
Broadcast resolves ~ 1440 pixels horizontally (on a good day) (and assuming you are not watching ABC or Fox, or ESPN), DirecTV is even worse, (when HBO doesn't crop 2.35 to 1.77), most HDTV cameras are either 1280x720 or even if they output in 1920 are actually interpolated up from a 1440 pixel wide imaging chip. WM HDV is almost never capable of resolving the full 1920 either.
Oh yeah, then there's the upcoming format war for HD on disc.
There are some amazing looking 2.40:1 DVD's out there today. Moulin Rouge, Phantom Of the Opera, SW IV, V, and VI are just a few that spring to mind.
They are not HDTV, whatever that is (remember 1280x 720 is HDTV and a 1920 pixel projector can render a scaled 1280 horizontal pixels at almost any resolution with little or no loss of horizontal resolution) but they are available today.
The reality is that when I run a WMV HD title scaled to 1.85:1 on my Qualia without removing the anamorphic lens, it looks as good or better than the same title played on my Sharp 12000 without an anamorphic lens.
Maybe 5 years from now, when (if) there is a decent selection of HD available and 4K home projectors are available for a reasonable price, I'll be reconfiguring my system.
As always, YMMV.
Just my $.02.
Vern
Dennis Erskine
06-27-05, 07:57 AM
Even with HD, movies are very often shown "letterbox"; ie, a 2.35:1 image in a 16:9 frame. The same process used to fill the screen with a DVD is used on an HD broadcast to restore the 2.35:1 to full panel resolution. Thus, 4K projector or not, a move broadcast in HD will not take advantage of full panel resolution without the 2.35:1 "system" in place.
[QUOTE=Vern Dias]IMHO, you guys need to drop the theory and just do it.[/quote]
Ignorance isn't bliss in my book ;)
As far as HD, well I'll cross that bridge when I come to it. Right now, for all practical purposes, there is no actual full definition (1920 horizontal alternating white/black lines) HD on the market.
Broadcast resolves ~ 1440 pixels horizontally (on a good day) (and assuming you are not watching ABC or Fox, or ESPN), DirecTV is even worse, (when HBO doesn't crop 2.35 to 1.77), most HDTV cameras are either 1280x720 or even if they output in 1920 are actually interpolated up from a 1440 pixel wide imaging chip. WM HDV is almost never capable of resolving the full 1920 either.
All of the above is correct, and the problem there is that when you are forced to squash and rescale the image prior to anamorphic stretch you are chucking away a greater proportion of the actual resolution than from a true hi-def source and risking the introduction of scaling artefacts, which when magnified by the anamorphic lens are going to be all the more obvious.
As I originally commented, my new cinema, for which I am considering a 2.35:1 constant-height setup is being developed now with the aim to get it ready for the release of HD-DVD/Blu Ray later this year. It's primary purpose will be to display high definition material, but yes, I will use DVD and other sources until I can replace them.
Therefore, I am taking my time to understand the issues and look for solutions. Is there any harm in that?
The way it stands right now, I believe that I will be happy to go ahead with the 2.35:1 constant-height setup, with it's limitations, as highlighted in the thread above, until such a time that I can install a 4k projector and remove those limitations.
Cheers,
Mark.
[QUOTE=Dennis Erskine]Even with HD, movies are very often shown "letterbox"; ie, a 2.35:1 image in a 16:9 frame. The same process used to fill the screen with a DVD is used on an HD broadcast to restore the 2.35:1 to full panel resolution. Thus, 4K projector or not, a move broadcast in HD will not take advantage of full panel resolution without the 2.35:1 "system" in place.[/QUOTE]
Right.
But what the 4k panel allows you to do, when using a fixed stretch anamorphic lens, which the 2k panel cannot, is scale any image greater than 1.78:1 in preparation for the anamorphic stretch without any loss of original resolution. With a 2k panel you would always lose some original horizontal resolution.
