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Black Widow™ itself or just the AAA? BW™ is .87, which we always round up to .9. The AAA? I have no idea.

As for what the N value of the paint, I'm not familiar with it. If we did do a measurement, we'd include L*a*b* values and the L value would correspond closely to the Munsell value.
 

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I just looked at the gain charts that Mech did for BW™, there are 4 of them that used two different light sources and four different light intensities. Three of the tests showed an on-axis gain of 0.88 and one showed 0.89.

If I'm reading the identity of your paint correctly Jase, (here) it's approximate N level would be N9. Their paints don't use aluminum as the reflective agent.
 

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I just looked at the gain charts that Mech did for BW™, there are 4 of them that used two different light sources and four different light intensities. Three of the tests showed an on-axis gain of 0.88 and one showed 0.89.
That'll teach me to go from memory. :doh: And I didn't realize he was talking about DIY Theater paint. I must really be slippin'!
 

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I just looked at the gain charts that Mech did for BW™, there are 4 of them that used two different light sources and four different light intensities. Three of the tests showed an on-axis gain of 0.88 and one showed 0.89.

If I'm reading the identity of your paint correctly Jase, (here) it's approximate N level would be N9. Their paints don't use aluminum as the reflective agent.
Harpmaker,
I thought that the BW was a darker mix(N7.5 or N8?) and C&S is N9. We add C&S to BW to make it lighter and N6 to C&S to make C&S darker.

Am I missing something?
 

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Discussion Starter · #6 ·
2 topics there sorry im a lazy kiwi. I think 1 reference was to BW the gain part and the other was reference was about my current screens N value. Also If I read correctly BW will make your screen appear about .5 up the N scale i.e. like an eight which would give you whites looking like an 8 while retaining the 7.5 black levels? also with a gain of .9 compared to a OTS grey of N7.5 being nearer .7?

I am new to all this so I may have miss interpreted all of this im sure Mech or someone will clear up this one for us

cheers Jase
 

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TheaterQuest and Jase, you are both correct.

TheaterQuest, I believe you were thinking I was talking about one of our mixes when I said the shade was N9; I was talking about DIY Theater's commercial light contrast screen mix. I got that info by determining the shade of gray they have displayed for that mix on their site with a color picker tool, it may not be correct.

Jase, correct, BW™ is a N7.5-7.6 mix - this is it's actual shade of gray. It will absorb light, all light from all directions, just like a regular flat finish painted screen the same shade of gray. While under projection (a very directional form of light) it will appear to work like a flat finish painted screen ~N0.5 lighter in shade because the aluminum is reflecting more light than the paint alone; this means both whites and blacks in the projected image will be lighter than if a N7.5 flat finish paint was used. NO PAINT can reflect more white, but leave blacks alone - it's physically impossible with a simple paint. The key to the success of BW™ is that it will absorb off-axis light (relative to the PJ) like a N7.5 while showing an N8, or slightly brighter, image. BW™ doesn't claim to break the laws of physics, but rather uses them to the advantage of the viewer.

Just as a side note, the official full name of BW™ is "Black Widow™ PFG". The PFG stands for Pigment Free Gray since the original formula Bill and Mech came up with contained only aluminum paint and a white base paint with no tinting pigments. Unfortunately, the aluminum paint they used was rumored to be discontinued, and it does have very limited distribution, so another aluminum paint had to be found. To make long short, the final aluminum paint was Auto Air Aluminum-fine and it was found to actually need some added tint to compensate for it providing a blue push when added to white paint alone. I believe the PFG was kept in the full name because another similar grayish "metallic" paint had a complicated pigment-based "color component" and the desire was to be able to easily tell them apart by just the name.

As for the gains of regular flat paints, we haven't done much testing of that, but we need to do more. A truly flat finish N7.5 paint (100% diffusive) should have a gain of about 0.48, but this isn't the case because very few paints are truly 100% flat - they do have at least some gloss/sheen to them. Mech measured the gain of Valspar Ultra Premium interior flat enamel paint in a N7.5 shade and it was 0.75 across the board.
 

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Discussion Starter · #8 ·
nice one thanks.

So what is the point to use anything but white?

Why would you use an N7.5 then try and make it upto N8 with reflective additives .why not just use N8

Or is it the fact that if you use darker grey it can have more ambient light without fading out but you need the reflectives to get a higher gain so the picture is still bright enough.

Some screen paints claim ( pro ). that black get blacker and whites get whiter and you get a brighter more vivid poppy picture with more contrast due the grey making blacks blacker while the reflectives make it brigher and whiter??????????????????

cheers Jase
 

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nice one thanks.

