Axiom Home Page Forums General Discussion Home Theater Screen size -- how big is too big ?

I'm probably just starting to discover what the movie industry has known for years, but here goes...

My screen right now is a 4x8 piece of matte white Formica, which is working surprisingly well. This allows roughly 104" diagonal on 2.35:1 movies (96x41) and 97" diagonal on 16:9 movies (85x48). Viewing distance is about 12 feet, just far enough that I don't see any screen door effect unless move closer.

When I watch films with fast action at 16:9 I seem to "lose the picture", ie I feel like there is too much happening for me to keep an eye on everything. Oddly enough, when watching a 2.35:1 movie with slightly higher magnification and larger diagonal (104" vs. 97") I have no such problem.

I used to think that going with a 2.35:1 screen would mean I would lose the ability to have a "nice sized" image when watching 16:9 movies, but it is now starting to appear that the larger 16:9 image may be too big for my eyes and brain anyways.

Has anyone else noticed this effect ? I did a casual search on the net for information but it was kinda late so it wasn't a very intensive search.

This is, regrettably, another small step towards a 2.35:1 CH arrangement. Help, I'm slipping down the slope...

I read somewhere that 3 times diagonal is the optimal viewing distance. Maybe you are too close?

Edit: 3x for SD, 2X for HD, minimums. 5X maximum. Based on 20/20 vision.

Maybe I'm too far away!

You have normal human eyes, if you ask me. You are noticing on the 16:9 that there is more vertical image than your eyes are used to "processing". Human eyes tend to focus on a single vertical point, but are used to having left and right peripheral vision. That is why a wider image seems less straining than a taller image.

I have a 104" 16:9 screen that I was watching from 12 feet, and I was OK with it, but mostly because my movies are in a wider format than that. Now that I am in my new room with about a 14' viewing distance, 16:9 material seems better on the eyes.

If I was doing it all over again, I would go with a wider format screen and lose a little 16:9 image size.

For my setup 2.35 movies take up my entire screen which is 51" x 120" (2.35 AR). In the front row fast action movies can sometimes be overwhelming. Similar to sitting in the front row at theaters or lower rows at IMAX, it sucks.

Anyway, I have found my second row of seating more comfortable for those types of movies, which is about 15ft or so back. Chick Flicks are usually ok from the front row on 2.35 movies.

For 1.85 AR DVD's I change the lens to "pass through" mode which displays the native image and uses 51" x 94" of my screen. Either row works for that scenario...

John:
Did you ever consider a 27" CRT? Oh, wait... never mind....

LOL! Boy! You're getting off some good ones lately, Mark (see "hookahs" and "hoes" )

Thanks, everyone. Guess I'm going to get out the knife and trim this to 41x96 for a 2.35 screen. I was hoping to avoid all that zooming and panning when I went from 16:9 to 2.35:1, but I'm finding I need to adjust anyways because I like having the 2.35 movies at the top of the 4x8 panel rather than in the middle of the 16:9 projector pattern.

BTW I saw a neat border treatment on avsforums a couple of days ago -- I originally planned to have a pine border to match the rest of the trim in the house but black borders do so much more for the image quality. This guy had a 6" black border around the screen, with a 2-3" border on top of that. The result was a ~3" black border but the screen still looked like it really fit the room.

Who am I kidding ? I'm probably going to put a strip of black hockey tape around the screen

EDIT: interesting link : http://home1.gte.net/res18h39/thxscope.gif

Looks like my 12' viewing distance is pretty much optimal for a 96" wide 2.35 screen.

Also noticed that a couple of folks referred to this as 2.39 rather than 2.35. Turns out that around 1970 the standard went from 2.35 to 2.39, ie Randy's screen is an inch too high for modern movies but that can be fixed with a black marker

Also, the optimal distance for Randy's 120" wide screen seems to be 15.4 feet, so the second row should be ideal.

I wonder whether the anamorphic lenses stretch 16:9 to 2.35 or 2.39 ?

Hmmm. That diagram shows that I should have about a 120" diagonal 2.35:1 screen... Of course that means that I would have to chuck my $660 Carada 16:9 Brilliant White screen and get a new $744 Carada 2.35:1 High Contrast Grey screen. Oh, and then a $1200 anamorphic lens to really get some good use out of my projector... I don't think that I have the extra $2000 to change it out now...

