# Projector Help, large screen short throw



## gafftaper (Dec 2, 2014)

Thanks to @LavaASU I have a fantastic used rear projection screen donated to my school. The screen is 18' High by 32' wide. Once mounted on a frame and flown, it will reach down to about a foot off the deck. The ideal location for me to hang it on stage is just behind my mid traveler, 14 feet from the rear wall of my theater. Yeah, that's a really short throw for a 32 foot wide screen. 

Assuming there is no projector out there which I can use in that short of a throw, what can I do? 

The only idea I have is to mount a projector off to the side of the stage on the back wall aim it toward center then mount a first surface mirror at center and shoot sideways into the mirror. I could have some sort of hinged mount created for the mirror so that it is easy to swing out and locks into the perfect position. When the rear cyc is flown in I have about 2 1/2 feet between the cyc and the rear wall. So there should be enough clearance for a rig to be installed permanently.

Ideas?


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## BillESC (Dec 2, 2014)

How about a hole in your back wall 

Even BenQ's PU9730 with the ultra wide lens would require 22'4" to fill your screen.


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## robartsd (Dec 2, 2014)

gafftaper said:


> Thanks to @LavaASU I have a fantastic used rear projection screen donated to my school. The screen is 18' High by 32' wide. Once mounted on a frame and flown, it will reach down to about a foot off the deck. The ideal location for me to hang it on stage is just behind my mid traveler, 14 feet from the rear wall of my theater. Yeah, that's a really short throw for a 32 foot wide screen.
> 
> Assuming there is no projector out there which I can use in that short of a throw, what can I do?
> 
> ...


The first surface mirror would have to be quite large - I think you'd be better off working towards a multiple projector setup or being satisfied with a projected image that doesn't fill the screen (at least the traveler can frame the width).


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## sk8rsdad (Dec 2, 2014)

Panasonic, and likely others, make some large venue projectors with wide angle lens options that can fill the screen. It calls for a 0.38:1 lens which is the widest angle available in that product line.

http://panasonic.net/avc/projector/calculator/html/aspct169/dz870_030_1610.html


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## gafftaper (Dec 2, 2014)

sk8rsdad said:


> Panasonic, and likely others, make some large venue projectors with wide angle lens options that can fill the screen. It calls for a 0.38:1 lens which is the widest angle available in that product line. http://panasonic.net/avc/projector/calculator/html/aspct169/dz870_030_1610.html



Well that definitely meets my distance from the screen to the back wall restriction. However that lens cheats the throw distance with some extreme keystoning. In order to be placed 12' from the screen it has to be 8' above/below the edge of the screen. Since my screen would end up 1' off the deck, I would have to mount the projector upside down on the back wall 26'+ above the deck... with two electrics, cyc, boarders, etc in the way between that position and the screen, there's no way I can create a clear path for the light from the projector to hit the screen from that position.


BillESC said:


> How about a hole in your back wall


I have seriously considered that. However the back wall has a lot of pipe and duct work and the other side of that wall is a hallway which is both the stage left/right crossover and the way in and out of the green room. So I would be creating a huge backstage noise issue.


robartsd said:


> The first surface mirror would have to be quite large - I think you'd be better off working towards a multiple projector setup or being satisfied with a projected image that doesn't fill the screen (at least the traveler can frame the width).


Yeah I'm thinking a multiple projector setup, combined with masking the screen a little smaller is probably the way to go.


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## LavaASU (Dec 2, 2014)

I'd suggest multiple projectors. On the upside you/your kids get to learn blending .


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## Footer (Dec 2, 2014)

Before you go down the multiple projector rabit hole... what is your realistic budget here? What gear do you have already? A switcher that can do edge blending can easily cost as much as a properly sized projector. Also, for a screen that size you are looking at a minimum of a 15k projector... not cheap. Are you married to this screen size? Sounds like you got a free screen that is way to large for what you might need?


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## AudJ (Dec 2, 2014)

As a side, we tested an ultra short throw projector recently. I was hoping to have the ability to move the screen to different lines, as well as avoid shadows if used with actors. There is no good place to project from in our room, as the back wall is blocked with a shell, and the house goes back over 150 ft., requiring an expensive lens. The projector we tested could only get us to about 15 feet wide before we started to see problems. Not quite bright enough yet either. Watching the technology however, as it would be nice to have the projector less than 4 feet from the screen and out if sight.


