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Silver Fire vs. Scorpion - Tests Coming

post #1 of 60
Thread Starter 
So I was asked to start my own thread about SF2 vs. my existing 'wall' screen painted with Scorpion (50% C&S, 50% Black Widow). I have several sample on their way to me, and will try and perform some tests when I receive them.

I will probably paint some panels large enough to make a reasonable determination as to if it would be worth it for me to switch from my current screen to SF.

Thanks all!
post #2 of 60
Since you have started your own thread, can you give your PJ specs and maybe some macro pics of your scorpion screen?

I'm confused on who said what but can you post any screen shots?

Looking forward to seeing some side by side comparison
post #3 of 60
I for one am looking forward to the results, this site is awash with propaganda on paint mix results and these tests will hopefully show the true story.

I can then compare the facts of the SF paint mix to see how it really compares
in bright room conditiones to a Black Diamond screen which it was recently
pitted against but under bias conditions, seriously it was!!!

I know what the outcome will be but people need to see the facts for themselves.

Thanks for doing this.......
post #4 of 60
I have a jvc rs40 projector and I'm using scorpion diy paint as well ( for now ). I'm looking for a higher gain screen for active 3d. I would like to see if there's a difference also between the two. I have one screenshot here https://picasaweb.google.com/m/viewA...COez3uitwfLPCA of my 110" screen. Projector has not been calibrated yet.
post #5 of 60
I don't want to spoil your fun, but you may want to check the archives, there was a lot of very accurate testing done 3 and 4 years ago. I don't know if those mixes were tested or not but a very scientific process was put in place to compare A vs B fairly and show results in data along with meaningful photo comparisons. Some people disputed results as they always will but following these testing protocols will allow thinking people to fairly understand what it is you find. Just do your testing with disregard to the outcome and let the results speak for themselves.
post #6 of 60
Thread Starter 
Quote:
Originally Posted by bud16415 View Post
I don't want to spoil your fun, but you may want to check the archives, there was a lot of very accurate testing done 3 and 4 years ago. I don't know if those mixes were tested or not but a very scientific process was put in place to compare A vs B fairly and show results in data along with meaningful photo comparisons. Some people disputed results as they always will but following these testing protocols will allow thinking people to fairly understand what it is you find. Just do your testing with disregard to the outcome and let the results speak for themselves.
I have not been able to find them. If you find them let me know. Thanks!
post #7 of 60
Is there a list of 'accepted' screenshots or JPGs somewhere that people can use for such comparisons?

Over the years, I'm sure ( i hope) there is a standard set for apples to apples comparison.
post #8 of 60
Quote:
Originally Posted by ohcello View Post

I have not been able to find them. If you find them let me know. Thanks!

There are numerous threads that investigated many different paints and different concepts of what methods to use that were honest and scientific in nature.

One such link would be:
http://www.avsforum.com/avs-vb/showt...773&highlight=

If you do a search on threads started by the author of that thread you will find many more and links to stock images that can be downloaded and displayed as still images. The first step in comparing apples to apples. We took it past that and even left areas (windows) clear in the test image so the projector would display its best pure white light in those areas and a color sample could be affixed to the screen so there would be a known control in the photo. We didn't evaluate the photos totally by eye as each person's home monitor has a different calibration. But you can download color tools (eye dropper) that measure the image better. And in some cases members bought color and light measuring equipment to use at home to take direct readings. None of it was perfect but enough testing was done to convince most of us how the different screen paints DIY worked and the merits of each. Many DIY paints were around and worked excellent for many members. They fell out of favor as members grew tired of the forum. That's as deep as I will go into that topic.

Most of the investigation was into better ambient light performing screen surfaces, grays and grays modified to slight gains. My preference was always in searching for a surface that maxed out the potential of a given room and projector combination. I favored very bright projectors dark neutral gray screens and adjusting the surface sheen and texture to get a image devoid of any image artifacts (sparkles etc) My goal and some others was to produce a screen that wasn't there in your mind while viewing an image. We often called that an open window effect. There was lots of other work done on painting methods and screen construction, room design and color absorption etc.

One of my favorite threads was a early on one but laid the foundation for a lot of the thought process that followed.

http://www.avsforum.com/avs-vb/showt...810&highlight=
post #9 of 60
Thread Starter 
Quote:
Originally Posted by bud16415 View Post

There are numerous threads that investigated many different paints and different concepts of what methods to use that were honest and scientific in nature.