Oh, for the Prismasonic H600M Anamorphic Lens that Randy has, the web site claims that it will take a 16:9 and go to a 21:9 (2.333333:1) so that would be a neither of your numbers (2.35:1 or 2.39:1)

I have many movies that have wider AR's than 2.35 John. Yes, at least the Prismasonic allows me to stretch to work with those as well. The units have "stops" which are basically little allen head screws that you can adjust for "pass through" and "stretch" modes so when you turn the knobs, they stop where you want them. So basically I have them set for the widest movie I have, and then just don't turn the knobs as far for 2.35 material.

Huh ? Are you saying you can do a "variable stretch" ? I had no idea... thought all you could do was have the lens "in" or "out".

This is sounding better all the time !!

There are Horizontal and Vertical Stretch lens designs. Mine is a Horizontal design, so first my theatetek software vertically stretches the 2.35 image to get rid of the black bars, then I turn my knobs on the lens which horizontally reformats the image to fill the 2.35 screen. The nice thing about a Horizontal design is that you can get a pretty big image from a relatively shorter throw distance.

A vertical lens actualy squeezes the image down to form the same 2.35 image but the end result is a smaller size from the same throw distance. Most people with vertical lens have longer throw projectors.

I’m still trying to figure all this out myself, so I really don’t know squat. One thing that I continue to see referenced at AVS with these lenses is throw distance. Apparently, some lenses don’t do so hot with short throws under about 15 feet. You might want to do a little digging on the lens capabilities a bit before you commit yourself into incorporating one into your set up. The lenses recommended for short throws are pretty expensive I think. (above 3500 US).

When you get all this figured out John, let me know what you come up with eh? That way I can just copy what you do. My set up is about the same as yours (seating and throw distances).

Oh, you might as well start looking into video processors too. That seams to be the norm with folks who use anamorphic lenses.

You want to take your throw distance/width (width of original unstretched image) = ratio of compatiblity.



For the most part anything over 1.3 should work with small pincussion effect. In my case with a 13ft throw on my Z2 and 7.57ft width (16:9) gave me around a 1.7 ratio. Another important factor is that you want to place your projector so your using as little of zoom as possible to get your desired screensize. The less zoom you use the less artifacts.



Obviously a longer throw distance would end with a higher ratio, and potentially less distortion, but I can tell you my picture looks very nice and I have very little pincussion at 13ft with my short throw Z2.

Ahh... the width of the UNSTRETCHED image. That makes a big difference... and makes more sense now that I think about it. I'm probably going to end up with the projector 14 feet away and a 6 foot unstretched width, so should be solidly in the green.

My new Z4 projector has a "zoom" setting which, at first glance, seems to automatically expand a 2.35 movie to full height. Running it with a 480p input right now -- I know some projectors won't zoom a 720p input the same way they do with 480, and others won't zoom an HDMI input, but I'll see how far I can go without a video processor or HTPC.

Yes, Randy, I can see from my own typing that some time in the last couple of hours I gave in. Not gonna buy any more toys until I sell the old house though.

When I had my Z2 mated with the Panasonic S97S upconverting DVD player, I could use the Zoom button to cycle through the options. One of them would take the 480 image of the 2.35 movie and vertically stretch it to get rid of the black bars. The width was not changed so everything in the movie looked skinny. Then you would use the lens to make it look normal again. However, with the Z2 and S97S, I was unable to use this zoom option over DVD/HDMI, the signal was locked.

It is my understanding that the Z4 WILL stretch(scale) an incoming HDMI signal from either a upconverting DVD player or a HTPC that is running DVD software that does not have a built in stretch option like Theatertek.

I know at one point someone pointed me to the part in the manual where it talked about the additional ZOOM options on the Z4, that the Z3 or Z2 did not have.

The HTPC route would most likely cost more to build, but personally I think the scaling ability is much better as you can set your resolution to natively match that of the projector 1280 x 720. My HTPC has a Nvidia 6600GT which does a great job.

