[Christopher Ellington]

Hi. I wanted to know, based on all of your experience and knowledge, can I utilize one projector to fill one 25ft rear projection screen? I wanted to know if the math works as simple as moving a short throw projector back more beyond the minimal throw distance to enlarge the picture. Does that reduce the quality, create distortion and dim light too much?

I ask because we want to purchase a large projection screen to fill our stage area which would be in the 25ft range. However we only have about 5 to 6ft of workable space for a short throw projector behind it. If a short throw projector can give about 8ft of image at about 1ft away, could I get 24ft of image at about 3ft away?

I am trying to avoid having to seam together one image with multiple projectors.

Thanks

C

 

[dbpaddler]

If you have 10 1/2 feet behind, the Optoma EH460ST can give you a 24ft screen and has about 4000 lumens. Not sure if that's enough but it's a lot brighter than you'd get from any UST I can imagine. It's a 1080 projector so of course it's not going to be tack sharp at 24ft.



Sent from my SM-N960U1 using Tapatalk

 

[bud16415]

Hi. I wanted to know, based on all of your experience and knowledge, can I utilize one projector to fill one 25ft rear projection screen? I wanted to know if the math works as simple as moving a short throw projector back more beyond the minimal throw distance to enlarge the picture. Does that reduce the quality, create distortion and dim light too much?

I ask because we want to purchase a large projection screen to fill our stage area which would be in the 25ft range. However we only have about 5 to 6ft of workable space for a short throw projector behind it. If a short throw projector can give about 8ft of image at about 1ft away, could I get 24ft of image at about 3ft away?

I am trying to avoid having to seam together one image with multiple projectors.

Thanks

C

A 24’ screen is about 246 sq ft. with rear projection in a theater setting with stage lights on the front side and some house lights I would take a guess you will need 50 FL foot lamberts min brightness or 50 lumens per sq ft. 50x246= 6,300 lumens. Better yet would be to target a projector in the 10,000 lumen range. It all depends on what material you use for a rear projection surface. They should be able to give you the light loss factor.

Sometimes the throw distance of a ST short throw not an UST ultra short throw can be increased with using a mirror to reflect the image off of. That’s how USTs work anyway.

 

[dreamer]

A 24’ screen is about 246 sq ft. with rear projection in a theater setting with stage lights on the front side and some house lights I would take a guess you will need 50 FL foot lamberts min brightness or 50 lumens per sq ft. 50x246= 6,300 lumens. Better yet would be to target a projector in the 10,000 lumen range. It all depends on what material you use for a rear projection surface. They should be able to give you the light loss factor.

Sometimes the throw distance of a ST short throw not an UST ultra short throw can be increased with using a mirror to reflect the image off of. That’s how USTs work anyway.

That is some funky math. 50x246 = 12,300 lumens if the gain was 1.0

 

[bud16415]

That is some funky math. 50x246 = 12,300 lumens if the gain was 1.0

I thought that looked too low when I typed it. I better get new batteries, lol. Thanks for checking my math.

I said 50 FL because I assumed the gain on a RP screen would be lower than 1.0 by a lot.

I think these issues are why we don’t see many RP setups for low budget stage shows.

 

[Christopher Ellington]

Thanks guys. Though I hear that moving the projector (like the Optoma EH460ST) back too far can cause vignetting. I'm not sure I'd be able to tell how bright I need the projector without trying it out. Technically we really just have about 5ft to work with or else we'd have to lose more of our stage by getting a projector further up. Further up also means further into the light which can be an issue.

I actually thought that rear projection would be less impacted by stage lighting in front of the actual projector?

 

[Dave in Green]

A simple rule of thumb is that the shorter the throw of a projector's lens system the more difficult it is to produce a larger image that is consistently sharp. The geometry of longer throw lenses makes it easier to maintain consistently sharp images at larger sizes. That's why honest projector companies always suggest smaller maximum image sizes for their shorter throw models than for those with longer throws.

To produce a quality 24' diagonal image on a rear projection screen in stage lighting with a 5' throw would require an industrial strength professional projector with a high quality short throw lens that would cost in the tens of thousands of dollars. You should really consult with an AV professional experienced in stage show setups. This isn't something that an amateur relying on casual forum advice is likely to be able to pull off.

