Can I use a High Gain screen but still keep my PJ as a ceiling mount? - AVS Forum
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post #1 of 10 Old 10-04-2013, 08:05 PM - Thread Starter
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I want to use a high gain screen for 3D only to make up some of the light losses. I know mounting the PJ high is not ideal but what will I loose by keeping the PJ at the height of the top of the screen and say using a HP 2.4 or 2.8.

I already have a 2.35:1, 120" diagonal Screen Innovations solar 4K which is actually measured to be 1.37 gain. 2D is fine, 3 D a little dim for me and that is running 3D on a a 16:9 @ 95" diagonal .

I just figured if I bought a second screen to drop for 3D only maybe I would gain back some of the light lost using the glasses. If I have to drop the PJ too that will be a bit of an issue.
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post #2 of 10 Old 10-05-2013, 05:47 AM
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The 2.8 HP is no longer made, you can only get them in the used market.
You will gain another screen that is no brighter than the screen you have. Max gain is with the projector placed so your audiences eyes are within 12-14 inches of the lens height. People will tell you to use the calculator to see what gain you will get but if you don't plan on doing it correctly don't do it. I own the 2.8 and have had the 2.4in my home for a week and if you fail to follow the rules of physics you won't get the results you are looking for.

This is the type of placement I am talking about for best gain. Better yet would be to have the projector farther behind and up just over my head height to widen the max viewing cone. This setup works fine for the 3 chairs but my center chair is the cats meWOW The light is being reflected directly back to the lens so you need to be in that path.

IMG_0560.JPG

Here is what a 2.8 gain looks like when you take a flash picture and you are getting full gain.
100_1832.JPG

Here is what the same screen looks like with no flash
IMG_0561web.jpg
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post #3 of 10 Old 10-05-2013, 08:25 AM - Thread Starter
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Quote:
Originally Posted by airscapes View Post

The 2.8 HP is no longer made, you can only get them in the used market.
You will gain another screen that is no brighter than the screen you have. Max gain is with the projector placed so your audiences eyes are within 12-14 inches of the lens height. People will tell you to use the calculator to see what gain you will get but if you don't plan on doing it correctly don't do it. I own the 2.8 and have had the 2.4in my home for a week and if you fail to follow the rules of physics you won't get the results you are looking for.

This is the type of placement I am talking about for best gain. Better yet would be to have the projector farther behind and up just over my head height to widen the max viewing cone. This setup works fine for the 3 chairs but my center chair is the cats meWOW The light is being reflected directly back to the lens so you need to be in that path.

IMG_0560.JPG

Here is what a 2.8 gain looks like when you take a flash picture and you are getting full gain.
100_1832.JPG

Here is what the same screen looks like with no flash
IMG_0561web.jpg

I cannot do this position with my PJ so I guess you answered my question perfectly and I expect this answer to be honest.
I'd say the best I can do is stack a second PJ to get the extra brightness, even then I'd say not practical for anything except 3 D.
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post #4 of 10 Old 10-05-2013, 08:42 AM
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Quote:
Originally Posted by roxiedog13 View Post

I cannot do this position with my PJ so I guess you answered my question perfectly and I expect this answer to be honest.
I'd say the best I can do is stack a second PJ to get the extra brightness, even then I'd say not practical for anything except 3 D.

Can you get a drop extension for the projector?
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post #5 of 10 Old 10-05-2013, 11:15 AM - Thread Starter
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Originally Posted by nickoakdl View Post

Can you get a drop extension for the projector?

Yea, I could put a drop extension, would still be only about 1/3 the way down the screen I believe. If I do this I would install two things.
One would be a electric drop for the PJ, the second would be a electric drop High Gain screen but would have to keep the height a little
higher than my fixed wall screen so that I keep the screen closer to the straight line of the PJ and thus maximize the benefit of the 2.4 gain
screen .
This would give me the best for both 2D and much improved situation for better for 3D . Actually, I could probably make one more change
and that would be to move the high gain screen position about one foot closer to the PJ, which would be closer to the viewers as well. This
will also help to improve the reflected brightness and at the same time create a bigger field of view for the audience.
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post #6 of 10 Old 10-05-2013, 11:41 AM
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Quote:
Originally Posted by roxiedog13 View Post

Yea, I could put a drop extension, would still be only about 1/3 the way down the screen I believe. If I do this I would install two things.
One would be a electric drop for the PJ, the second would be a electric drop High Gain screen but would have to keep the height a little
higher than my fixed wall screen so that I keep the screen closer to the straight line of the PJ and thus maximize the benefit of the 2.4 gain
screen .

This would give me the best for both 2D and much improved situation for better for 3D . Actually, I could probably make one more change
and that would be to move the high gain screen position about one foot closer to the PJ, which would be closer to the viewers as well. This
will also help to improve the reflected brightness and at the same time create a bigger field of view for the audience.

Having the projector and the screen line up is not the goal. The goal is to have your projector and eyes line up.. If you did what you said, you would need to stand under the projector to get the gain.. you want the gain where your eyes are when sitting .. Hope that makes sense.
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post #7 of 10 Old 10-05-2013, 01:18 PM - Thread Starter
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Quote:
Originally Posted by airscapes View Post

Having the projector and the screen line up is not the goal. The goal is to have your projector and eyes line up.. If you did what you said, you would need to stand under the projector to get the gain.. you want the gain where your eyes are when sitting .. Hope that makes sense.

Yes, makes sense. What you are saying is that I need to keep the PJ on the ceiling and raise the seats 4 feet biggrin.gifbiggrin.gifbiggrin.gifbiggrin.gifbiggrin.gifwink.gif

I had another look at my setup and really, the best I can do is have the PJ one third the way down from the top of my screen, my first row seating puts ones eyes at about one third the height of the screen ( the recommended height) and the second row about half way up the screen.
Cannot see how the two ( eye height and PJ center) can line up anyway unless the center row of seats is out, otherwise you would be projecting partially on the back of the seat.
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post #8 of 10 Old 10-06-2013, 05:40 AM
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Have you tried covering up that mirror?!
It seems like right behind the projector on a high gain screen would destroy contrast.
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post #9 of 10 Old 10-06-2013, 06:47 AM
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Quote:
Originally Posted by rcohen View Post

Have you tried covering up that mirror?!
It seems like right behind the projector on a high gain screen would destroy contrast.

Yes, the mirror gets covered every night. I use a black twin sheet with these cloth picture hooks sewn across the top and sides to attach it.
http://www.dickblick.com/products/cloth-picture-hangers/
I hang 4 velvet panels on each side of the screen (magnets), cover the picture and DVD cabinet with black fabric as well as the mirror.

One thing to note, the mirror does not seem to effect the image as much as you would think.. There are times I forget to put it on and never even notice. The wall and ceiling that makes a huge difference.
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post #10 of 10 Old 10-07-2013, 06:36 AM
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Interesting. At our office, we have a big HP screen, and stray light at the back of the room has an exaggerated effect. Perhaps it's the difference between ansi and on/off contrast, since your light would be timed with bright images. On the flip side, stray light off axis has a reduced effect. No surprise that diffuse light near the screen is bad, though.
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