You may find it easier just to buy an OPPO or some other good upconverting DVD player. I'm not sure what will happen with these new HD DVD players in regards to 2.35 movies.

This stuff makes my head hurt.

Alright, I am starting to get confused here. I am planning on having a 16:9 screen, you guys are saying you are going to have a 2.35 screen? So what do you do when you have a full 16:9 image?

-Robb.

set the lens to "pass-through" and mask the sides of the 2.35 screen (using curtains etc...), like they do at the movies.

I have a 16:9 format screen and every time I watch a movie, I wish I had something to mask off the top and the bottom of the screen, but I haven't come up with a low cost, yet nice looking, way to do it. If I had a 2.35:1 screen, then the issue would be bars on the right and left side instead of the top and bottom like on my 16:9 screen. Those would be easier to just hang some sort of mask on each side (thanks to gravity) and adjust them as needed. SkyHawk is right on the mark. That is what movie theaters do.

For my 16:9 screen, I will have to find something rigid, yet light, to put over the top and bottom bars. Not that easy over a 8' span.

Randy,

AVS is having a power buy on the new panimorph lens. http://www.panamorph.com/UH350Program.html

I was tempted to buy one, but am leery if it will work in my situation very well. (12' seating distance and an 11.5' throw). What do you think???

In a 2.35 constant height setup, all Aspect Ratios keep the same height, the only thing that changes is the width, which is much easier to mask if you desire. At this point in time for 16:9 or 1.85 DVD's the side bars don't even bother me.

Another benefit of this setup using an anamorphic lens, is that you reclaim the 33% lost by the black bars, which in turns gives you upto 20%+ more brightness. When you watch 2.35 movies on a 16:9 screen, your giving up 33% of the pixels to the bars.

>>Alright, I am starting to get confused here. I am planning on having a 16:9 screen, you guys are saying you are going to have a 2.35 screen? So what do you do when you have a full 16:9 image?

If you don't have one of these fancy lenses (and most people don't), the best thing is probably to stay with a 16:9 screen and live with the black bars top and bottom when watching a 2.35 movie.

If you have one of these lenses and the right "stretching" capabilities in your system (projector, HTPC, player) then you can get a 2.35 screen and flip back and forth between 16:9 and 2.35:1 pretty easily. It's a question of whether you are optimizing for 16:9/1.85:1 or for 2.35:1.

(EDIT - the following paragraph actually answers your question, the rest is just "background" )

You can also run with a 2.35 screen without the lens/prism if you don't mind fiddling with the zoom and lens shift every time you go between 2.35 and 1.85 content, since with a 2.35 screen you need to zoom out in order to fit the taller 16:9/1.85:1 image on the 2.35 screen. Usually you have to shift the image as well, so it is a pain in the butt.

The decision making process, I think, is :

1. Am I going to end up with a lens/prism eventually ?

2. Can I live with the zoom/shift hassles in the meantime ?

If the answers to both questions are "yes", then get a 2.35 screen. If the answer to either question is "no", then get a 16:9 screen.

One day projectors and DVDs will have 2.35:1 native support (I hear a couple of projectors do already) and this will be easier, but for now a 2.35 system is kind-of on the bleeding edge.

But it gets worse. Do you want to hear about "blended" systems, where you use a custom video processor and 2 cheap 4:3 projectors running side by side to get a 2.35:1 image ?

Such a neat hobby

Keep in mind that if you use the zoom methods, your still not reclaiming the full panel of the projector for the image. So the zoomed "to fit the screen" option will not be as good of an image as if you were able to scale the image and reclaim those lost pixels.

Absolutely. It just lets you have a nice wide screen.

In my case going with 2.35 lets me have a larger screen, since I have to fit into a loft with 45 degree walls

A good rule of thumb is 1.3-1.5 times back the screen width.

The miracle of the Internet:

Just a few days ago, I was a confused shmuck with a 4x8 sheet of Formica velcro'ed to my wall, unsure whether to cut it to 2.35:1 or 16:9 aspect ratio. I didn't want to cut to 16:9 because I really liked the 2.35 movies to be a bit wider -- cutting to 2.35 seemed better but when I simulated a 2.35 screen it made the 16:9 and 1.85 movies just a bit too small. Even buying one of those fancy-schmancy lenses didn't seem to solve all of my problems, although I have to admit Randy's Prismasonic still seems like it comes closest without spending insane money.