Maybe @AV_Integrated will chime in and offer some professional advice.

 

[bud16415]

You have to both understand the products and understand the science of projection. You then have to understand the goal you wish to achieve.

One method you are alluding to is experimentation. That is a great method but also expensive if you have to buy a lot of stuff to find out it doesn’t work. You could mock up just a section of the screen using a sample of the material you are thinking of making the screen from. And then find any projector around (Classroom etc) to set back the distance required to make an image that big. Turn down the house lights and see if that little test area is bright enough for your needs.

Some of us like I did with my flawed arithmetic were trying to suggest just how bright you might need even if the setback of the UST would work ok.

 

[bud16415]

@Dave in Green The thing about a stage show is they might not care if the image is sharp or even bright enough. If they are throwing up clouds or trees or just changing from night to day they could blend stage lights from the front with projected light from the back.

It wont be cheap for sure nor will the screen if it is a commercial grade RP screen.

As far as I know budget hasn’t been mentioned.

 

[Dave in Green]

^ True, for fuzzy dim special effects images that no one will really be looking at a relatively cheaper setup might work. If the audience is expected to actually view and be impressed with the image quality it's a whole different ballgame. So the type of image and purpose to the show would need to be clearly defined.

 

[Christopher Ellington]

We're hoping for something in the $3000 range to propose. This really isn't a tens of thousands of dollars job. More an annual stage refresh that we normally budget $500 to $1000 for and we're pushing that budget as I would really like to try some form of a screen behind the preacher/worship band that shows the graphics/imagery in better color as well as being able to change the graphics behind on the fly based on a worship song or sermon topic series.

I try to keep a stage setup for a year or so. So we'd hope to get some use out of it. When I started this position, they'd been changing up the stage for every series (just about every 6 weeks). I pretty much established a stage layout to last a year and use environmental projection to create different looks as I am primarily a graphic/visual artist, photographer and videographer. We're now at that one year mark where I'd like to change the stage set. The projection we had got very washed out from stage lights and the color didn't really come through on camera.

So I was looking at this Carl's Place Carlofet site which has become popular for those with smaller budgets to get a screen. I'd identified a screen that could be about $1000. Then I see the recommendation for something like Optomo EH460ST for a little over $1000. We already have our Pro Presenter setup with the ability to control this center rear projector.

We're not yet in a position to make a major investment (we're working on that), but I wanted to see what we could achieve for a few thousand while getting some legs from it through changing graphics/scenery for kids events, etc.

 

[Dave in Green]

For a church on a tight budget I would strongly recommend sticking with front projection for a 24' screen. Front projection screen material will cost less than rear giving you more to invest in a properly bright longer throw projector designed to produce a consistently sharp, colorful image. Trying to do a big rear projection setup on a tight budget is not going to give you the results you imagine. The most important thing with either front or rear projection is to keep as much ambient light as possible away from the screen. Invest some time and a little money if necessary to make sure that all the church lighting is properly managed to remain away from the screen area as much as possible. Don't try to reinvent the wheel for what so many other churches have successfully used.

 

[Dave in Green]

For a brighter, longer throw projector I'd suggest something like the Epson PowerLite 2250U. It's rated at 5,000 lumens vs. the Optoma EH460ST's 4,200 lumens. The Epson is also 3LCD, which means it won't produce DLP rainbows like the Optoma which can be annoying to some in a large group of churchgoers. If mounted at its minimum throw from a 24' diagonal 16:9 aspect ratio screen (29') it would be noticeably brighter and more colorful than the Optoma on a rear projection screen. A PowerLite 2250U plus a 24' front projection screen should cost roughly the same as the Optoma with rear projection screen and be a much nicer overall combination. I believe Epson also gives discounts to houses of worship. You should be able to put this together for

 

[AV_Integrated]

The only way to do this is with a Panasonic professional projector and their ultra short throw lens. The lens itself is WAY over your total budget, ignoring the projector.

You aren't going to get there from here and while I understand your request, your end goal is completely unrealistic.

To get a 25' wide image, which is the size of the screen in some commercial theaters, which have completely blacked out rooms, you need a ton of light output (think 12,000+ lumens) and then you will need the ultra short throw capability.