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## gafftaper (Dec 3, 2014)

Footer said:


> Before you go down the multiple projector rabit hole... what is your realistic budget here? What gear do you have already? A switcher that can do edge blending can easily cost as much as a properly sized projector. Also, for a screen that size you are looking at a minimum of a 15k projector... not cheap. Are you married to this screen size? Sounds like you got a free screen that is way to large for what you might need?


I'm in an unusual situation as I will have money to support this project eventually. At the end of the year about 2/3 of the rental money my theater makes gets deposited into my capital improvement/maintenance budget, and I get rented out a lot. Since I have a nearly brand new building I don't need to do any major maintenance or be saving up for new draperies and things like that, so I can afford to spend my money on cool improvements. Depending on how expensive this is it may mean I have to save up for a couple years to complete it, but I imagine I can probably afford to do this in the next 2-3 years.

Am I married to the screen size? Yes and no. If shrinking the screen size down 10% will mean a significant savings (or simply make it physically possible) then I'm willing to do that. But on the other hand if I'm doing this, I'm going to do it right. If that means I have to choose between doing this in 2 years and getting for a 25' wide image or waiting 3 years to get the full 38' wide image, I'm okay with waiting. Fortunately every year i have to wait to do this means that the technology gets cheaper. So that's not a bad thing either.


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## LavaASU (Dec 3, 2014)

gafftaper said:


> I'm in an unusual situation as I will have money to support this project eventually. At the end of the year about 2/3 of the rental money my theater makes gets deposited into my capital improvement/maintenance budget, and I get rented out a lot. Since I have a nearly brand new building I don't need to do any major maintenance or be saving up for new draperies and things like that, so I can afford to spend my money on cool improvements. Depending on how expensive this is it may mean I have to save up for a couple years to complete it, but I imagine I can probably afford to do this in the next 2-3 years.
> 
> Am I married to the screen size? Yes and no. If shrinking the screen size down 10% will mean a significant savings (or simply make it physically possible) then I'm willing to do that. But on the other hand if I'm doing this, I'm going to do it right. If that means I have to choose between doing this in 2 years and getting for a 25' wide image or waiting 3 years to get the full 38' wide image, I'm okay with waiting. Fortunately every year i have to wait to do this means that the technology gets cheaper. So that's not a bad thing either.



Also, look at projectors with built in edge blending. That would save a lot of $. I know the larger Christies and Barcos do it, I'm not sure which smaller units do.

Are you allowed to buy used or B stock?


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## gafftaper (Dec 3, 2014)

LavaASU said:


> Are you allowed to buy used or B stock?



On small purchases yes, but this is going to be big enough to require a formal bidding process in which case used/B stock is out.


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## LavaASU (Dec 3, 2014)

gafftaper said:


> On small purchases yes, but this is going to be big enough to require a formal bidding process in which case used/B stock is out.



Whats your anticipated budget like?


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## gafftaper (Dec 3, 2014)

I currently have about $15k I could spend on this. But as I said, I just need to save up for it. I'm assuming I'm going to need a minimum budget in the high $20k to low $30k range to complete this. That's a lot of money, but I can save that up in 2-3 years.


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## ruinexplorer (Dec 4, 2014)

There's no hard and fast rule as to how bright a projector needs to be based on the size of the screen, just what is visible to the audience. A rear screen will offer you the opportunity to have a lower output with the same results. The human eye is most concerned with varying degrees of light to dark as compared to color or resolution. When we use front projection, the projectors need to compete with ambient light much more, ultimately causing us to exponentially have brighter and brighter projectors, especially when not using an actual screen. However, with rear projection, much of the ambient light will spill through the screen, lessening what needs to be compensated for, plus the grey material helps to boost contrast. 

There are a couple things to consider when using short throw lenses. You will have less lens shift (if your projector is equipped with it at all) than with a standard lens. The image will likely not have perfectly squared sides due to the optics required. This will be particularly frustrating when blending an image. You also will have much less forgiveness in off-axis alignment. In reality, they don't want to be off-axis at all for your focus and keeping an even field.

Remember that when you are considering the distance, that is from the lens. So when calculating your throw, you need to keep in mind the size of the body of the projector and the space behind it required for proper airflow. In reality, I don't see the plausibility of straight rear projection with even only two projectors. Likely, you will need to use a dual mirror system like this. Even with first surface mirrors, you will lose some brightness.