But no more !!!

After only a couple of days of research, without making any changes to my system, I am now the proud owner of a "constant-area" system, the coolest thing in the home theater world.

I owe Randy quite a lot of beer for suggesting an aspect ratio midway between 16:9 and 2.35 -- turns out I'm not the only one who is not completely satisfied with either of those two aspect ratios.

Room size seems to be the key -- if you have enough space for a big honkin' 2.35 screen (like Randy's) then everything is happy, but the biggest I can run is about 8 feet wide and that makes the 16:9 content seem just the tiniest bit too small. In that case, having a screen around 2.06:1 is ideal -- you use the full width for 2.35:1, and use the full height for 16:9, 1.85:1, or 4:3.

So... now I can relax and go back to watching movies. I will still have to zoom and shift when going from one format to another, and I'll have to play with some moveable borders for the 4x8 screen, but now I have a plan. Probably will still want to add a lens at some point, but I can live without it for a while.

Thanks for all the great input and suggestions. I'm going to go off and do some zooming and shifting

Quote:

---

John, I would love to have a beer with you sometime, just have to figure out how we would accomplish this task.

---

John could paypal you the amount for the beer. then you guys could start a new thread in the watercooler titled: Randy and John share a beer! then you guys could post back and forth while enjoying your beers together. lol

I don't believe it. Some idiot bought a FULLSCREEN copy of "Attack of the Clones". Never noticed it before because I was watching on a 4:3 TV. If I ever find out who is responsible for buying the DVDs around here... oh wait...

The image looks very... tall.

I discovered something else in the process... might be unique to my projector, but I have a sinking feeling it is common to all widescreen displays. When I play a 4:3 DVD, unless I fiddle with the projector settings the image is stretched across to the full 16:9 panel area. If I flip the projector's "Screen" setting from "Full" to "Normal" I get a 4:3 image with bars on the sides. Manual says Full = 16:9, Normal = 4:3.

Why do I care ? Because my "no scaler, no HTPC" approach to 2.35 CH was going to be picking up a used Panamorph vertical compression lens, mounting the projector back 20 feet as originally designed, leaving the lens in place all the time, and using the "Normal" setting on the projector to squish 16:9 content down so it would appear normal after going through the lens.

That should work fine for 16:9 content, but it means I have no solution for playing 4:3 content without moving the lens or finding a "double-squish" setting on the projector.

Is setting the lens to "pass through" just pushing a switch or lever to do this or is it more complicated than that. I am also confused about this point.

Just saw an artice for a Funco CineWide a couple weeks ago. It uses electronic processing to stretch the image vertically and an auxiliary anamorphic lens to stretch it horizontally. It claims that by doing this, all pixels were used to make the 2.35 image. But since this is a Runco I bet they start at about $10k. We can only hope that more companies will catch on an we could get an affordable version of this in the near future. I would also like to watch movies on a 2.35 screen when I get a projector in a few years since I mostly watch movies.

Correction: Runco not Funco

the "f" and "r" are right next to each other

On the Prismasonic lens, you have two knobs. So when you have a 2.35 movie, you just turn the knobs to stretch the right/left sides of the image horizontaly to fill the 2.35 screen. When watching a 1.85 DVD or 16:9 HD channel, you turn them back to "pass through" mode, so the image is just as if you didn't have a lens in place.

Hey Randy, your last comment made me wonder...

Does use of a 2.35:1 lens like yours reduce the brightness of the projector? I mean, I wouldn't expect it to be noticable or anything, but when you use a 2x teleconverter on a camera, the effective f-stop changes. Maybe it's a different principle.

What Randy just described seems to be one of the big attractions of the Prismasonic products. With a Panamorph lens, either vertical compression or the new horizontal expansion, you have to physically remove the lens, either with one of Panamorph's very high quality motorized transports (which cost about the same as the lens) or with a DIY-equivalent made from a couple of drawer slides and a scrap of plywood. Fortunately the alignment between lens and projector does not seem to affect image quality, although a real cheap DIY transport probably results in some image shift.