Neither of these things is 'NORMAL'. Normal is a 100" to 133" diagonal image that is produced by a projector 10-20 feet from the screen.

So, when you fall into a niche, then prices shoot up. In reality, the prices skyrocket when you are talking about a large setup requiring a lot of brightness and a throw distance that is extremely short.

You may have some luck with what NEC and some others offer in terms of edge blending, but I even think that is way outside of budget.

Yes, this will require (ABSOLUTELY REQUIRE) multiple projectors on the budget you have. You likely need to look into commercial ultra short throw models, but I think you will be fighting limitations of image size with almost all the projectors that will be within your budget. But, should you find one which can hit your screen height, then you will need multiples to cover your width.

I'm not sure I saw a mention of your screen height. This can sometimes be 16+ feet in a on-stage setup.

At the end of the day, what you are asking for is not a 'cheap production' setup. It may not have a high dollar budget, but what you are specifically asking for is a very high dollar request.

This is why most stage production use painted backdrops on rollers that their own people paint themselves. It is within budget, has no issue with ambient light, and does the job.

Maybe you can get something setup, but I wouldn't dream of spending any money on any product without first seeing what rear projection looks like with a borrowed projector on rear projection film under stage lighting to make sure it was acceptable and a path that I wanted to pursue a lot further.

 

[Christopher Ellington]

Thanks for your help guys!

I agree and the more research I do, I realize it's unrealistic to expect a cheap option of a projector that will effectively image on a 20+ ft screen at a short distance.

I reminded myself that we have a Hitachi CP-WX9211 not being used in the back of the space. I am going to see what that color and quality produces if we were to put a front projection screen high up instead of trying to make a video wall at floor level. I don't think we're ready to do that "right" just yet.

I am working on digital mockups o the stage design that reflect things that we realistically could do.

 

[wheelee]

just want to share this ginourmous screen (22x40ft)
they say it was using 2X 33000 lumens Christie for the movie Felix Manalo shown in the Philippine Arena (worlds biggest dome arena)

 

[Dave in Green]

The Hitachi CP-WX9211 isn't full HD resolution but it is really bright -- 8,500 rated lumens. It will give you an idea of how many lumens you need to achieve acceptable brightness with a big screen. If you decide you need 8,500 lumens and want finer resolution, full HD projector costs go up sharply once you get over 5,000 lumens.

Also, I may have missed it but I didn't see whether the 24' dimension was specified as width or diagonal. We typically express video projection screen size in diagonal, same as TV. But some people go by width when getting into the larger sizes, so it needs to be specified to avoid confusion. It also helps to know aspect ratio, i.e. 4:3, 16:9, etc.

 

[Christopher Ellington]

The Hitachi CP-WX9211 isn't full HD resolution but it is really bright -- 8,500 rated lumens. It will give you an idea of how many lumens you need to achieve acceptable brightness with a big screen. If you decide you need 8,500 lumens and want finer resolution, full HD projector costs go up sharply once you get over 5,000 lumens.

Also, I may have missed it but I didn't see whether the 24' dimension was specified as width or diagonal. We typically express video projection screen size in diagonal, same as TV. But some people go by width when getting into the larger sizes, so it needs to be specified to avoid confusion. It also helps to know aspect ratio, i.e. 4:3, 16:9, etc.

Thanks. I'd be going for a screen around 24ft x 11ft,

So after having some more time there today, I confirmed:

We have x3 Hitachi CPX8170 projectors for our environmental projection. My tech notes that they are on short throw lenses from far back (about 150ft) which is probably reducing the overall quality and light.

We then have x3 Hitachi WX9211 projectors for our lyrics, videos, slides, graphics, etc. Those are extremely colorful, clear, etc. We have only been using the two side ones, so I tested out the center one and it gives the color and saturation we need to do what I want.

My question now is that I still want to use screen that's about 27ft x 11ft. I do want a long width projector, but not necessarily 16x9. I want a little more narrow width length to it.

