SI Black Diamond clone? - Page 3 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #21 of 47 Old 08-07-13, 06:01 PM
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Re: SI Black Diamond clone?

THANK YOU very much for all your trouble, info, pics and videos!!!
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post #22 of 47 Old 08-07-13, 06:20 PM
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Re: SI Black Diamond clone?

I have a question...

It is well known that white color is the most forgiving and easy to use in the calibration process. How about black color? Did you try to calibrate your projector? Did you notice any undesirable and unrecoverable color shifting even after using RGB or cms controls?
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post #23 of 47 Old 08-07-13, 06:25 PM
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Re: SI Black Diamond clone?

This is great Rob!

Thanks for your pics and videos, I have to say I am impressed, though I have some questions. You mentioned you used a 7000 lumen projector when testing the Rosso black projection material, did you use that projector for all the other tests? If not, what projector was used during the other tests? As you demonstrated, it's possible to get a good picture using a bright enough projector and a completely black projection surface, I'm asking since the black screen test and the completely black surface test was quite similar.

I'll get back to you tomorrow after some sleep, can't process all this information you have given us this late at night, but I appreciate all your effort you have put down on this, it's great!

/Patrik
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post #24 of 47 Old 08-07-13, 06:39 PM
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Re: SI Black Diamond clone?

Latest diy black-screen test - best results yet. I'll explain in a minute.
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post #25 of 47 Old 08-07-13, 07:19 PM
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Re: SI Black Diamond clone?

Good question Yiannis. The reason they say white is "forgiving" is because, in light, it is a mixture of all three primary colors your projector uses to make up its image. As odd as it sounds. Mixing rgb light gives you white. In pigment, like paints, they appear the color they are because that pigment is most efficient at reflecting that color. Something that is great at reflecting red, will appear red. That is as far as my understanding of how eyes work goes. Red isn't red, it just reflects red light into your eyes. White is easy because it reflects the broadest range of colors and doesn't block any of the primary colors. Adding color will have the effect of enhancing the reflection of one of the colors and blocking another. Yellow, for example reflect green and blue but blocks red (or something like that). This leaves is in a pickle for screens because projectors can't project black so unless its dark, the only way to get black is by add pigment to the screen. Now, white isn't the only thing that has good reflection across the visible light spectrum. Some metals like aluminum and silver can reach 98% of the visible spectrum. This is why grey screens are ideally a mix of white or light colored paint and aluminum paint. Make the same grey color using black and white and you will see a drop in brightness. The key take away is that 2 aspects have and impact. Color is 1. The material properties are the other. There is also a difference between a color, and something that looks the same, but isn't - like black screen material. It doesn't work like other paint methods. The dark color may look grey or even black but it is actually multiple layers which are separate that trick the eye into seeing a single color. In this case, there is a light diffusing layer at the front, which is a translucent white. This layer is the screen surface for all intents and purposes and is as "forgiving" as any white screen. Underneath the light diffusing layer is a layer of tint which on its own would be a translucent black. This layer ideally lets a good portion of light pass too. When the projector light shines through the translucent white layer, you can see the black under it. As black is an absence of light, think of it as the projector just being off wherever the screen should be black. With a white screen, with the lights on, that would look grey at best. With the black tint showing, it now looks black. Behind the tint, there would ideally be a further reflective layer that covers the visible spectrum. Tint can let through 5% to 95% depending on which one you use. This will have the effect off letting more light and therefore gain through or less light and more tint for higher contrast. The front may look gray or black but it is really 2-3 separately layers which are white, black or silver. No of these will have the affect of change the color balance in a noticeable way.

Now, these screens are for bright conditions. In such conditions, white is actually the least forgiving. It is very difficult to achieve anything but a washed out look, let alone accurate colors. It is only the most forgiving in a dark room. As for calibration, I find these days that if you have a bright enough projector, you can achieve a watchable image on almost any flat, even solid color. As long as there is some reflectivity and light diffusion. Some of my projectors have settings for different colored walls including red, green, grey, beige, blackboard and whiteboard. I think that is a long winded way of saying, no, no issues with calibration from color shift. Paints with mica pigments have more issues with color shift I believe. If you can make black work, I think colors look much brighter with better contrast.
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post #26 of 47 Old 08-07-13, 07:52 PM
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Re: SI Black Diamond clone?

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Daylightuser wrote: View Post
Now, these screens are for bright conditions. In such conditions, white is actually the least forgiving. It is very difficult to achieve anything but a washed out look, let alone accurate colors. It is only the most forgiving in a dark room. As for calibration, I find these days that if you have a bright enough projector, you can achieve a watchable image on almost any flat, even solid color. As long as there is some reflectivity and light diffusion. Some of my projectors have settings for different colored walls including red, green, grey, beige, blackboard and whiteboard. I think that is a long winded way of saying, no, no issues with calibration from color shift. Paints with mica pigments have more issues with color shift I believe. If you can make black work, I think colors look much brighter with better contrast.
Thanks again for the info!! It's a bit out of my league of knowledge on the matter but nevertheless it's always useful learn new things..(the first part kinda reminded me a paper of XRite's which talked about colors and perception).