So what is the point to use anything but white?
A gray screen can add to the perceived contrast of the projected image if either the PJ has problems in that area or because some ambient light is present which is killing image contrast. With todays run of PJ's producing great black levels (in a "bat cave") the only reason to use a gray screen is if there will be enough added light in the room to severely impact image contrast. Most people though don't have a dedicated home theater and instead have their PJ and screen in their living room or multi-purpose room that many times has light colored room surfaces. In that scenario even the best PJ can use some help in producing black blacks and a gray screen of some type is the answer, along with controlling as much of the ambient light as possible. The key to understanding this is to realize that the projector can't project black. All it can do is not project any light into a portion of an image that is black (the PJ's failing at this are the ones that need a gray screen even if used in a "bat cave"). The darkest black that a screen can produce is the color of the screen itself. Think about that. If you are using a white screen that means there can be NO light hitting the black parts of the image. ANY light, no matter the source, that hits that area of the screen will result in a grayish black, which usually will also appear as a contrast deficient image. If that is happening a gray screen can help, but only so much.

Why would you use an N7.5 then try and make it upto N8 with reflective additives .why not just use N8
A true N8 screen will not absorb as much ambient light as the N7.5 screen with reflective additives and thus not provide as deep blacks.

Or is it the fact that if you use darker grey it can have more ambient light without fading out but you need the reflectives to get a higher gain so the picture is still bright enough.
Correct. :T In the scenario above, if the person had enough lumens they wouldn't need the reflective screen, but could simply use the flat N7.5 painted screen.

Some screen paints claim ( pro ). that black get blacker and whites get whiter and you get a brighter more vivid poppy picture with more contrast due the grey making blacks blacker while the reflectives make it brigher and whiter??????????????????

cheers Jase
Be careful of claims. Reputable companies will provide some proof (other than screen photos) of screen performance (usually gain charts).

It is relatively simple to create a screen mix that produces blacker blacks (just darken it a bit) and also produce whiter whites (make the screen glossier); but doing this WILL shrink the viewing cone of the screen and perhaps even make it hot spot. We don't see any sense in making a screen that has all these fantastic (supposedly) statistics, but really produces a horrible picture.

I'll give a for-instance; below is a photo (not taken by me) of a Stewart FireHawk G3 screen. The reviewer just thought it was the best thing since sliced bread, but I would have a hard time watching anything on this screen for long because it hot spots. Notice that the white uniforms of the players in the center of the image are far brighter than the same uniforms at the edge of the screen - this is hot spotting.

 

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Discussion Starter · #10 ·
awesome thanks getting the puzzle more and more now. The reason for the most confusion was when above in post it was said that adding the additive would take the N7.5 into looking like an n8 which would make whiter looking whites but would also make black lighter so no gain over standard N8.

In the last post you said you can have paint by greyness make blacker blacks and by gloss make it whiter whites but you may get hot spots. so I take it the reflective additive is to achieve the same without hot spotting. That contradicts the above???????

dump kiwi I am
 

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awesome thanks getting the puzzle more and more now. The reason for the most confusion was when above in post it was said that adding the additive would take the N7.5 into looking like an n8 which would make whiter looking whites but would also make black lighter so no gain over standard N8.
The key to understanding the difference between BW™ and a N8 flat gray paint is that while both will work about the same under projection, the BW™ will handle more ambient light than the N8 provided the ambient light is coming from any other direction than straight behind the projector. I know it's kind of a hard concept to wrap your mind around.

In the last post you said you can have paint by greyness make blacker blacks and by gloss make it whiter whites but you may get hot spots. so I take it the reflective additive is to achieve the same without hot spotting. That contradicts the above???????
A flat gray screen makes everything darker, blacks and whites; but there is a type of optical illusion in effect with a gray screen. When we see a picture of snow or a white dress or uniform our brain tells us that it is truly white even though it may really be a light gray AS LONG AS there is nothing "whiter" in the image that the gray screen. This is why a gray screen can work and look great until you put a white piece of paper (or other bright white object) on the screen; then the whites on the gray screen will show up as muddy, dull whites. Take the white object off the screen, blink a few times, and the whites on the gray screen will be back to looking white.

Reflective particles increase gain in a different way than gloss does. You can get hot spotting with them as well, but you usually run into other negative optical artifacts first (like graininess or shimmering in bright areas of the image).
 

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Discussion Starter · #12 ·
Is it correct to say then, blacker blacks and whiter whites in a reflective based screen, if the word perceived is added and the gain is above the compared product i.e. compared to plain grey of same N value or screen with a lower gain than the claiming screen uses. I.e. the brighter image due to the reflective adding more gain gives you a higher perceived white. ( brighter picture = whiter perceived white ).

