DIY Screen - 155" Diagonal - Advice Needed

The room is a dedicated theater, 7.1 audio and a 2 channel stereo system as well. The projector is shelf mounted and is 23 feet from the screen. The room measures 28' deep X 24' wide. The lamp mode is set for a dark room in the natural setting. This is the brightest of the dark room modes. Both cinema modes are a little dim for my taste. The lighted room setting of "dynamic" is fine for sports, but tends to make the colors a little bit hot. Although, this setting does add a lot of sizzle to the picture! The Panny throws plenty of light!
The one area that could be improved upon would be the detail in dark (dimly lit) scenes. I have exit lighting (LED green) ceiling mounted at both entrance doors at the back of the room. The exit lights do cast a very, very small amount of illumination.
It is not that I do not like the screen, but it was 3 years ago when we built our house. A lot of research was done at that time on screen paints and mixtures. We thought that by now someone had discovered a much better (new & improved) formula for us DIY'ers.
Even though the screen to the eye looks white, it is actually gray/silver.
I would post a picture or two if that is possible.

Thank you for your help!

According to the review of your PJ at projectorcentral with a screen of your size you are getting anywhere from about 11 fL. of light in Vivid Cinema mode to around 19.6 fL. in Dynamic mode. I'm not sure where your dark room mode fits in between those two. It's at times like this that a simple low cost light meter can really come in handy. Those figures also assume regular brightness mode. I saw no figures on what percentage of light you lose when going to low-lamp mode, but it's usually around 25%. Most people seem to prefer an image around 12 fL. though some can tolerate less - it gets quite subjective.

Oleson said:

The one area that could be improved upon would be the detail in dark (dimly lit) scenes.

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If you can't see the detail in dark areas of the image (assuming it's really there to begin with) either the PJ needs to be properly calibrated with a good calibration DVD (it's amazing how many people forget to do this) or your screen is too dark a gray and is crushing blacks.

Do the black areas of your image appear black to you, or a dark gray?

I would guess your screen is about a N8 shade of gray, but this is a pretty wild guess. If you are getting "blooming" in your colors in the brighter modes this may indicate that the mica in the mix isn't being controlled well enough since this is one of the side-effects I mentioned before.

It would be a help if you could post some images that are representative of the way your screen looks to your eye. I think you have to have at least 5 posts here before your can post links.

While we are always looking for ways to improve image quality, there are only so many things that can be easily done in the home environment. I'm not suggesting all of them are exhausted, just that we haven't found them yet.

To be honest, your screen is a bit large for the light output of your PJ in it's best image quality modes.

The Black Widow paint looks impressive, to be sure.
Could I simply roll over my current screen paint, or would it need to be primed first?

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It is, but it's too dark a mix for your current HT setup.

We did not realize the mica/pearl based formula caused problems.

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There are some pretty wild claims for some mica-based mixes on other forums. We look into the science behind screen technology here and the problem with using mica as a reflective element in a screen mix is that it refracts light as well as reflecting it. This refraction breaks up light into other colors than the one projected and can result in bright areas of the image seeming to "shimmer" or colors to "bloom". If too much mica is used the screen can also hot spot and the center of the screen image will appear brighter than the edges. Also, the image can lose brightness as one moves away from the center seat which is on-axis with the PJ.

Is their a protective "top coat" that can be applied?

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None that we can recommend so far, all the clear finishes we have tested have turned yellow over time and shifted the color of the screen.

Even though I don't have the exact paints you used to make your screen (the Behr white pearl has been discontinued), I will try to make up a batch of something very similar and get a color reading. We can go from there. :T

Oleson said:

Blooming / Hot Spots.....to my eyes, none present, and I am a critical viewer.

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Glad to hear it. How much mica-based paint is too much also varies with the gloss levels of the paints used.

Just Watched Roy Orbison - Black and White (Great Concert), the black level appears pretty good. Blacks are black, but at times are solid black so as to lack detail...assuming the detailed content is present in the video in the first place.

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OK, blacks are black, which is good, but it could mean they are too black and you are losing detail. Did you calibrate the PJ to that screen?

Did you ever try a lighter screen? If so, how did the black level look on it?

The Panasonic PTAX-100U was purchased based on the review at Projector Central. It is the same as the -200U. Yes, to my eyes the cinema modes are just a tad dim. Perhaps this is due to 700 hours on the lamp, although I never cared for either of the cinema modes.

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You will have some dimming of the lamp with 700 hours on it, but I can't tell you how much. I have heard that a lamp will dim 50% over it's life span, but I haven't seen any break-down of that, only that much of it happens in the first half of the life of the lamp.