This is Michel's point. If you want a 2.35 constant-height setup which does not lose any original source resolution the panel must be twice the resolution of the source. The only other way to do it is to use a variable stretch anamorphic lens.
Mark.
Vern Dias
06-27-05, 09:46 AM
the panel must be twice the resolution of the source
Not true. In my first example, it must be at least the difference between the source AR and the target AR. However this first set of examples really don't address an anamorphic lens environment.
Example:
I have a 720P (1280 pixels horizontally) 1.77:1 source that displays at 128" wide. I am going to scale it to 174" wide (2.40:1).
I am displaying the 720P image at a resolution of 10 pixels per inch. In order to display that image at the same resolution on a 174" screen, my projector must have at least 1740 pixels of horizontal resolution. That means I only need an increase of resolution of 136%, not 200% to preserve the same on screen resolution.
Now take that same example and apply it to the current Real Maximum resolution of most HD today which is ~1440 pixels horizontally.
144" wide 1.77 source, 195" wide 2.40:1 image now I need 1950 pixels of horizontal resolution on the projector.
Believe me, your eyes are not going to see the 30 pixel diffference.
And that's a worst case scenario..... and not the scenario that arises when using an anamorphic lens....
Read On...
I believe that part of the confusion is coming from the fact that the anamorphic lens alters the scaling requirements because it alters the relative horizontal size of the pixels, so:
Let's look at it from the other direction:
Let's assume a hypothetical 1920 alternating white/black line resolution 2.40:1 source with a 1.33x anamorphic lens being projected on a 192" wide screen.
Again we have 10 lines per inch on the screen.
If we choose to project a 1.77:1 image (worst case), we only need 142" of screen or 1420 horizontal pixels to maintain the same visible 10 lines per inch resolution of the 2.40:1 source. Yes, we have discarded some of the sources native resolution IF the source's true horizontal resolution (not pixel count) is > 1420. My contention is that it almost never is. Is it obviously visible? Not to me.
Since the distance from the viewer to the screen (which is a basic tennant of constant height projection) hasn't changed, the perceived resolution hasn't changed either. So, actiually we need less resolution, not more to handle the projection of any AR below 2.40:1.
Also, no scaling is being done on the panel or in the projector. It is being done in the scaler or the HTPC and presented to the projector in the proper AR to be corrected by the anamorphic lens to the proper screen AR. In the case of the HTPC, in my system it is actually being done in two steps for DVD, a software upscale of 2X and then the final scaling to the correct AR (with the anamorphic lens factored in) is being done by the video hardware/software (VMR9). HD sources omit the inital upscale.
Using an NVidia 7800GTX video card with its advanced scaling capabilities also has an impact on the final image quality.
Would a 4K projector help this situation? Not that I can see, until we have 4K resolution source material.
What we do lose in this scanario is exactly what was said in an earlier post by Dennis Erskine. We lose vertical resolution in increasing amounts as the AR increases.
However, when you consider the ratio of resolution (1080 x 1920 or 1.77) conpared the AR of the screen (2.40) we can afford to burn some vertical resolution and still view a very good image.
Vern
[QUOTE=Vern Dias]Not true. In my first example, it must be at least the difference between the source AR and the target AR. However this first set of examples really don't address an anamorphic lens environment.
Example:
I have a 720P (1280 pixels horizontally) 1.77:1 source that displays at 128" wide. I am going to scale it to 174" wide (2.40:1).
I am displaying the 720P image at a resolution of 10 pixels per inch. In order to display that image at the same resolution on a 174" screen, my projector must have at least 1740 pixels of horizontal resolution. That means I only need an increase of resolution of 136%, not 200% to preserve the same on screen resolution.
[/quote]
Vern, sounds like we're getting into some theory here ;)
Show me a 1740 horizontal pixel panel please :p My comment, re twice the size was simply based around the fact that the next size panel up from 2k is 4k.