One such link would be:
http://www.avsforum.com/avs-vb/showt...773&highlight=

If you do a search on threads started by the author of that thread you will find many more and links to stock images that can be downloaded and displayed as still images. The first step in comparing apples to apples. We took it past that and even left areas (windows) clear in the test image so the projector would display its best pure white light in those areas and a color sample could be affixed to the screen so there would be a known control in the photo. We didn't evaluate the photos totally by eye as each person's home monitor has a different calibration. But you can download color tools (eye dropper) that measure the image better. And in some cases members bought color and light measuring equipment to use at home to take direct readings. None of it was perfect but enough testing was done to convince most of us how the different screen paints DIY worked and the merits of each. Many DIY paints were around and worked excellent for many members. They fell out of favor as members grew tired of the forum. That's as deep as I will go into that topic.

Most of the investigation was into better ambient light performing screen surfaces, grays and grays modified to slight gains. My preference was always in searching for a surface that maxed out the potential of a given room and projector combination. I favored very bright projectors dark neutral gray screens and adjusting the surface sheen and texture to get a image devoid of any image artifacts (sparkles etc) My goal and some others was to produce a screen that wasn't there in your mind while viewing an image. We often called that an open window effect. There was lots of other work done on painting methods and screen construction, room design and color absorption etc.

One of my favorite threads was a early on one but laid the foundation for a lot of the thought process that followed.

http://www.avsforum.com/avs-vb/showt...810&highlight=

Yeah I remember seeing this thread....very thorough tests of BW! I'm trying to find SF tests or Scorpion (50% BW, 50% C&S)..tests vs. white or vs. each other.
post #10 of 60
Thread Starter 
Quote:
Originally Posted by newB24 View Post

Since you have started your own thread, can you give your PJ specs and maybe some macro pics of your scorpion screen?

I'm confused on who said what but can you post any screen shots?

Looking forward to seeing some side by side comparison

I dont' have any photos yet, but I can tell you this so far:

ROOM:
Basement, finished, complete light control, 11 x 20, drywall. Screen is a painted wall at the end of this long and skinny room. Room is painted with very dark brown flat paint, and ceiling is very dark blue flat paint.

PROJECTOR:
JVC-RS10 Projector, Ceiling Mounted 12' from Wall, projecting a 115" diagonal image.

SCREEN/WALL:
Painted 4-6 coats (some trial and error : ) of primer, then 1-2 coats of flat white (forget brand, but smoothing paint designed to have less texture), then 3 coats of Scorpion Mix (with roller) (50% Black Widow, 50% Cream and Sugar). The paint was sent to me and I mixed it as directed.

Black Velvet Border around Screen/Wall

That's pretty much it. For the record, I'm not a big color accuracy guy.... if it's close to neutral, I'm usually pretty happy. I'm a very big contrast and black level fan, and I'm also very sensitive to sparklies or screen artifacts.

With this Scorpion mix, you occasionally pick up on one speck of the aluminum paint, but it's pretty rare and there is no frosty/sparkly effect other than that, which a very minor thing for me.

The screen performed very well, and does a decent job in ambient light...certainly better than matte white.

I tried Black Window straight up and it was just a little too muted for my tastes at 115" from the JVC..the whites looked 'dim' to my eye.
post #11 of 60
Quote:
Originally Posted by ohcello View Post

Yeah I remember seeing this thread....very thorough tests of BW! I'm trying to find SF tests or Scorpion (50% BW, 50% C&S)..tests vs. white or vs. each other.

Well there are a lot of things that could be called testing and no method that produces the best image for an individual in a specific room and with a given projector is a bad thing. What happens then is others read of a success story and try applying it to a different set of variables and of course will get a different outcome. The method I posted above didn't target the 50/50 mix you talked about but the procedure is valid for any comparisons.

The type of testing we wanted to get to was tests that explained how the screen surface was working and then we would know when it would be appropriate to advise someone to use that surface. Or to give us information to build on for even better results.

Some people always saw it as a competition of what is better, and there really isn't a better.
post #12 of 60
I don't get the "vs" threads. I though we are to calibrate the projector each time? Or is this where neutral mixes come into play.
post #13 of 60
Quote:
Originally Posted by hyperactiveme View Post

I don't get the "vs" threads. I though we are to calibrate the projector each time? Or is this where neutral mixes come into play.