Absolute perfection is not my goal as it is unattainable. But the incremental pursuit of audio/video nirvana is my desire as a hobbyist.

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Ahhh... a realist. :T

Now that this is post #5, perhaps we'll upload a photo or 2!

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We usually use an off-site photo hosting service like photobucket or imageshack, but HTS will let you upload them here. I don't know how that works, I've never done it. :blush:

Thanks again for all of your help and input.

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Glad to be of service. :nerd:

Photos!

My middle aged brain finally broke the code!

Most of the screen images are with the projector set on Dynamic with ambient room lighting. This is not how we utilize the projector, but had to use this setting in order to get my camera to get a decent shot.

The black and white shots are at the normal brightness setting for a dark room.

Any thoughts/ideas, or general feedback (even critical in nature!) would be welcome.

Thanks!

Wow! That is an awesome HT! :T

I have a few questions.

1. Has your PJ been calibrated to that screen?

2. Have you ever tried a white screen (such as the Kilz2 before the top-coats)?

3. Are the photos truly representative of what you are seeing with your eyes?

4. In the 3rd photo from the left it appears the screen is hot spotting. This could be because of the way the camera exposed the photo, the PJ or the screen. What mode was the PJ in for this photo? I assume it was projecting a white image.

5. Unless it's the camera doing it (it can be a problem getting photos that really appear the same as the screen looks to your eyes) the rest of the photos seem to have a compressed contrast range with details missing in both the blacks and the whites.

I hate to sound like a broken record, but the first thing to do is to double check that the PJ is properly calibrated to the screen.

PJ has not been calibrated. At least not by a pro. I did a number of adjustments early on to get what to my eyes was the most natural picture.

Have never tried a "white" screen, only the one in the you saw in the photos. Do you think that screen should be a shade or two lighter? Or even white?

All photos, with the exception of the black and white pictures were shot with the PJ at it's brightest setting (Ambient light/Dynamic setting). This was the only way I could get a good photo without timed exposures (too complicated for me).

The black and whites were dark room setting with natural lamp mode. This is one step up in brightness from the cinema modes. Using timed shutter speeds the camera did OK.

You reference the 3rd photo. That is a standard DVD. The scene is dark and it was a challenge to get any photo at all.

The camera is a close representation of the actual viewing experience, but as you know, the camera does not do justice to the images. The screen does look somewhat better in a live venue.

Compression? Is their a way to fix it? Suggestions here are always welcome and encouraged.

Photos of the complete theater were sent so you could see the total environment......PJ location, wall colors, general layout, etc.


We put a lot of thought and effort into the entire home theater. It was totally a DIY project.

Thank you for the kind words!

Oleson said:

PJ has not been calibrated.

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OK, this could well be the culprit right here. Some DVD's, like "Cars" and "Terminator 2", have a THX calibration program on them that will let you do basic contrast and brightness calibration, but I highly suggest investing in either the "Digital Video Essentials" or "Avia" dedicated calibration DVD's; or perhaps both since some prefer one over the other. These discs have special images that help you bring out the small details in blacks and whites as well as set colors accurately (although some people prefer to set color "by eye"). Calibrating your PJ to your screen should be your next step in improving your image quality. It really does make a difference.

Have never tried a "white" screen, only the one in the you saw in the photos. Do you think that screen should be a shade or two lighter? Or even white?

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I was just wondering. Here is my thinking; if details in whites were OK, but details in blacks are being lost (on a video calibrated HT) that would mean the screen was too dark a gray for the brightness of the PJ. If that was the case I would suggest a lighter gray screen mix such as Elektra™ N8.5 or Cream&Sugar™ (a N9 mix). BTW, N levels run from N0 for pure black to N10 for pure white. About the minimum N difference that can easily be detected by eye is a N0.5 difference. Before I could make a comfortable recommendation for a new screen for you I would have to make up a test mix that is similar to your current screen which I believe is close to N8. Another "wild card" is that I'm not sure how reflective your screen is with 40% white pearl paint.

While I will try to make that mix up soon, I truly believe your problem with black details may stem from the PJ not being properly calibrated.

All photos, with the exception of the black and white pictures were shot with the PJ at it's brightest setting (Ambient light/Dynamic setting). This was the only way I could get a good photo without timed exposures (too complicated for me).

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I understand, but photos of images using a different setting than you normally use for viewing probably wouldn't show the same detail lose you are describing. This will still work as long as you describe the difference between a photo and what you are seeing or having a problem with.

The black and whites were dark room setting with natural lamp mode. This is one step up in brightness from the cinema modes. Using timed shutter speeds the camera did OK.

You reference the 3rd photo. That is a standard DVD. The scene is dark and it was a challenge to get any photo at all.