I notice some manufactures tell more truth and with a .9 grey screen sat better blacks colours contrast etc with almost as white whites. ( they are comparing here I presume to white screen with gain of 1, which of course they dont mention )................................

Jase
 

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Is it correct to say then, blacker blacks and whiter whites in a reflective based screen, if the word perceived is added and the gain is above the compared product i.e. compared to plain grey of same N value or screen with a lower gain than the claiming screen uses. I.e. the brighter image due to the reflective adding more gain gives you a higher perceived white. ( brighter picture = whiter perceived white ).
It can be correct to say that, but it depends on what they are comparing the reflectively enhanced screen to. Adding gain to a screen will make the image brighter compared to a Unity screen (a white screen with a gain of 1.0), but blacks will be the same amount brighter as the whites - everything is brighter. Compared to a flat finish screen the same N level as the reflectively enhanced screen the reflectively enhanced screen won't have deeper blacks, but it will have whiter whites AND whiter blacks; it will however have the same ambient light absorption as the flat finish screen the same shade of gray.

I notice some manufactures tell more truth and with a .9 grey screen sat better blacks colours contrast etc with almost as white whites. ( they are comparing here I presume to white screen with gain of 1, which of course they dont mention )................................

Jase
Yeh, it would help if the listed exactly what screen they are comparing their screen to. If it isn't stated it's relatively safe to assume they mean compared to a Unity screen.
 

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in the picture of hotspotting is displayed on my very glossy laptop I cant actually find anything in the room. How is this possible if it is a grey screen?
You lost me here Jase. I don't know what you mean. :scratch:

The Stewart FireHawk G3 screen is a dark gray screen (I forget it's N value right now) that has a special reflective coating applied to increase it's gain. It does work, and is quite popular, but, in my opinion, from the photos I've seen of it it exhibits the negative aspects of having too much gain (hot spotting and very limited viewing cone). Some people think it's the cat's meow.
 

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Discussion Starter · #16 ·
ok I better give up I think b4 i drive you nutts as b4 it was said that the pj doesnt produce a black picture it just puts no light in a black part of the picture so why should blacks change at all with a higher contrast screen if there is no light on it????????????????????

ambient light vs projected light are different how??? is light not just light? how do the react different???

thats my final qs

cheers for the help trying to get me to understand it all

Jase
 

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ok I better give up I think b4 i drive you nutts as b4 it was said that the pj doesnt produce a black picture it just puts no light in a black part of the picture so why should blacks change at all with a higher contrast screen if there is no light on it????????????????????
Oh don't worry about driving me nuts, that happened a long time ago! :dumbcrazy: :D

Black levels change because light IS hitting the screen in those black areas. Very few PJ's, if any, truly block all extraneous light from the black areas of the projected image. I'm not even sure it's physically possible when using a lens. The point is that many PJ's do in fact project a lot of light in the black areas and thus blacks look gray on a white screen. A gray screen will absorb at least part of that grayish black and make it look blacker. The same screen will absorb the same amount from white areas of the image (and all colors and gray levels in between), but we humans are used to compensating for dim whites (that optical illusion I mentioned).

If there was literally no other light in the room than what was coming out of the PJ's lens, and all the theater room surfaces were covered in black velvet so no light bouncing off the screen could reflect back onto the screen, there would be no reason to use any other screen than a bright neutral white with no gloss whatsoever. The problem is that very few people want to build such a home theater. In the real world some light from the screen is reflected back onto the screen which lessens image contrast by lighting up those black areas (as well as others). The lighter the room surfaces are the more light gets bounced back onto the screen and the worse the problems gets. Add to that a projector that has problems controlling internal light scatter, or inefficient polarization panels and that will add yet more light to the black areas (as well as others). Any ambient light (daylight or whatever) really adds problems with image contrast. The human eye gets much of it's critical information from contrast that is why deep blacks are more important to have in an image that bright whites.

You should go with a white screen and then only move to a gray screen if you are dissatisfied with the white one. That is why we almost always recommend that when someone is painting their screen they put a white primer on first and then watch that screen for awhile before going with a gray mix.

ambient light vs projected light are different how??? is light not just light? how do the react different???

thats my final qs

cheers for the help trying to get me to understand it all

Jase
Ambient light is almost always diffuse and unconcentrated and hitting the screen from a number of directions. Projector light is very directional and concentrated. Room light (ambient light) that hits the screen at the same angle as projected light will reflect exactly like the projected light (physics is physics), but ambient light hitting the screen at angles other than the projected light will not be reflected the same. It's all about the angles and the intensity of the light. You are correct, light is light, photons are photons, but the angles and intensities are different between most ambient light and the projected light. My apologies if I'm not explaining this well.
 