For anyone not completely sick of my own HT adventures, I have "plan B" up and running. Turns out that if you have the projector at the right height, you can get the right amount of vertical image shift "for free" when you zoom between the right settings for 2.35:1 and 16:9.

In my case I wanted the 2.35 image to be aligned at the top of the screen so that eye level would remain 1/3 of the way up from the bottom of the image. That meant the projector lens needed to be about an inch above the bottom of the 4x8 screen, or raised about 4" from its current location on the top of a picnic cooler (don't ask).

The results are great. I have to manually zoom when switching aspect ratios but no shifting required, ie other than keeping greasy fingers away from the lens the aspect ratio change can be handled by anyone. When visitors bring kids who might be watching unattended the plan is to leave the screen masks at 16:9 and live with a slightly smaller 2.35 image. This what the HT geeks call "constant width operation" and the rest of us call "stop mucking with the projector and watch the movie".

All I need now is to add some masks to the screen. I need about 7" of fixed masking above the top of the screen to handle the black bars which splash over the top when zoomed in for a 2.35 movie, a moveable 7" mask at the bottom of the screen, and 2 moveable 6" masks at the sides. I'm thinking about trying to rig a bit of a shadow box around the screen as well, which would also provide a "parking spot" and protection for the unused masks.

Here's a link to a guy who did a nice setup with fabric masks, only his system aligns the images at the bottom of the screen rather than the top. I think this was necessary because his screen is mounted higher than mine :

http://dustin.bunnyhug.net/

One note I should make re: previous posts. Earlier I said that a constant-area rig was a good alternative to a "big honkin' 2.35 screen". After some thought I have refined this -- constant area is a good alternative to a "big 2.35 screen" or a "big honkin' 16:9 screen". Jakeman runs a really big 16:9 screen in his HT and the 2.35 movies look fantastic... but then his screen is almost 10 feet wide.

>>Does use of a 2.35:1 lens like yours reduce the brightness of the projector? I mean, I wouldn't expect it to be noticable or anything, but when you use a 2x teleconverter on a camera, the effective f-stop changes. Maybe it's a different principle.

Good question. It took me a while to get my head around it... in fact after a couple of attempts I am on the verge of giving up and waiting for Randy to answer.

The short answer is "if you zoom out so the 2.35 image ends up the same width it was before you added horizontal stretch from the lens and vertical stretch from the projector/player, then the image is actually BRIGHTER than before because you are using all of the LCD panel rather than just the middle 3/4.

I imagine that if you just stick the lens in front and make the image wider then it will be less bright, exactly as you would expect.

The trick is that you do a number of other things at the same time, none of which can be done without the lens, and the result of all those actions together is a sharper, brighter 2.35 image.

EDIT -- you can tell this isn't simple -- I had to edit my own post three times before it was what I considered "readable". Hint -- if you think about a vertical compression lens rather than a horizontal expansion lens it's a bit easier to grasp, even if the trend seems to be towards horizontal expansion lenses these days.

FWIW, I think the big advantage of vertical compression lenses is that if the projector is already mounted you don't need to move it or change the zoom settings. Many projectors still don't have the 1.33 zoom range you need to compensate for the horizontal expansion, and even the ones that do are rarely mounted in a position where you have enough unused zoom range.

I do not see any reduction in the brightness of the image for any material. Actualy for 2.35 movies, the image can be upto 20% brighter. Because you are reclaiming 33% of the pixels that were taken up by the black bars, your image actualy improves and can be brighter.

I'm kind of fascinated by all of this.

John, the answer to your original inquiry is "size doesn't matter".

Also, tell me about the picnic cooler...

You know, nobody has ever said it to ME.

Hi Gang,

I had the pleasure of seeing the Runco Cinewide in action at my local HIFI store. Let me tell you, it was freakin' awesome! The lens moves while the projector stretches the image. It looks like you are in the movie.....best rig I have ever seen. The entire 2:35 image is displayed without looking distorted at all. Simply amazing....