The good projector has a lens that only allows the picture to get as large as about 16ft from where it is. Since we have three, I can always edge blend two together. However, I'd like to find out if this Hitachi WX9211 projector will allow me to "cheat" the image size via some form of digital zoom beyond the lens so we can keep the other two available. Even at the loss of some quality. I'll need to get back there when I have time to go through all of the menus to see if that's a feature. I know they have a magnify feature, but I don't know if that's a temporary magnification for checking or a way to push the picture size a bit. There's some railing in the balcony where our projectors are that would get in the way if we moved it back more.

I'm actually thinking about using our spare coroplast sheets (we have about 15 full 8ft x 4ft) to make some sort of creative screen.

 

[Dave in Green]

The Hitachi CPX8170 is lower native resolution (1024x768 pixel) and 4:3 native aspect ratio whereas the WX9211 is higher native resolution (1280x800 pixel) and 16:10 native aspect ratio. The WX9211 is also 1,500 lumens brighter so it's clearly the superior model for your use. Ideally you would move the mounting location back in order to allow it to fill your desired larger screen size. I don't know of a way to digitally expand the image beyond the projector's maximum image size capability from a given distance. That's a factor of the lens system. There are optional lenses available for the WX9211 that might allow you to reach your desired image size from the current mounting location. Following is a list of available lenses from Hitachi. If you decide to go that way you'd need to have the exact throw distance (lens to screen) and exact screen size to determine which of the following lenses would work best:

LL-905 Long Zoom 3.70:1-5.90:1
ML-904 Middle Zoom 2.50:1-3.80:1
SD-903W Standard Zoom 1.70:1-2.60:1
SL-902 Short Zoom 1.20:1-1.80:1
UL-906 Ultra Long Zoom 5.80:1-9.20:1
USL-901 Ultra Short Zoom 0.80:1-1.00:1

As far as a screen with a wider aspect ratio than the projector's native aspect ratio, the full image the projector is capable of producing wouldn't simultaneously completely fill the screen in both the horizontal and vertical. If you are projecting custom images to be projected then you would want to produce them to be the same aspect ratio as the screen. If you are projecting existing images of a standard aspect ratio the screen should have the same aspect ratio as the images in order to be filled both horizontally and vertically.
@AV_Integrated has a lot of experience with setups like yours so his advice will be helpful given this new data.

 

[AV_Integrated]

So, when I read all this I see that you already have projectors with a MSRP that comes in around $35,000, not including the required lenses for them. Especially with the WX9211, this is far more in line with where you need to be as 3 of these projectors can hit about 25,000 on-screen lumens, which is exactly where you want to be for excellent presentation.

Now, with a 27x11 screen size, you aren't working with a standard aspect ratio, and the proper setup really requires that you use edge blending to seamlessly join 2-3 projectors together into a single image that covers your background accurately.

The 9211 lists this as a feature of the projector. With the price point and the light output, it is NO surprise to me that this projector does so. As well, it features HDBT input, so it can handle long run video transmission over category cable.
https://www.projectorcentral.com/pdf/projector_spec_8147.pdf

Now, if you were to get three of the ultra-short lenses for the 9211, you still need about 14', lens to screen, to fill the height of 11'.
https://www.projectorcentral.com/Hitachi-CP-WX9211-projection-calculator-pro.htm

I can promise you, that you aren't getting 3 of their ultra short lenses for anywhere near $3,000. You also need twice the distance that you have to actually get the 11' height that you are after.

There's nothing wrong with wanting to do this, but you really should take the 3 9211 models you have, make sure they are setup for a proper edge blend across all 27', and then run an image to them.

Total price: FREE

The options from there aren't pretty. I mean that they are downright ugly in terms of cost, because the reality is that you almost must use Panasonic projectors with their uber pricey ultra short throw lens. Their lens can hit that 11' height from just seven feet away. This still doesn't actually fit your needs, but it's about as close as you can possibly hope for in this situation.

More realistic, overall, if the projectors are completely hidden with rear projection, would be to do a pretty intricate setup of 6-8 or so projectors all edge blended and color matched to handle both height and width across the entire space. These projectors could be dimmer overall (5,000 lumens or so) while still producing an amazing image due to the quantity in use.

I don't really see any good options here beyond the very good projectors which are already owned, paid for, and delivering 8,500 advertised lumens.