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Discussion Starter · #18 ·
sorry must reply.

For arguments sake. If the screen is a N7 grey and its reflectives make the picture we see be like a N8 due to the increased gain. Will the ambient light still only have a dulling washing out effect visually of N7.

this meaning N7 with gain additives will have blacker blacks and whiter whites or least more vivid contrast less dull than a N8 without additives to boost gain in the same given ambient light conditions.

Or is it simply not true the screen and paint manufactures etc claims of blacker blacks and whiter whites by having additives i.e. aditivies are not helping in that statement all.

To me if the aditives only make both blacks lighter and whites whiter with no advantage of less effect from ambient light by having the darker base grey one might as well just save the money and have a OTS paint or standard grey screen of a lighter N value if picture is to dark

word Jase
 

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sorry must reply.

For arguments sake. If the screen is a N7 grey and its reflectives make the picture we see be like a N8 due to the increased gain. Will the ambient light still only have a dulling washing out effect visually of N7.
Don't be sorry, no worries! :T

Correct, as long as the ambient light is not coming from the same direction at the projected light. Unfortunately I think I lost the photo in a computer crash, but I had a photo that was a number of different narrow screen test panels (1x4 feet) and in room light (overhead fluorescents) you could see a definite difference in shade between a BW™ panel and a N8 flat gray panel beside it; when I turned the room light off and projected a 100% white field (as bright a white image a the projector can go) it was very hard to tell the two panels apart. This was due to the intensity and directionality of the projected beam with no other lights on in the room (other than bounce-back) being present.

this meaning N7 with gain additives will have blacker blacks and whiter whites or least more vivid contrast less dull than a N8 without additives to boost gain in the same given ambient light conditions.
Almost. The reflectively enhanced N7 would have the SAME whites as a N8, but have blacker blacks if it appeared as an N8 under projection. Bear in mind that we are not talking about a day-and-night difference here. A visible difference, yes, but still relatively small.

Or is it simply not true the screen and paint manufactures etc claims of blacker blacks and whiter whites by having additives i.e. aditivies are not helping in that statement all.
This CAN be true, but only if the mix is darker than the reference screen and also has a higher gain than the reference screen. It also depends on whether they are talking performance against ambient light or performance under projection. A screen mix that I believe claims the above is Silver Fire. The almost-latest version of SF that we tested has a grayish color of around N7.3 while it has a peak gain of 0.91. This means it would have similar ambient light absorption as a N7.3 flat gray paint, but under projection, and on-axis, it would have the whites of a considerably lighter screen. The problem is that this mix has a relatively narrow viewing cone so people viewing from the sides of the screen will see a visibly darker image than those setting on-axis with the PJ.

To me if the aditives only make both blacks lighter and whites whiter with no advantage of less effect from ambient light by having the darker base grey one might as well just save the money and have a OTS paint or standard grey screen of a lighter N value if picture is to dark

word Jase
The reflective particles are added to a gray mix to boost it's gain over a flat paint the same shade without hot spotting (in our mixes). This does work. However, if there will be no ambient light present during viewing, and the projector will shoot a nice contrasty image that doesn't need any help with blacks, then the best screen to use in that situation is a pure flat white screen.
 

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Discussion Starter · #20 ·
cool that last lot was how I thought it worked. I got confused when it was said in an early part of one of my 2 forums/posts here that if the whites are brighter from the reflectives so are blacks............................

So in you opinion in ambient light and with light coloured walls would I notice a big difference between a Stewart 1.3 gain white screen and a Stewert 1.3 gain grey screen ( firehawk) from a centred seat position.

Just found this interested explanation but it doesnt mention that the grey screen actually absorbs light and that the grey will give blacker blacks as you said the pj cant stop all its light hitting the black area so a darker screen will look blacker. It just talks about the narrower viewing angle not having as much light bouncing back off the walls to fade the picture due to the way the layers make it up to 1.3 contrast. Also they say in a black cave they both look the same side by side where as the grey should still have blacker blacks? and greyer whites but have the same brightness http://www.integrityhometheater.com/the-stewart-firehawk-screen-how-it-works.html

I take it the firehawk will show better results in the scenario above than the greyhawk due to the increased gain.

lovin Jase

ps got resene space cote flat enamel base white today and blackboard black paint for the sides of wall and for a 1m deep semi circle for the ceiling hopefully that will help combat some of the ambient light bounce back as in review I linked then we are for a calibration.

still want to fully understand this stuff to see if it worth saving my Pennies for the material, firehawk or just a cheaper top quality white screen or a cheaper version of the greyhawk ( can get 140" for $125 US)

thanks again guys for all the help so far
 
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