When I have some more time, I'll see if I can offer you more hard and fast recommendations.


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## gafftaper (Dec 5, 2014)

So a dumb question about edge blending: My screen is 18'x32'. So is the idea that I find three projectors which can do an 18'x10' image, flip them on their side and blend to create an 18'x30' image? That seems really difficult for so many reasons. On the other hand the dual mirror system looks easy to setup and work with. Heck I could make the whole thing portable and run it all from a laptop back stage avoiding the need for any professional installation which would keep the costs down a lot. On the other hand, storage when not in use would SUCK.


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## LavaASU (Dec 5, 2014)

gafftaper said:


> So a dumb question about edge blending: My screen is 18'x32'. So is the idea that I find three projectors which can do an 18'x10' image, flip them on their side and blend to create an 18'x30' image? That seems really difficult for so many reasons. On the other hand the dual mirror system looks easy to setup and work with. Heck I could make the whole thing portable and run it all from a laptop back stage avoiding the need for any professional installation which would keep the costs down a lot. On the other hand, storage when not in use would SUCK.



Nope, the idea is you find 3 projectors, that make a 18 x 13.5 image, filp them on their side and blend to create a 18 x 32 image. With blends, you have to have an overlap area where one image fades out and the other fades in. You do not need a professional installation either way. Keep the system portable so you can do other fun stuff with it if you want (ever seen KA... I know you can't do the live video creation stuff, but you could try using projection as lighting or using video on windows, ect).

I'd look at scaff to put the projectors on. Theres a couple of free programs for blending plus the warpalizer thing I mentioned. Run 5 wire BNC (RGBHV) and you can do long runs if needed or run it from backstage.


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## ruinexplorer (Dec 6, 2014)

Honestly, I wouldn't try for having projectors on their sides. You actually have much fewer options of manufacturers (and models) that allow for it, plus you will get less lamp life doing so. I would instead be trying to make a 24' wide x 18' high image with two projectors, giving you as much blend as you want (up to 25%) and letting the excess bleed into the traveller.

EDIT: You may want to check with your vendors, many of them will deal in B-stock directly from the manufacturer. This way you can get current models for considerably less and have it fit in with bidding.


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## gafftaper (Dec 22, 2014)

I've got some free time so I'm back into looking at this project. 

I ran the numbers on the Panasonic ET-D75LE50 lens. It would take a 22.5' throw to fully fill my 18'x32' screen. I've got 14' of space between my rear wall and the screen. If I can use one of these mirror systems like the one below to stretch my 14' throw to up over 20' throw, I should be able to fill most of my screen to full. 

So, next question is can I get a projector bright enough to actually handle the task of mostly filling that screen? So my next question for you is how many lux do I need on that screen in order to not have my rear projection screen washed out by a full wash of stage frontlight?


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## MNicolai (Dec 22, 2014)

gafftaper said:


> So my next question for you is how many lux do I need on that screen in order to not have my rear projection screen washed out by a full wash of stage frontlight?



44,300 lumens for a target contrast ratio of 10:1, ambient light of 10fc, and optimistically assuming your screen gain is 1.30. I'm going to bet you don't have $150,000 sitting around for this project though, so best to resign yourself early on to knowing you won't be using this screen for cinema simultaneous to stage lighting anytime soon.

If you are aiming for cinema without stage lighting, then you don't need nearly as many lumens. But throw that stage lighting into the mix and now you've got to ramp up your projector brightness.

Also, whichever lens you pick, you want to be on the wide angle end of it if it's a zoom lens. You can lose upwards of 60% of your lumens by choosing a lens/throw combination that puts your zoom ratio at the narrow end of the lens.


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## Footer (Dec 22, 2014)

gafftaper said:


> I've got some free time so I'm back into looking at this project.
> 
> I ran the numbers on the Panasonic ET-D75LE50 lens. It would take a 22.5' throw to fully fill my 18'x32' screen. I've got 14' of space between my rear wall and the screen. If I can use one of these mirror systems like the one below to stretch my 14' throw to up over 20' throw, I should be able to fill most of my screen to full.
> 
> So, next question is can I get a projector bright enough to actually handle the task of mostly filling that screen? So my next question for you is how many lux do I need on that screen in order to not have my rear projection screen washed out by a full wash of stage frontlight?