You still need to calibrate for contrast and brightness, but the color shouldn't change if going from one neutral screen to another.
post #14 of 60
So that being said, really hard to do a side by side comparison. The best you could hope for is to say that both screen mixes are similar to eachother. Test them Individually and one could comment on specifics in regards to a particular mix.

Maybe a sticky of approved mixes for room types would be well served.
post #15 of 60
Quote:
Originally Posted by hyperactiveme View Post

I don't get the "vs" threads. I though we are to calibrate the projector each time? Or is this where neutral mixes come into play.

You are absolutely right. That's where comparisons like we see in the commercial screen forum, try and mislead people. They often demo a projector on a white screen and then drop a dark screen in front and everyone is wowed by the change in perceived contrast. There is benefits in ambient light with the dark screen but its not what the mismatch of calibrations reveals.

All things in a screen comparison consistent except the gray value and the CR will be the same just shifted down the scale. So the one properly calibrated for gray scale to the ambient level, equal losses on each end will look best with the highest CR. One of the reasons we always advised large test samples in doing A vs B and sometimes you have to do recalibrations. The reason for the control sample illuminated by pure projector light was also used to adjust for all this. That's pretty much why screen shots are useless when you see someone holding up their new paint mix sample in front of what they are trying to best and saying look seeing is believing.

A Simple neutral flat gray will preserve some CR with ambient light coming into the room. Add something to produce a mild surface sheen gain and it helps with ambient light coming from the sides by skipping that light off the screen and onto the other wall. Add darker walls and ceiling and floor nearest the screen and it helps with screen re-reflected ambient light. you can only go as dark as your projector has lumens to bring the image back up to par. As the ambient level in the room gets higher so does the amount of light you need coming off the screen because your eyes react to both the screen light and the room light. So each time the ambient goes up a point the projector has to go up two points. One for the attenuation the darker screen causes and one for the fact your eyes iris closes and needs more brightness.

All the other things added to screen paint metallic and texture work together for gain or dispersion and allow the viewing cone to shrink and thus a brighter image in the sweet spot. Anything that shrinks the viewing cone also helps with stray light from the side. Texture and metallic have both positive and negative to PQ. Things like sparkles etc are hard to see in screen shots so are things like relative brightness of a object moving across the screen thru the sweet spot.
post #16 of 60
I saw from the other forum you're in Long Island? If you're willing to have a guest from Queens make a drive out and check your setup out I'm game. I have all the components for the Silver fire (currently unmixed) as well as the graco 2900 sprayer. I'm very curious about this Scorpion screen and how it looks with my Epson 8350 on there. I also have a Epson 705HD.

I'm on vacation so I'm free for a month until St Paddy's. I'll PM my contact details if you'd like.
post #17 of 60
Regarding contrast ratio, if you don't readjust, sure, the ratio is the same.

But, if shooting onto gray, it brings the black level down (deeper black), can't you then boost white level to get closer to white again.. thus increasing the CR?
post #18 of 60
Quote:
Originally Posted by SonyCrusader View Post

Regarding contrast ratio, if you don't readjust, sure, the ratio is the same.

But, if shooting onto gray, it brings the black level down (deeper black), can't you then boost white level to get closer to white again.. thus increasing the CR?

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. The difference in the two methods of reducing brightness is with doing it at the screen it also lowers reflected ambient light thus maintaining a bit more of the projectors native CR the cost for the improvement is it takes more lumens to get the same brightness from the screen as a white screen would produce. That's the true CR change.

There is also perceived contrast, or how our eyes perceive black with regard to what is bright in the image. Similar to what we see in an ANSI test pattern. I believe darker screens allow for overdriving the light output some beyond what is needed to overcome the losses of a gray surface when faced with ambient issues. The benefits of a brighter image in a brighter room is that our eyes correct and we increase our perception of contrast in mixed ANSI type images.

That would be comparing two screens of equal dispersion. 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.
post #19 of 60
Thread Starter 
Quote:
Originally Posted by cbtk View Post

I saw from the other forum you're in Long Island? If you're willing to have a guest from Queens make a drive out and check your setup out I'm game. I have all the components for the Silver fire (currently unmixed) as well as the graco 2900 sprayer. I'm very curious about this Scorpion screen and how it looks with my Epson 8350 on there. I also have a Epson 705HD.

