Originally Posted by bud16415
No you can’t. A neutral gray screen works the same as a neutral density filter placed in front of the projector lens. It diminishes the total light output equally from end to end of the brightness scale. And in both cases it needs a projector brighter than the desired end result coming from the screen. You can’t dial up the white without dialing up the darks at the same time.
Of course when your talking about a basic neutral gray screen, or a neutral density filter, the above applies. But why is it when there is a thread...or discussion about advanced mixes do you always insist in describing scenarios that do NOT apply to advanced DIY screens? Just to be contrary? To "muddy" up the discussion...as it were?
I've said it before and it still applies...you have no personal reference or experience with the mixes under discussion, and as such your comments are at best limited to your personal speculations and opinions, based on your prior understanding of things along those specific and limited lines, and as such they are not definitative facts to be posted as "the end word" concerning advanced DIY Screen applications.
Now gain will add in the next level to what is going on by taking some of the light away from the side seating locations and directing it to the more central locations. I have read many times where some DIY screen paints claim to make the center seats brighter while not loosing any brightness at the extreme angle seats. That’s just not possible ether as a screen is a passive device and always acts equally to whatever light strikes it. It cant produce light on its own.
Where you misapply the point...having no reference as far as SF applications to go by....is that a properly configured and applied paint that contains metallic particles results in "more effective" reflection of the incoming light. Also, in as much as the dispersion and arrangement of those particles are not altogether uniformly aligned, the angle of the degrees of light reflection is more widely dispersed...much as is the same is to be said for a unity white surface.
Is the viewing cone reduction at 1/2 off axis of a higher gain SF mix the same as that of a white unity gain surface? No. And that has NEVER been claimed to be so...all though obviously it serves some to say as much to bolster some commentary. Can the difference be measured or ascertained by specific viewing of solid color fields and careful observation? Yes it can. Can the difference be noticed by those viewing from extreme off axis location? No such comments from any end user has related such. Therein lies the motivation behind previous comments that describe that there is no "viewing cone" issues with SF applications. Plainly stated, any differences are not noticeable enough to warrant any warnings to the opposite.
That aspect alone negates the validity of casting a blanket determination on the particular" mixes in question, and when the comments come from a source with no personal reference, the most that can be said of them is that they are personal opinions based on what personal knowledge and experience the commentator has....not what those who posses such screen observe in person.
A few other items not related to the above, but essential to make comment on before we see the posted results of any specific testing.
This is a big item in some people's minds, and used frequently to disclaim the quality of SF applications. But always...always it comes from observations made almost immediatly after the painting process. Even 1-2 hours after a screen dries it's much too early to make such definitive observations when the screen's composition consists of appreciable amounts of Poly. And it's been stated by many folks beyond the SF Developers circle that own SF Screens that after 1-2 weeks curing, NO Hot spotting is present.
I'm certain that even if I posted a Multi Question Poll intended specifically for SF users to weigh in on such matters that there would always be those who would disclaim the posted results. Such is simply the way of things I suppose...would that such be different though.
Another aspect of deceptive testing for supposed hot spotting is to use the "reverse negative" approach where a solid white or blue projected light is delivered to the Screen, then the image is reversed to become a "negative".
As a counter point, examples of screens that are of far less gain...all the way to being under 1.0 are the comparative examples used to determine such differences. Well, obviously a duller, less reflective screen will show less tendency toward hot spotting. That's a real "Duh" item...but when it's presented with a biased and somewhat deceptive wording, it can work to misinform people as to the reality of things specific to a much different application.
Simply put, a Camera's ability to gather subtile variables in light allows it to make such differences appear far more pronounced in a "negative" example. No human eye possesses such ability...or the sensitivity to ascertain such variances.
Also, as of now there are still no Projectors that posses completely uniform light dispersion to the edges of the perimeter of their light fields. Some are very close...but when even the best of such are viewed in the "negative", there is always a difference to be noted even on a reference white surface.
Based on previous examples shown to cases of "Hot Spotting" on SF screens, every screen has some degree of such.
Hot Spotting as truly understood in a real sense allows to the center of the projected image being noticeably brighter when viewed directly on axis...under normal viewing conditions.
Neutrality of Gray.
While it is true that in the past certain variations of SF did allude to the use of a mix that pushed ever so slightly into Blue, , and comments were made to the effect that such was intentional, the reason was because Blue...when introduced to a very slight degree, helped restore the appearance of brighter whites. At that time, a purely Neutral Gray without any additional elements added to counteract the resulting attenuation, always resulted in a dimming of whites into a noticeably grayer scale.
The introduction of a more translucent Neutral Gray mix, combined with more effective reflective components, serves to allow more accurate reflections of colors and whites. The Gray still enhances perceived contrast by darkening the light that is already "downwardly mobile", while the reflective elements within SF allow the brighter elements of the image to be reflected with far less attenuation than a pure neutral gray with or w/o Poly.
The popular comment about "Screen Passiveness" is often misused to the effect that it is claimed that by stating the above there is a claim that extra light is being produced. No such claim has ever been made....nor has it ever been alluded to in any manner.
What does happen though is the projected light is being utilized in more effective ways across many different aspects of the viewing experience. Much more light is being cast toward the sides that otherwise would be in most every other high gain screen application, reducing (...but not eliminating...) the degree of "off axis' reduction of foot lamberts. To that effect, to the "Eye" there exists no significant drop off of light off axis. Another aspect that helps is the translucency of the mix used and how the layers of such serve to produce a more effective "radiating" of the light being reflected by the reflective particles.
It cannot be helped if a few people are so entrenched on conventional thinking and past examples of lessor applications that they cannot accept such.....but in the end, it is those who actually attempt to make such screens...and their resulting observations that hold the most weight as far as convincing others as to the relevance and desirability of any such advanced DIY Screen application.