Of course all this grandure comes with a hefty price. The projector was $38K and the lens was $10K. If you go with Runco you are getting the best there is....so skip the new house or car if you want these bad boys. If I had the money to afford it I would do it in a heart beat.

One word of caution....if you do venture out to see this technology, you will be forever scarred knowing whatever you buy will not look nearly as good...

Huh. I totally read that as Runco Cowhide.

>>You lost me but I am late to the game anyway. Unless you are running CH on your formica, then the 16:9 image should be longer diagonally than a 2.35.

That's what I expected as well, but if you pull out the calculator the 2.35 actually ends up with a bigger diagonal. The 2.35 image is limited by the width at 41x96 or ~104" diagonal, while the 16:9 image is limited by the height to 48 x 85 or about 97" diagonal.

Note that the area of the two screens is actually a better measurement than the diagonal. The 2.35:1 screen area is 3936 in^2 while the 16:9 screen area is 4176 in^2, so the 16:9 image is larger even though the diagonal is smaller.

>>I have a graywolf 106" that is almost exactly 8 feet wide. In 2.35 mode, non constant height, I am probably down to the 97 or so you have listed for 16:9. Does that sound right?

It depends on how high your screen is. If it's a 16:9 106" screen then the height will be more like 54" high (4-1/2 feet) so you will get an honest 106" diagonal.

You have a nice big screen there -- bigger than mine -- so you have more flexibility. If I were buying a real screen (rather than coasting with the Formica until I figured out what I should get) then something like your screen would be at the top of my list.

So how’s your constant area project going?

I’m now felling your pain. I mounted my Panny 900 yesterday and watched some different DVD’s on my fancy shmancy flannel off-white bed sheet. No sound yet and I wish I would have ironed the sheet first. After a couple hours of watching wrinkled movies with the gentle hum of the projector above me for sound, I am about to give up on the hole constant height thing I was planning on doing. When I plop my ass down to watch a movie I just want to hit a button or two on the remote. I don’t want to be screwing around with manual zooming, lens shifting or masking or messing with lenses. I’m now thinking that I’m just going to go with a 16.9 screen and live with the black bars on the top and bottom. They’re not all that noticeable to me anyway. My pending delema is that I’m sitting 12’ away from the bed sheet and I just can’t seam to find the ‘happy’ screen size for all the different movie A/R's.

One thing’s for certain though, I’m really digging the ‘big picture’ experience. I can’t wait to get some sound. I figure the bed sheet will be on the wall for a few weeks until I can figure out what screen size I like. I might even take it down and iron it.

What's behind the sheet? I was surprised before I got my screen that my theater's red walls were watchable. Not as good as the screen, but not that bad. It may be better for you than the wrinkled/wavy sheet?

I also have the 16:9 screen. I am width constrained and so it works best for me. When watching 2.4:1 movies, if you have a dark room (black ceiling, dark colored walls), and good light control- the bars on top and bottom dissapear to me. I don't notice them at all unless I look at them. It helps to have a decent black level out of the projector too.

Enjoy the setup! You'll love it when complete (with a fixed screen and Axiom sound).

Dave.

>>I don’t want to be screwing around with manual zooming, lens shifting or masking or messing with lenses.

I have it pretty simple now -- just a zoom, no shifting. I guess I will have to add some masks at some point. It's a toss-up between buying an automated masking system and hiring someone to zoom the projector and move the masks so I don't have to get out of the chair. So far hiring someone looks to be much cheaper but I can't really afford either right now

>>My pending delema is that I’m sitting 12’ away from the bed sheet and I just can’t seam to find the ‘happy’ screen size for all the different movie A/R's.

I hate to say it, but this is exactly the reason why one would consider constant area in the first place.

I'm living quite happily with the CA setup right now, with the projector mounted on a table between two big chairs, but access to the viewing area is limited by the angled walls and I am starting to think I need an open walkway there so people can get in and out.

If I put a walkway there the projector will need to be mounted higher up -- if I align it with the top of the screen (the other sweet spot for constant area) then I will bang my head every time I walk underneath, and if I mount it on the big vertical timber at the back of the loft (pre-wired with power and HDMI) then the projector is too far away for anything but a vertical compression CH setup.