15k for a dark room. If you want to even think about using it while anything else is on your looking at 20k+... and even then your talking about a dim wash or a podium mic type thing. Your going to be looking at a 50,000 dollar plus projector.... and a VERY expensive lens. When you get to these short throw distances it is worth it to take the time to see about front shots. 

How often do you see yourself using this system? Do you have the cash to get the proper cabling and switching gear? A good switcher can run 10 grand. You are also looking at a nearly a 1,000 dollar lamp every 3,000 hrs. 

Not saying it is not worth it, but really take a look to see if it is. In our space we own a small 5k projector and a 9x12 for doing random things. After that, we rent a system. Our shows vary so much that not one system could cover everything. Screens move, inputs change, and we have to deal with that. It costs about a grand a show but we get the right screen size for what we need, the switchgear needed, and the right lensing for the show. 

I'm still in the "you have too big of a screen" camp on this. Who is the actual users of this system going to be most of the time? The renters or the school? If it is the school... go for it. If it is the renters... screw it. Get a hold of a good video vendor and walk them around. Odds are if they know they will get steady work from you they will give you a decent deal for a rental and you can bill it to the client. Everyone wins.


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## gafftaper (Dec 23, 2014)

I'm looking at projector calculators on line. How many lumens/lux of light do I need to actually have on the screen in order to be seen with a full wash? 

As for your question Kyle, I have about 8 or 9 productions every year here by my own school and other schools in the district. All of them really want to use projected backgrounds and keep trying to do front projection on my cyc... with less than acceptable results. So it's worth doing and I would be able to pay for it with money from rentals. Again this is a project which requires several years of saving up budget to pay for and while I wait the technology will get cheaper. My goal at this point is to educate myself enough to understand what I need and to get a rough price in mind. That way I don't have to drag a dealer in to do a bid which I won't act on for a couple years.


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## robartsd (Dec 23, 2014)

gafftaper said:


> I'm looking at projector calculators on line. How many lumens/lux of light do I need to actually have on the screen in order to be seen with a full wash?


The brightness needed would depend on how much light _your_ full wash puts on _your_ screen. If you have a light meter, you might put up a wash and measure the ammount of light that reaches the screen that you would have to compete with. The target contrast ratio will ultimately determine the needed brightness.


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## sk8rsdad (Dec 23, 2014)

FWIW, this is a Panasonic PTDW6300US (6000 lumen) with an ETDLE080 front projecting from LX1 (approx 28' away and 16' off the deck). They're from one of the dance recitals from years gone by so no tech rehearsal to tune anything and the camera was likely optimizing for faces. Note that the actors aren't casting any shadows on the back wall as long as they stay upstage, and in the crowd scene the shadows are blocked by the actors.

It's certainly not professional quality but might be a more reasonable approach than trying to engineer a solution for a 14' throw.


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## ruinexplorer (Dec 23, 2014)

MNicolai said:


> 44,300 lumens for a target contrast ratio of 10:1, ambient light of 10fc, and optimistically assuming your screen gain is 1.30. I'm going to bet you don't have $150,000 sitting around for this project though, so best to resign yourself early on to knowing you won't be using this screen for cinema simultaneous to stage lighting anytime soon.
> 
> If you are aiming for cinema without stage lighting, then you don't need nearly as many lumens. But throw that stage lighting into the mix and now you've got to ramp up your projector brightness.
> 
> Also, whichever lens you pick, you want to be on the wide angle end of it if it's a zoom lens. You can lose upwards of 60% of your lumens by choosing a lens/throw combination that puts your zoom ratio at the narrow end of the lens.


 
I'm not sure where you are getting such high numbers for the lumens since this is for stage projection, not cinema. I have only 50% more lumens for front projection, not on a projection screen, with a projection area around six times the size of what is needed here. With a front projection, at 10fc, the contrast ratio of the projector will drop to about 55% of that with no ambient light, requiring a much brighter projector. However, with a typical rear screen, you should still have close to 75% of that same contrast ratio. You would have to get up to around 25fc of ambient light on the rear screen to drop the contrast to the same level as that on the front screen.

Obviously, you will want a projector that will be a good general use projector as you don't know what content will be used from production to production. What you will quickly learn is that you want to design for what you have. The brightness and contrast required for cinema viewings is different for that of a typical projected set. Then again, with cinema, you shouldn't need to worry as much about the ambient light.

