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'!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.
Harpmaker,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.
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.nice one thanks.
So what is the point to use anything but white?
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.Why would you use an N7.5 then try and make it upto N8 with reflective additives .why not just use N8
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.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.
Be careful of claims. Reputable companies will provide some proof (other than screen photos) of screen performance (usually gain charts).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??????????????????
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.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.
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.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???????
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.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 ).
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.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 )................................
You lost me here Jase. I don't know what you mean. :scratch: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?
Oh don't worry about driving me nuts, that happened a long time ago! :dumbcrazy: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 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.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
Don't be sorry, no worries! :Tsorry 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.
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.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.
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.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.
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.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