Mark
Vern Dias
06-27-05, 10:09 AM
Show me a 1740 horizontal pixel panel please
As long as it's less than 1920, a 4K panel isn't needed.
Vern
[QUOTE=Vern Dias]Also, no scaling is being done on the panel or in the projector. It is being done in the scaler or the HTPC and presented to the projector in the proper AR to be corrected by the anamorphic lens to the proper screen AR. In the case of the HTPC, in my system it is actually being done in two steps for DVD, a software upscale of 2X and then the final scaling to the correct AR (with the anamorphic lens factored in) is being done by the video hardware/software (VMR9). HD sources omit the inital upscale.
[/QUOTE]
Vern, however you juggle it, your projector has a finite horizontal resolution. If you start with a source with the same horizontal resolution, in order to use the anamorphic lens for aspect ratios between 1.78:1 and your screen's native aspect ratio you will have to interpolate some of that resolution away to give the lens something to stretch back to the correct aspect ratio.
How far do you sit from the screen? Perhaps that is the key - sitting so far back you cannot see? ;)
Mark.
Vern Dias
06-28-05, 04:44 AM
I sit 14' back from a 13' wide screen. And I have 20/20 (corrected) vision. So I still think that this issue is the proverbial mountain being made out of molehill. ;)
All AR's numerically lower than the AR of the screen must be scaled (interpolated), not just those below 1.77. This obviously includes 1.66:1 and 1.33:1. The key lies in how ell you do this. A two step scaling process with an HTPC using ffdshow with a Lanczos 2 scaling algorithm for the first and a state 0f the art video card equipped with nVidias pure video for the second can do an amazingly good job of it.
When was the last time you watched a DVD and clearly saw the peach fuzz on a girls face or individual strands of hair blow around in the wind? All very common occurrences on my system, regardless of the AR of the source.
Apparently, nothing I say will convince you otherwise, so this will be my last post on this subject.
I will continue to enjoy my "excessively compromised" image, because it is the best image that can be produced with today's commonly available technology, secure in knowing it is far more immersive and engaging than any possible alternatives for my HT.
BTW, the image stands up extremely well when compared to my 35mm setup.
Vern
[QUOTE=Vern Dias]I sit 14' back from a 13' wide screen. And I have 20/20 (corrected) vision. So I still think that this issue is the proverbial mountain being made out of molehill. ;)
[/quote]
Very likely. I can only accept your experience on this matter as I have yet to see this set up in action. And I *do* appreciate your comments.
All AR's numerically lower than the AR of the screen must be scaled (interpolated), not just those below 1.77. This obviously includes 1.66:1 and 1.33:1.
Unless you use a passthrough or remove the anamorphic lens, right?
The key lies in how ell you do this. A two step scaling process with an HTPC using ffdshow with a Lanczos 2 scaling algorithm for the first and a state 0f the art video card equipped with nVidias pure video for the second can do an amazingly good job of it.
Again I haven't seen this particular setup. I can only base my expectations on my understanding of how scalers work.
When was the last time you watched a DVD and clearly saw the peach fuzz on a girls face or individual strands of hair blow around in the wind? All very common occurrences on my system, regardless of the AR of the source.
You shouldn't make judgements on the quality of my system ;) But for reference, I use a Barco Reality 12" CRT with a Meridian 800 DVD player feeding a Faroudja 5000 scaler via component and a Lumagen Pro HD via SDI. I project onto a 10' StewartTek screen and sit about 12' back. I can see every pixel on a DVD and very clearly any and all artefacts.
Apparently, nothing I say will convince you otherwise, so this will be my last post on this subject.
Vern, please don't take anything I say as personal. I'm simply, and correctly, pointing out that scaling in a 2.35:1 setup up is unnavoidable. And scaling risks introducing nasty artefacts. Downscaling more so than upscaling (hence why a 4k panel would be desirable with HD sources). DVD quality is already poor enough and I am concerned about the potential to degrade it further.