Also, there are some things to be wary of when considering ANSI Lumens. This is calculated using a full white field. You will likely never project this. Not all images will maintain color brightness as they do white brightness. The biggest culprit of this will be a single chip DLP projector. With a three panel LCD or three chip DLP, each color will be represented at the projector refresh rate. However, with a single chip DLP, the color brightness drops significantly due to the fewer times the color is represented during a single cycle. Here is a good primer on what I am talking about.

Not knowing the specifics of your screen (it should be printed on a label on a lower corner of the back), it is difficult to say exactly what you will need. That being said, you should be able to get away with 12-15,000 lumens if you were sticking with brighter images, but I agree with @Footer that you may want to look at a 20,000 lumen projector (like this or this). Mind you, the $50-75k price range will be average. You will really need dealers who will look at B-stock when posting bids.

One thing about contrast, when looking at the specs, watch out for overly inflated contrast ratios. The way that the sales literature will show an extremely high contrast ratio (advertised as dynamic contrast) since that can be what the uninformed may be looking for, is that to get the ratio, the projector will likely need to dim up to 50% of the stated ANSI lumens. Here is a nice warning article when seeing this for HDTV sales.

You will need to be more creative with your lighting designs to ensure the lowest amount of ambient light on the screen. This will often mean greatly diminishing lighting from FOH. Also, depending on the gloss of your floor, you may need to consider a variety of masking to reduce bounce. So, while this is opening a creative new world, you need to make many considerations to how you do productions.


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## gafftaper (Dec 24, 2014)

Thanks guys. I'll do some more reading from Ruinexplorer's links. I need to find out our policy about buying used/B Stock gear, I'm seeing used, 3 chip, 20k projectors starting below $20,000 from places like Gearsource/Solaris and B stock for not a lot more. If I can go with one of these options this becomes a lot more affordable.


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## Esoteric (Dec 31, 2014)

We use ProPresenter and Matrox Dual/Triple Head2Go products to edge blend on a budget all the time. Works like a charm.

Mke


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## Jay Ashworth (Jan 1, 2015)

There are, and I don't know off hand exactly who makes them, full color laser-beam projectors: they actually combine 3 Q-switched mono-spectral R G and B lasers into a collimated beam, and then scan it, usually using a pair of rotating mirror drums or something similar.

They have ridiculous throw distances, and are in focus *everywhere* -- I am told they use one to project moving video on the side of Stone Mountain in GA -- and keystoning them wouldn't be hard either, even for really steep angles.

If you have a fair amount of cash to throw at this, and didn't know these existed, they might be worth some research.


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## rphilip (Jan 5, 2015)

ruinexplorer said:


> Not knowing the specifics of your screen (it should be printed on a label on a lower corner of the back), it is difficult to say exactly what you will need. That being said, you should be able to get away with 12-15,000 lumens if you were sticking with brighter images, but I agree with @Footer that you may want to look at a 20,000 lumen projector (like this or this). Mind you, the $50-75k price range will be average. You will really need dealers who will look at B-stock when posting bids.
> 
> One thing about contrast, when looking at the specs, watch out for overly inflated contrast ratios. The way that the sales literature will show an extremely high contrast ratio (advertised as dynamic contrast) since that can be what the uninformed may be looking for, is that to get the ratio, the projector will likely need to dim up to 50% of the stated ANSI lumens. Here is a nice warning article when seeing this for HDTV sales.



A couple thoughts, my university just purchased a Panasonic PT-DZ21KU and the street price listed at http://www.projectorcentral.com/Panasonic-PT-DZ21KU.htm is close to what we paid. We are shooting it on a 25'x15' front projection screen in a 650 seat classical music hall.

My gut feeling is that this is about the right size projector for you also.

To help figure out how bright of projector you need you can do some experiments with a smaller projector on a section of your screen. If, for example, a 5k projector gives a good image on a 9x16 section of your screen then a 20k projector will look pretty much the same on the full screen.

Do keep in mind however that the lamps loose brightness as they age. I did a measurement when replacing lamps on another projector recently and at ~1800 hours use (2000 hour life) the lamps had dropped to 50% of the brightness of the new lamps.

At Infocomm last year Panasonic also showed a 0.38 throw ratio lens for their large projectors, http://panasonic.net/avc/projector/products/d75le90/ this lens would let you mount the projector up and behind the screen. Do carefully work out from a cross section drawing to make sure that nothing would be in the way.