I'm on vacation so I'm free for a month until St Paddy's. I'll PM my contact details if you'd like.

Thanks so much, but it's doubtful... hard for me to get away. Again thanks for the offer.
post #20 of 60
Quote:
Originally Posted by ohcello View Post

Thanks so much, but it's doubtful... hard for me to get away. Again thanks for the offer.

Huh??????
post #21 of 60
Quote:
Originally Posted by ohcello View Post

Thanks so much, but it's doubtful... hard for me to get away. Again thanks for the offer.

I think you missed the point, he wants to see YOUR scorpion screen and he has a whole month to work around your schedule.
post #22 of 60
Quote:
Originally Posted by bud16415 View Post

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.

Quote:


per bud16415:
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.

Hot Spotting:

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.
post #23 of 60
Quote:
Originally Posted by MississippiMan View Post

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.

Very good to know.
post #24 of 60
Quote:
Originally Posted by MississippiMan View Post

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.



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.

Hot Spotting:

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.

The post I replied to asked specifically about CR and expanding it on a GRAY screen. By allowing the gray to produce a darker black image while adjusting the upper end brightness improving CR. Not only is that not possible it goes contrary to the laws of physics. And those same laws govern all painted surfaces flat gray paint or metallic improved gray paint. Simply put whatever is in the paint that reflects light from the projector no matter how the pigments are aligned will act on a very dim beam of light the same way it works on a very bright beam of light. That is what referring to a screen as a passive reflective surface is. There are no passive pigments that can absorb dim light while intensifying bright light.

I wasn't posting to undermine any ones advanced screen paint formula. I was participating in a discussion forum giving reference to useful threads that others can read and expand their own knowledge and draw their own conclusions, as last I checked we still live in a free country where a person is allowed to have an opinion and freely state it. One persons desire for a statement to not be true does not make the others statement false. If you want to post a rational scientific explanation of how a screen can differentiate between light brightness and act on reflecting it back to the viewer in different ratios, I would love to read it and comment and if you truly have produced a active screen surface as opposed to a passive screen surface I will personally applaud the effort and even support your nomination for a Nobel prize in physics.

For those new to the forum and the OP please excuse the off topic elements to my post. This may however shed some light why the collaborative experimentation here no longer takes place and why the threads I referenced as to proper testing methods haven't been revisited in 3 or more years.

This is truly a great topic to discuss and gaining a general understanding of all the interactions between projector, screen, room and human will help everyone interested in building a home screening room do so to the best of their abilities.

I have felt for several years I have not been welcome to post here. I thought that may have changed but I guess not.
post #25 of 60
On the topic of hot spotting. The nature of any method of projection thru arrays of lenses where the light is emitted out of the projector thru a small opening and travels outward in two dimensions diminishing in strength as it goes and striking a flat surface (screen) there will be a brighter central image. Much has been done thru optics and electronics to make correction but as MM rightly posted above there is always some degree of greater center brightness that slowly transitions to the edges and corners. That is not necessarily a hot spot situation. The human eye like a projector has an iris and lens and a receiving device in the optic nerves. It also has limitations in its peripheral vision abilities, and it is connected to a super computer (brain) that adjusts that image in many ways to produce vision. It is not until a discernable threshold is reached based around the screen surface the projector and the projector placement relative to the eyes viewing it should it be called hot spotting many screens will show a hot spot if the viewer were to get down very low to the floor and look up at the screen but would show none from a normal seating location. Think or the ultimate high gain screen being a mirror and positioning yourself so that the projector beam hit the screen at some angle and then your eyes were the opposite angle to the screen such the blast hit your eyes. The exact opposite would be a rough surface painted flat white that did a perfect job of scattering the light 180 degrees. there still would be the warm area but well within what our eyes would correct for. All these directional gain screen surfaces are at some point between the two extremes.

The method of photographing a screen and the reversing the image (negative) was not invented to disparage one screen over another it was only done to illustrate something that's hard to see by eye so valid comparisons can be made. No one ever said warm spotting is bad. Whenever any method was derived to explain anything, it was always viewed as a conspiracy to disparage just one persons accomplishments even though all solutions were subjected to the same scrutiny. Being able to understand things is and be able to make predictions is good. There is nothing wrong with using your eyes and saying that's a great looking image. It's like going to the doctor and having him say wow you look great now lets take your blood pressure and you say no way you just told me I was as good as I could ever be you are just looking for something wrong.