I'm starting to understand why Ian & Amie have their projector mounted on a hinged plank that sticks out ~5 feet from the back wall, supported by a rope & cleats, looking for all the world like it escaped from a sailboat.

For me it is pretty painless also. The TheaterTek software has automatic aspect ratio adjustment, so all I have to do is turn a knob on my anamorphic lens during 2.35 movies. No biggy, I'm usually up/down anyway getting popcorn or kicking the kids out of the room when were watching "R" movies.

If I had room for a wider 2.35 screen I think I would be going the constant-height route since it is always going to be easier to live with than constant-area.

The fact that I am limited to about 8 feet of total screen width makes CA an attractive choice -- 16:9 movies on an 8' wide 2.35 screen seem just the tiniest bit too small.

I think I will measure again when I get home

I thought about building a HTPC, but the thought of fighting with yet one more stinking computer killed the idea. Between my home PC, my work PC, my personal laptop and my work laptop, I just don’t think I can deal with one more. Computers are great until they decide to misbehave, then I’m totally hosed because I don’t have the patience to screw with them.

The CIH thing is way cool, but way expensive too. $1500 and up for a lens, anther $2000 and up for a VP or buy a different projector that will stretch the image, then the masking system. My hour and a half or so look in awe at my wrinkled bed sheet should tie me over for a while. The image that 900 has over my 46” hd1080 mits TV is unbelievable. I can’t wait to see it on a real screen, and with sound.

I find that about 84 X 36" is the right size for the 2.35 stuff and 72 X 40 is about right for 16.9. But if I keep the height the same at 40", the 2.35 image is too big for me. I never would have guessed that picking the screen size would be this difficult.

Dave,

The whole room is a very dark garnet red in an eggshell finish. The front wall is solid and the rest of the room is what I call “Mike’s Mistake”. I tried to do some faux coloring with garbage bags and screwed it up royally. Ended up painting over it a couple times with the red to end up with something quite unusual. The image on the red wall didn’t show up at all. The black bars are non-existent. I could very easily zoom the 2.35 stuff if I make the screen wider and not even notice them, which is easy enough but I don’t want to have to shift the lens and zoom each time. So it’s either zoom and shift or zoom half way and mask the bottom.

Apparently the TheaterTek software can shift the 2.35 image up and down within the larger 16:9 frame, so you should be able to get rid of the need to shift that way.

I find computers work pretty well if you don't mess with them. I'm hoping that extends to my hypothetical HTPC

I read an article in Digital Tv and sound a few months ago. It said to find the optimal viewing distance for a 16:9 image is 3400*(image height in inches)/(vertical resolution). For example if you have a 50 TV with 1280 by 768 resolution then the vertical height is 24.5 inches. So the viewing distance would be 3400*24.5/768 = 108.8 inches. If the Tv were 1080p the viewing distance would be about 77 inches. If the TV were 480p the viewing distance would be 173 inches. Apparently this is the distance to sit to take advantage of the higher resolution. So if you sit 77 inches away from that 1080p display it wouldn't look any better than if it were 768p.

So here is where things get interesting. Within the next few years I imagine many people will have dvd's which are in 480p and high def dvd's in either 720p or 1080p. So what viewing distance do you set up? Do you set up a front row at the right distance for 1080p and the back row for 720p? Or just have one row and simply zoom in and out. I imagine once you go 1080p you won't want anything less.

- Nick

For my setup (16:9 image is 48" high, projector is 720p native) that means a 226" viewing distance, or about 19 feet. Was this an article in "Binocular Life" or something ?

For dealing with varying resolutions, my strategy is to adjust the system and seating positions for the highest resolution images then complain loudly when watching lower quality material. It seems to handle the wide range of DVD recording quality; I assume it would also work for regular DVD vs. HD-DVD/BluRay

Here you go, Jack. Settles everything, right?

Thanks !

I think the article is telling me that there are two different factors affecting seating distance -- one being the optimum viewing angle for best visual impact, and the other being getting as much detail as possible.

The clear message is that at any HT resolution available today, sitting at the optimum viewing distance for best visual impact (eg. the 36 degree THX recommendation) means that we could benefit from quite a bit more resolution -- or, alternatively, that we could sit much further back than we normally do without losing our ability to see all the detail in a current HT picture.