Hope this helps

Philip


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## JChenault (Jan 6, 2015)

There is one aspect of short throw RP projections that I have not seen discussed here. ( note this is not really my field, but it is my understanding of the physics). It could be that RP manufacturers have solved this problem since I last did any serious projection, so read this with a grain of salt. If anyone knows that this analysis is a load of excrement, Please post your thoughts. I would love the correction.



Any short throw RP screen will tend to have a bright center and dim edges. Why is this?

Consider the RP material and a beam of light from the projector ( at the left of the picture ) 




When the beam hits the RP material, it diffuses somewhat, but the majority of the light energy is near the axis of the original beam. In this sketch, the intensity of the light is depicted by the length of the arrow.

Now consider a RP with a very wide angle projector.



That we care about is how much light reaches our observer on the right. Due to the way the RP material scatters the light, the light hitting the edges of the screen will mostly continue in a straight line and only the edge of the diffused light will hit the observers eye. This means that the edge of the screen could be substantially dimmer than the center to outright observer.


This is one reason that using multiple projectors with edge blending will give you greatly improved intensity than a single bright projector with a wide lens.


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## ruinexplorer (Jan 6, 2015)

John, this is somewhat correct. A lot will depend on the screen gain. The various types of screen will either focus the light or spread it. This is a direct correlation to the viewing angle and is true of both front and rear screens.


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## Calc (Jan 6, 2015)

Once you get to the pricing stage, make sure you check to see if your district has any deals with certain manufacturers. Here we have a deal with Epson. They bargain price everything for us, so we buy just about all of our projectors through them. I'm sure they make up for the discounts by volume.
The only exceptions I can think of were for a pair of 11k's we needed with a 200' throw to a 10'x14' screen. Pretty much the opposite of the problem you have here!


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## JChenault (Jan 6, 2015)

ruinexplorer said:


> John, this is somewhat correct. A lot will depend on the screen gain. The various types of screen will either focus the light or spread it. This is a direct correlation to the viewing angle and is true of both front and rear screens.



(exposing my ignorance here)
I'm confused.

My understanding of gain is that it is a measure of ( in a front projection screen) of how much light is directed back to the source. My mental model is 'How much of the crystals that they use in road signs that bounce the light back to your headlights have they mixed into the surface. From my college physics I have a memory of how those crystals work.

I can't wrap my head around how you could have a similar definition for an RP system. IE is the 'gain' of an RP system a measure of how much the light is scattered as it passes through the RP material ( in which case I can't understand how it could focus the light) -OR - can the RP be constructed such that the light that hits the extreme edge of the screen is re-focused back toward the center. If the later I can see how if could be said to focus, but I am very curious about the physics of the material as I can't see how it could work.

Could someone clear up my confusion please?


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## ruinexplorer (Jan 7, 2015)

John, don't worry, many people get confused about screens and their differences. Here's a great explanation of the definition of gain and the variety of screen materials and how they affect the image transmission. You will note that on the Diffusion Rear Projection page that this aligns with your physics proposal.

I should mention that for projection standards, we are most concerned with the image that makes it to the eye of the viewer. So, this is why just knowing how bright a projector is, or it's stated contrast, gives us an incomplete set of data.


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## JChenault (Jan 8, 2015)

ruinexplorer said:


> John, don't worry, many people get confused about screens and their differences. Here's a great explanation of the definition of gain and the variety of screen materials and how they affect the image transmission. You will note that on the Diffusion Rear Projection page that this aligns with your physics proposal.
> 
> I should mention that for projection standards, we are most concerned with the image that makes it to the eye of the viewer. So, this is why just knowing how bright a projector is, or it's stated contrast, gives us an incomplete set of data.




Excellent article. Thanks.

One question. Do they make optical RP screens in the kind of sizes gafftaper is talking about. Ie at what point does this become an unworkable approach?


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## ruinexplorer (Jan 8, 2015)

I know that it is possible, depends on the manufacturer. Obviously, the price becomes prohibitive to many way before a they reach a screen that size.


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## ruinexplorer (Jan 11, 2015)

So, at CES I saw the Panasonic PT-DZ21k projector with the ET-D75LE90 Lens (0.36:1, fixed) that would fill the screen at about 10.5' throw. It is a 20,000 lumen projector. You would likely need to fly the projector since the bottom of the image would be about 9.5' above the projector if it was sitting on the ground.


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