Another test we used to like to do was take a photo of a screen with a flash with the projector off. the flash being intensely bright and very much inline with the lens and or eye, would exaggerate the ability of the surface to hot spot. Everyone knew it wasn't a real life situation just a method of comparing A to B to gain information on different screens.

Many things go into a great front projection viewing experience. Contrast ratio, brightness, are all very important. Over the years some of us talked about less measurable attributes to image quality things like motion on the screen and how motion can remind us of the screen being a flat surface where in a still image that's not apparent. The eye brain interface is very perceptive of slight changes with movement and changes in brightness across the screen sometimes can spoil a 3D illusion so can uneven texture etc.
post #26 of 60
Quote:
Originally Posted by MississippiMan View Post

Hot Spotting:

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.

You might need to change this statement to more than 1 week. After 1 week of curing, I can still see hot spotting.

Quote:
Originally Posted by MississippiMan View Post

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".

My experience has been only 1 week, so I will update my results after 2 and 3 weeks. I am not trying to start a war of words here, but simply stating that I can see the hot spotting using regular content. My experience is not based on such tests, but was noticed from a picture slideshow where the pictures have a thick white border around them. You can clearly see that the white border in the middle of the screen is brighter than the white boarder on the side 1/3 of the screen. I do not see this behavior from another gray screen or my matte white screen.

Quote:
Originally Posted by MississippiMan View Post

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.

Yes, but in the case of commercial applications, they are often using micro lenses to redirect the light toward the viewer rather than allowing it to redirect it toward the wall. In this case, these screens have a very narrow viewing angle, often only 30 or 40 degrees. It has been said that SF has a very wide viewing angle, and my person experience supports that. In order to accomplish this it would have to allow the light to be diffused on the screen and reflect the light outwardly as well as toward the viewer, so it would not be able to brighten the center of the screen the way a commercial high gain screen could.

Quote:
Originally Posted by MississippiMan View Post

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.

I am sorry, but this statement bugs me. A human eye possesses more dynamic range than any camera that doesn't use multiple photos at different exposures to increase the DR of the photograph. Are you suggesting that a camera can capture more detail and subtleties than the human eye? If so, then we wouldn't be able to see them in the photograph either.

Quote:
Originally Posted by MississippiMan View Post

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.

I completely agree, and any test that is done should be done with a reference image using a completely flat screen with no gain or negative gain. That way people can see how much uniformity the projector has before determining the amount of hot spotting a screen may possess in a test.

Quote:
Originally Posted by MississippiMan View Post

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.

Just for the sake of being clear here, the reflective elements in SF are also brightening the blacks. The reflective elements can't actively reject some light and not others.

Quote:
Originally Posted by MississippiMan View Post

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.

I don't know who the "few" are, but for the record I am only interested in visible and measurable qualities in a screen. I don't really care about what he said she said stuff happened before nor do I care to be a part of that now. All of my comments are either based on what I am able to see with my projector and the screens I have on hand, or what science has proven to be true.

BTW, I hope this doesn't come across as an attack on MM or SF, because it is not. I am just trying to provide an objective opinion on a few things.
post #27 of 60
Quote:
Originally Posted by brianjb View Post

You might need to change this statement to more than 1 week. After 1 week of curing, I can still see hot spotting.

I've not used SF V2, But My SF 2.0 V1 screen took about 3 weeks of curing to get rid of the hot spotting. So hang in there!

The only problem with my screen is a slight graininess due to mis application. (I've got some "Orange Peel".) I have NO sparklies, hot spotting or anything like that. Off Axis viewing is excellent. Ambient light performance is excellent. Dark room performance is simply outstanding. (Epson 8700UB and 144" SF 2.0 V1 screen.) I am VERY happy with my screen. And I don't have a horse in this race. I'm going to redo my screen because of some problems, my fault, and I am definitely going to use SF again. I'm not saying anything bad about any other mix, I have no experience with those. But I have nothing but good things to say about SF.
post #28 of 60
brianjb;

You might need to change this statement to more than 1 week. After 1 week of curing, I can still see hot spotting.

let's be clear that what you have is a sample made from someone else at another forum with an agenda to steer you in their direction. having said that, i don't know whether they made an honest attempt to correctly make the sample... so let's assume (glass half full) that they did try to do that.

