The Perfect Silverscreen?

[RAGEdemon]

I stumbled across a website for a company that sells a special kind of screen with 10x gain and even 20x gain. Yep you read the right.

These screens are apparently sprinkled with aluminium so I am wondering if these would make an excellent silverscreen.

Brightness is always an issue with projectors, but especially so when it comes to stereo as with a polarisation or shutter glasses setup, as there is only 24% of light that gets through.

These high gain screens would go far beyond just fixing the light output.

The url is:

http://electricimagetech.com

[Jahun]

Hmm...

I wonder if anyone has experience with them, but with gains like that they sure get close to being pure mirrors. I suppose there is a reason why they either bend the screen a tad cylindrical in the 20x version, and make the widescreen version half the gain, being 10x. (" Equal image quality from the center to the edge due to precision parabolic surface")

And that bending will give problems I think, since you use a normal beamerlense. So the image will get out of focus at the borders.
Either you have to sit a long distance away, or you'll most probably see hotspotting too..

If you only use the screen alone and can sit far away, that is fine I guess. But then again, you'd see an effectively smaller screen

[DDuckMan]

20x. I don't think I have seen a gain that high before.

Don't forget that as the gain increases, there are increasing problems with narrow field of view, hot spotting (uneven light distribution), black level reproduction, and color shifting. Most consider 1.2 gain to be about the max gain for an acceptable HT experience. A few will go up to 2x gain to get a large screen with acceptable brightnes, but those screens typically have viewing angles of only 25 degrees.

To get to 20x, or even their 10x screen, the parabolic shape must be severe enough to double as a satellite dish. Even for gaming use, I doubt those screens would have an acceptable image quality. The Dupic screen they have is flat and according to them, has 5x gain and a "360 degree" viewing angle. That one sounds interesting, but I would look for an independant review before ordering one. If you decide to try one, let us know how it works out.

[RAGEdemon]

That is interesting... those are the first things I thought too, but upon further research...

For the 10x screen which I think is optimum

1) the curvature is hardly noticeable and is only horizontal just like large cinema screens, as seen on here:

http://electricimagetech.com/superbrightscreens/

>>> "Products" at the top

>>> in "Screen Selection Guide & Comparison"

2) the viewing angle is actually 40+ degrees, and it stabalises to flatness at the edges so quite possibly 135 degrees plus as seen from here:

http://electricimagetech.com/superbrightscreens/

>>> "Products" at the top

>>> in "10 X Screens (10 gain, Wide Viewing Angle)"

Although as expected, there is a small hotspot in the center.

I expect these would be quite expensive, but if you can afford a dual projector setup then this might be within reach as a "silverscreen" if it can be used as such

Personally I have a 2.5 gain glass bead screen, and with 2500 lumens, it serves me well even with shutterglasses.

Quite correctly, consulting an independent review would be advisable, but no place on the net even mentions this website. Looks like a new upstart.

[Jahun]

It just can't be imho.

Let's assume you take any projector and put it on a perfect white/diffuse wall. (I suppose like 1.0 gain sort of normal screen would do). Light is diffusively scattered in all directions. I don't believe a white screen would actually absorb any measurable amount of light either...

Now when moving to silver screens, you progressively go towards a mirror. Gain right in front of the screen goes up drastically, but viewing angles must go down just as fast. There is only a certain amount of light to spend, if 10x more light reaches you, I'd say the original cone should drop by something like 10 too..

Stewart screens or Silverfabric's data sheets make sense, they did their best and created a sort of small plateau around small viewing angles, behind that, it just drops dead on the floor. Because all the light that was originally there on a normal screen, is focussed now.

Unless anyone can find a review, I don't trust it at all..


ps: I think even slight curvatures show loss of focus quickly..
pps: it is not new at all.. http://www.hometheaterforum.com/htf/sho ... 566&page=2

Already referred to it in 2003.

Odd that no one ever talked about it again on the net

[DDuckMan]

I agree. Their datasheets look promising, but I have yet to see a high gain screen that doesn't trade some image quality or usable viewing area to get the light back to you. Stewart and some of the other big companies are pretty honest about it, so you have a good idea what you are getting. This site conspicuously lacks information about drawbacks.

On the other hand, I don't have any experience with projected gaming (yet). Perhaps it is more forgiving of high gain screens. If you like your 2x screen, one of theirs may be better. Too bad Neil does not want to review hardware.

Head over to the screen section of the AVSforum and ask them about it if you can't find a review.

One additional note. On their chart of gain vs. viewing angle, they are showing how much gain you can expect at different viewing angles, ie seating positions. I don't believe that necessarily translates into a "hot spot" on the screen, which indicates uneven reflection of light to a single sitting position.

Edit: Here is a thread you may find interesting:
http://www.avsforum.com/avs-vb/showthre ... =high+gain

[Jahun]

True DDuckMan, their chart shows seating positions, I believe that usually correlates to hotspots pretty well. In this case with a curved screen that doesnt't need to be the case. One person can have a homogenous screen I suppose and have a 20x gain.

But then you have something like a curved mirror lense thing. Mirror is bad already, making it curved should produce an even worse viewing angle chart. (it is just a lense!)

What I think they are doing:
They mapped out the response of the screen on angles. So if I put a person on say 70 degrees angle, and the projector on -70 degree angle, yes you will have still a top gain! And yes normal screens would have sucky gain. But that is quite an absurd way of showing it.

edit: good find on the review, that person did more of those and does them nicely. His numbers all make sense to me.

[sharky]

hi guys.. i tested different materials because i wnated to make my own silverscreen at home... i tested them with a LED bighind a filter and watched through another filter.. on depolarizing materials i could see perfectly the light of the led. on non depolarizing i couldn't see it. i found out the SANDED steel or aluminim plates do not depolarize the light.. aluminium works best... just need a sanded one without scratches... you can get a 2x3 meter plate for around 50euro (60$) MUCH less then the 5000 dollars of a same size pannel ai saw on a site... i think it worth a try... if it is fine sanded you will have a nearly perfect image without ghosting...

in case let me know..

bye

[Jahun]

Let us know how it works out Sharky!

However, I am absolutely sure you will not get a ghost free image... just is not possible. Either that, or it works too much as a mirror, and you will see major hotspotting. The back of aluminium foil for instance looks a bit like sanded aluminium, and it still ghosts a bit and is way too reflective.

That said, I'd think it would be possible to get near to the quality of commercial screens one diy way or the other..

Sanding aluminium seems to me to be at least as viable an option as spraying alu paint.. so I am very interested to hear your results!