I can see your aim is practically to achieve a high contrast screen for very bright environments. However, for obtain such results you used many many lumens. Now, if we are going to stick to H.C. projectors, i think it would be quite difficult to find so much light at affordable prices. I believe, nowadays, a ~2000 lumens projector has become the standard to industry and that due to 3D. Then, it's the matter of size as well...how many lumens would you need to fill up according to standards a 100'' black screen?
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post #27 of 47 Old 08-07-13, 07:53 PM
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Re: SI Black Diamond clone?

I only used the 7000 lumen projector for the Rosso after failing to get an image with anything else. I was using a 2500 lumen projector for the rest of the tests. There would not be much achievement in creating a surface that didn't work without 7000 lumens. That said, I haven't tried the latest versions with my lower brightness projectors in the 700 lumen range. I can if you are interested to see how they do. My guess is that they will work with some room lights on but probably not with sunlight shinning in like in these pics. With the Rosso, even 7000 lumens wasn't enough...

Now, check out the last set of pics. I have made more progress. This DIY black-screen has a material front layer instead of paint which is a lot smoother and gives much better results. I started with a piece of white translucent light diffusing material. On the back, I added 7 layers of aluminum paint (which was how much it took to stop it being totally transparent for some reason. The front appearance then changed to dark grey. Not dissimilar to the black diamond 1.4 gain material in color. Even that didn't stop light slipping through so I added a layer of black paint to the back which did the job. This changed the front appearance to a darker grey. Almost black which is the effect we are going for. The first pic shows the appearance when not in use. I left a bit without black so you can see the difference.

Next are 4 pics of the fabric in use. I know it looks like I'm obsessed with that movie "the hunger games". I'm not. It is just one on Netflix that I know is 2.40:1 so you can see how good the blacks are on the black borders. Weirdly, the angle of the pic makes it look like I have a deformed hand which I don't. You can see in the later pics that my hand is normal, not a weird mangled claw. The last pic shows it working next to a piece of white material which, as normal, looks washed out in this light. It sounds like I hate white screens. I don't. I use one myself when the room is 100% dark for movie night. It is just necessary to remind us what we are comparing the black-screen too and that no white screen gives a good image in these conditions. We are talking blinds open during a summers afternoon here.

I should post a pic with the 7000 lumen projector on white to show that the image still looks washed out in a bright room. Anyway, the latest black-screen attempt is easily the best to date. I'll post some videos when I get around to it. I love the way it looks though. Its so bright, clear and smooth. I'm tempted to make myself a new screen with this method before I've finished my experiment but I'll wait. I will take delivery of some new tinted film, reflective film and light diffusing film in a few days and that will be the real test. Practically no hot spotting so far btw. Also, the end result won't rely on my painting skill (thank god) so it will look more professional and less like something a 4 year old would stick on the fridge with a gold star.

Also, I spoke to the micro louvers company today. They came back and said that the largest they make them is 55 inches. I said "I know, that's why I asked for a quote on a custom order". They said "oh yeah". So they have gone away again to get me a price on a larger piece. I am not that hopeful with this company though. I'm not dealing with rocket scientists. I may have to find a new manufacturer...

Look out for a new you tube video of the latest black-screen material in a little while. And if anyone can steel a privacy screen for testing, I would love to know if it works in the mean time.

Rob
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post #28 of 47 Old 08-07-13, 08:01 PM
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Re: SI Black Diamond clone?

The lowest I have tried the black screen on is a 2500 lumen projector. I have some lower powered devices too. I will try them and post some pics so you can see. They will work, it's just a case of how much light they let you get away with. In general, if you have a really bright room (like sun light). You will need a brighter projector than 2000 lumens. This is true no matter what screen you use or how much you pay for it. Put the money into more lumens first. It is true that my aim is to get good contrast in a well lit room. I use a 3000 lumen projector for movies. Now, there are degrees of benefit. While nothing will make 2000 lumens look great in sunlight, the black-screen might give you a none washed out image with good blacks with a couple of room lights on in a scenario where you otherwise needed total darkness. I doubt there are Many projectors where this method wouldn't work at all. These aren't low gain screens.
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post #29 of 47 Old 08-07-13, 09:37 PM
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Re: SI Black Diamond clone?

Just for you.

I tested the black-screen with my smallest projector. This thing is a real piece of cr*p. It was meant to put out 700 lumens when new about 6 years ago. It hasn't had a new bulb since then or anything so I think you'll agree this is a good test to see if the black-screen works with lower powered projectors.

There is no daylight at this time so the ambient light is from two room lights. One above and one to the side. Both fairly bright. More ambient light than you'll see in any BD test!

Check out the size difference between the 700 lumen and the 7000 lumen projectors!

I included a pic showing how this little thing struggles to produce even a small image on the white wall/screen in this level of brightness. On the old black-screen, it manages a respectable image, even on some of the difficult dark scenes in the hunger games. With the new black-screen material, the results are even better. I also show this compared to white material for comparative purposes. Bottom line is that is works and lets you use a low powered asthmatic projector with the lights on. It gives much better results than the white wall or white screen, even against a much smaller image. On the black-screen, the device is putting out a respectable 90 inch image which was unheard of with this device in anything but darkness.

Here is a link to a video clip to so you can see the conditions.


If your projector is less bright than this, time for a new one!

Rob
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post #30 of 47 Old 08-07-13, 10:43 PM
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Re: SI Black Diamond clone?

Thanks again for the info and the analysis. You 've said before that you have also the Sony screen. I would be very interested to read your feedback against the black screen.


(pics would be most appreciated)
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