now with regard to hot spotting... i do not know the make/model of your PJ or it's uniformity... but i'll assume your setup is currently calibrated to your larger (or full) white screen... as it would be very hard to calibrate it the other way around. therefore, the best you could really say is that the gain of the 1week uncured SF fire sample you have, is enough that improperly calibrated it could hotspot. on a side note, we've always said that it takes at the very least 3 weeks to begin to cure. i have made hundreds of 2' x 2' samples over the years and i do not pretend for one moment to know how it would scale to a large full screen. there are clues, yes, but nothing concrete. i've had those moments for sure when the sample at hand "dusted" yes kicked the butt of everything large scale i could throw at it... only to be sorely disappointed when using the exact same mix i made the sample from... into a full screen. it's happened over and over again.

Just for the sake of being clear here, the reflective elements in SF are also brightening the blacks. The reflective elements can't actively reject some light and not others.

yes and no. mica is an array of the full color spectrum... it both aborbs light and reflects it. the 'base' of silver metallic paints contains lamp black which absorbs color (usually detrimentally - loss of detail) while it coats the mica that reflects light exceedingly too well (also usually detrimentally - loss of detail from hotspotting). it is a marriage that leads us to find a 'screen' that is to our individual likings. just remember, a PJ does not project black, therefore the darkest black will be your screen color itself... all other black levels are perceived. SF does a better job of reflecting what is projected (that includes the incremental minute amounts of projected light that make up the black level grey scale) back to the viewer... therefore, it does often appear that the blacks on SF are lighter. there are of course other factors... and they usually center around your PJ's contrast and it's ability to prevent light leakage...

i do see other non facts and inconsistencies littered throughout this entire thread... but for now... i will hold me peace.
post #29 of 60
Quote:
Originally Posted by pb_maxxx View Post

let's be clear that what you have is a sample made from someone else at another forum with an agenda to steer you in their direction. having said that, i don't know whether they made an honest attempt to correctly make the sample... so let's assume (glass half full) that they did try to do that.

Where did you get that from? Clearly you are making an assumption here. Please understand that I have no agenda here. I did not make any of these paints, so I simply don't care what performs good and what performs bad. I am glad to see that you are taking the "glass half full" approach, but in a way it almost seems tongue-in-cheek.

Now with that out of the way, I decided to mix my own while I was waiting to receive a sample from someone on another forum. I knew this would be brought up, and like I said before I don't want to be any part of the controversy. I mixed some BW, I mixed some SF3 v2, and I have Elite white and gray screens. I may even mix some Scorpion or Elektra N8. Fortunately the panel I received and the screen I painted look the same so far. Whatever conspiracy theory you think is going on hasn't involved me.

Quote:
Originally Posted by pb_maxxx View Post

now with regard to hot spotting... i do not know that make/model of your PJ or it's uniformity... but i'll assume your setup is currently calibrated to your larger (or full) white screen... as it would very hard to calibrate it the other way around. therefore, the best you could really say is that the gain of the 1week uncured SF fire sample has enough that improperly calibrated it could lhotspot.

I have an Epson 8350, and I calibrated my projector to each of the four different screen types, and stored them as presets.

Quote:
Originally Posted by pb_maxxx View Post

on a side note, we've always said that it takes at the very least 3 weeks to begin to cure.

I am not sure who we is, but I see you and MM as the primary authorities on SF and he just said 1-2 weeks. I have no problems waiting another 2-3 weeks to see how things play out, but it doesn't look good when the answers change. It brings on the perception that someone is providing answers that are convenient to the situation, but I will write it off to a mistake or oversight and move on and assume 3 weeks is the right answer.
post #30 of 60
brianjb,

i really dont see someone spending $60-75 on artists paints to make just a sample... but if you did... then all the power to you. as for your other sample, i'm well aware of who sent it to you. as for being able to properly calibrate to a small sample... i'll assume you came relatively close. samples are just that, an incomplete picture of the whole picture.

i won't assume anymore on the sample you received. but i have read and correct me if i'm wrong but you rolled your sample. and given that you did so in a 'wet' coat... the application issues of rolling immediately jump out at hand. and the placement of the sample (orientation) during testing would certainly have a effect of the visual outcome. and yes, i highly doubt that do to the application of your sample, that it will ever not hotspot.

as for curing time... i can't think of any who has ever said only 1 week... including MM... so no, the answers have not changed in that regard.
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