Going with the 36 degree THX recommendation means that (a) sitting at 11-12 feet is about right for my 7-8 foot wide image, and (b) we can upgrade a few more times before our eyes become the hard limit for how much more detail we can see.

I can live with that.

Thanks John. I've got that article bookmarked. I'm still confused.

Here's the article Nick referred to.

AHA! From that article:

"Let’s say you have a 50-inch TV that has a resolution of 1280 by 768 and the vertical height of the display is 24.5 inches. To get the viewing distance, divide the height (24.5-inches) by 768, and then multiply by 3,400. For this example we get a viewing distance of 108.8 inches. So, for that 50-inch, 768p resolution TV, we should sit about 9 feet away. Sit farther than that, though, and we won’t resolve the detail. Sit 9 feet away from the 1080p display and it won’t look any better than the 768p display."

Nick, I hope you won't take the following as criticism for that is not how it is meant. I'm grateful for you bringing this whole thing up. I'm learning stuff here.

I see where Nick was confused, or at least confused me. The example above shows that if you're sitting the optimal distance from 768p set (e.g. 9'), then at that distance, a 1080p set won't look any better. BUT, if you move to the optimal distance for a 1080p set (77.13" = 6.43'), a 768p set should look worse than the 1080p set.

The point is, if you're locked into sitting a specific distance from your HDTV, there is no need to spend the money for an HDTV with a resolution greater than what is optimal for that distance.

I have owned two HDTVs, a 43"/720p set, and now a 56"/1080p set. According to the formula above, the optimal distances for these sets is 43"/720 TV is 8.3', and 7.2' for the 56"/1080p TV. Interestingly, I have been sitting between 7 and 8 feet from both. Pure dumb luck I assure you.

Equally interesting is that if you compare the formula in the article Nick provided to the formula in the article I provided, for a 56"/1080p set, one recommends a viewing distance of 7.2', and the other 11.43'. I'm so glad there is agreement on this issue.

So.....from all of this I gather that a chair on rollers is advised!

LOL! Or, something, like a car seat, on rails. Very loooooooooooooooooooooooooong rails.

Guys, I know that you're kidding, but of course the bottom line of those articles is that with a given HD set you have to sit closer when you're playing 720 or 1080 material than you'd need when playing 480 material, in order to be able to see the full resolution. You don't move back when playing 480 on the set, you just don't get the HD resolution at the same distance.

Still trying to understand all this, John. When you feed a 480 signal or, for that matter, a 1080 signal to a 720p HDTV, isn't the signal converted (scaled?), by the TV, to the TV's native resolution (i.e., in this example, 720p)?

Actually, we're joking (sorta) about needing seating with wheels or rails because the two articles disagree about the optimal seating distance for a given set of any resolution. That's why I said:

Quote:

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...if you compare the formula in the article Nick provided to the formula in the article I provided, for a 56"/1080p set, one recommends a viewing distance of 7.2', and the other 11.43'.

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HOWEVER! I must stand corrected (while remaining seated). The formula in my article was meant only for 720p sets not 1080p. With that in mind, for a 720p set, the formula in my article recommends a seating distance of 11.43' and the formula in Nick's article recommends 10.8', which is only a difference of about 8.5 inches. So, actually, the formulas don't disagree to any significant degree. Apologies to all.

So we only need short rails then ?

Whew, that's a relief.

I think y'all need a short bus.

Yeah Jack, those two rules-of-thumb are in close agreement on your 56/720 example, and also with the S&V graph, which shows about 11'. On your first point, note that it's the "real" resolution of the program material, which isn't increased by upscaling, which limits the observable resolution. For example, the S&V article states in discussing an example(beneath the first graph): "...so a high-def program on a 720p HDTV-or a 720p program viewed on a 1080i or 1080p HDTV...", indicating that the 720 program material is the controlling factor with regard to resolution on the 1080 set.

Yeah, I vaguely had the concept that 480 or 1080 material converted to 720p wouldn't quite look the same as 720p material on a native 720p set. Somthing is lost in translation, I guess (filling in pixels; removing pixels?).