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Perhaps my browser (Opera) is displaying your images in a different order. For me, the 3rd photo from the left is the one with a bright white screen with no realistic image at all. It looks like a solid white image.


The corners of the screen are dimmer than the center of the screen, but this could be caused by the camera over-exposing the screen and not something that could be detected by eye. Is the screen being illuminated by the PJ in this photo, or just room lights?

I also assume that a star filter was used in the shots displaying your HT. Cool effect!

The camera is a close representation of the actual viewing experience, but as you know, the camera does not do justice to the images. The screen does look somewhat better in a live venue.

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Yep, the camera, in my experience, usually brightens colors, deepens blacks and generally heightens (or compresses) image contrast to what it thinks the picture should look like according to it's computer brain. Even if a photo doesn't directly show the problem one is having it is usually possible to amend the photo with text describing how it actually looks if the photo is at least close to what is being seen by eye.

Compression? Is their a way to fix it? Suggestions here are always welcome and encouraged.

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The camera could be doing this, or as I think the case is here, the PJ doesn't have the brightness and contrast set properly for the screen in use. This can result in compression of the contrast of the image so that instead of a large number of gray levels being visible a lesser number are. This will show up as lose of detail in blacks, whites, or both. If you calibrate that PJ I think you will see quite a difference in image quality.

Photos of the complete theater were sent so you could see the total environment......PJ location, wall colors, general layout, etc.

We put a lot of thought and effort into the entire home theater. It was totally a DIY project.

Thank you for the kind words!

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I really do think your HT looks great, I wasn't trying to shine you on or anything; about all that's missing is the smell of popcorn! :bigsmile:

Thanks again for your help.

The PJ was only calibrated with minor adjustments using my own eyes, much like I do on my flat panel TV's. Nothing elaborate or scientific. Just enough to make it look as good as I could.

Can you recommend a blu-ray test/set-up disc? Perhaps this would provide a starting point for calibration (or better yet, an ending point!).

Picture #3 - this is simply room lighting (yes, a star filter was used) with stage floods shining on the screen. PJ was off. Any hot spots/dim spots are from the floods!

Camera effect - there was some blooming noticed on the camera shots that absolutely was not on the screen. I did a double take. Your analysis is correct in the cameras brain is overcompensating for whatever it thinks is the correct exposure.

My Panasonic owner's manual states a throw range for a 150" screen from 17' to 30', for what that's worth.

Popcorn's almost ready....what will you have to drink with that, sir?

Oleson said:

Thanks again for your help.

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You are more than welcome.

The PJ was only calibrated with minor adjustments using my own eyes, much like I do on my flat panel TV's. Nothing elaborate or scientific. Just enough to make it look as good as I could.

Can you recommend a blu-ray test/set-up disc? Perhaps this would provide a starting point for calibration (or better yet, an ending point!).

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This is the way most people "calibrate" their projector since this is what most have done with their older TV sets. Most HT PJ's have far better controls than the old CRT TV's and their settings really do need to be calibrated to get the high image quality they are capable of. Wbassett and Mech both have higher quality PJ's, perhaps they can jump in here and give you a few tips. My PJ is a lowly presentation model and has very poor settings controls so I can't use a calibration DVD to it's fullest potential.

The last I looked, DVE and Avia were the favored calibration discs. Both are available in HD versions. I just searched Froogle.com for them, here are links to the lowest prices I could find for them (actually DVE is available for a few dollars less from Amazon.com, but you might be able to save more than that on combined shipping if you decide to get both discs).

Avia 2 $32.79
http://www.pacificdvds.com/ExternalSearchResult.aspx?ProductID=94415

DVE-HD $16.92
http://www.pacificdvds.com/ExternalSearchResult.aspx?ProductID=91756

While this calibration FAQ is about using a dedicated device for generating the patterns, it is still a good page to tell you the basics of TV or PJ calibration. The calibration DVD's mimic the test patters of this device with images from the DVD. Warning - there is enough info here to make your head hurt. The calibration DVD's take you through this stuff one step at a time; it's easy, but takes a while.
http://www.accupel.com/Calibration_FAQ_f.html

Picture #3 - this is simply room lighting (yes, a star filter was used) with stage floods shining on the screen. PJ was off. Any hot spots/dim spots are from the floods!

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The more I looked at the photo the more I thought this would be the case. Tried to throw a ringer in there huh?:sneeky: Just kidding!

Popcorn's almost ready....what will you have to drink with that, sir?

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Back in the day, that would have been an extra large Coke as well as at least one bag of Sugar Babies. Ahhh, those were the days.
http://www.oldtimecandy.com/sugar-baby.htm