I will continue to enjoy my "excessively compromised" image, because it is the best image that can be produced with today's commonly available technology, secure in knowing it is far more immersive and engaging than any possible alternatives for my HT.
I will certainly join you later this year with my own compromised solution ;)
BTW, the image stands up extremely well when compared to my 35mm setup.
That's very encouraging to know.
Mark
Blah, Blah, Blah, Blah, Blah..
Whats thats you ask?
Now you know how I feel after reading the last few posts :D
Seriously though both of you two seem very knowledgeable in the topic. More than I ever would. Lets just accept DVD's can look pretty darn good with current equipment as can HDTV. You could go into all the technicalities to prove each other wrong but what for.
Lets all just enjoy the show! :)
Peace Out
[QUOTE=Tukkis]Blah, Blah, Blah, Blah, Blah..
Whats thats you ask?
Now you know how I feel after reading the last few posts :D
[/quote]
Hehe apologies :D
Seriously though both of you two seem very knowledgeable in the topic. More than I ever would. Lets just accept DVD's can look pretty darn good with current equipment as can HDTV. You could go into all the technicalities to prove each other wrong but what for.
Well, ultimately I believe we'd both agree and prove each other right - the truth is the truth after all ;) Everybody benefits from an open and reasonable discussion. Highlighting potential weaknesses in any setup enables everybody to look for solutions which ultimately lead to even higher image quality and even more enjoyment. That is one reason why this forum is so cool.
Lets all just enjoy the show! :)
Always do :D
Mark
Dan Biland
06-30-05, 05:25 PM
[QUOTE=Mark_H]Alan, yes I have a Barco 812 hanging from my ceiling.
I am now building my next cinema and will be retiring the 812 for something more sigh digital :D
Mark[/QUOTE]
Mark H., Do you happen to know what the Barco 812 is worth, seeing you own one? Also how hard is it to calibrate the tubes and how often does it need to be done?
Worth today? I have no idea. It cost around £70k new.
As for calibration - it's no more difficult than many CRTs, though there were some annoyances we initially had to work through with Barco. My current convergence setup has been stable for well over a year now - not the slightest bit of drift.
Mark.
Mark:
Very interesting, could you describe in detail what you plan to include in your new digital cinema?
Lon
bills2k
07-20-05, 08:11 PM
Mark:
The Ashes begin tomorrow. I can't wait.
Mark:
The Ashes begin tomorrow. I can't wait.
Warney, Warney!
Ooh ahh Glenn McGrath , I said ooh ahh Glenn McGrath !
bills2k
07-20-05, 10:40 PM
Glenn and Brett will create havoc. What's Vaughan got to do with it?
What's Vaughan got to do with it?
Nothing. I was talking about Shane Warne :)
[QUOTE=LJG]Mark:
Very interesting, could you describe in detail what you plan to include in your new digital cinema?
Lon[/QUOTE]
Hey Lon,
Nothing is decided yet. First I need to get the new room designed and built. My architect is working on this. We are also talking to various acoustic specialists to get the internal space right. All this is going to take a few months to complete, by which time I hope there is a clearer choice for projectors and support electronics.
Cheers,
Mark
Quickly back to CIH...
The anamorphic lens (in most cases) are fixed stretch, correct? If that is the case, why would you apply different amounts of squeeze via a scaler for different ARs?
Mark
bills2k
10-17-05, 08:44 AM
Mark:
You are absolutely right. The anamorphic lens sets up a fixed stretch. For example, if you go to the thread in this forum where Alan has posted pictures from different set ups by forum members you will see that yourself. My photos are from Six Feet Under from HBO. It looks great. The only thing is that since it is not in the correct AR the picture is cropped. Personally, I do not mind watching everything in the CIH mode. Others like to watch in the original ARs thereby having bars on the side which can be properly masked. I love recreating that cinematic experience at home.
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