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Topic: Auditorium, curved screen, long throw
Joined: Mar 17, 2006
Posts: 1
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I'm trying to spec out a projector for an auditorium. It seats about 450 and the throw from the location where we'd mount the projector is approximately 55 feet onto a large (approximately 40' wide x 25' high) screen. The screen is permanently mounted, is made up of a reflective material with small holes in it and has a noticeable curve to it. I haven't measured it but I'm guessing it's less than a foot concave over the width.

I'm not an AV guy, I'm the IT guy who has to handle everything that appears to use electricity or connects in some way to a PC, so please bear with me if these questions are on the naive side.

From some reading and web surfing I've done, I'm thinking I'll need a minimum of 5,000 lumens and will need a long-throw lens. Should I be concerned about the curvature of the screen? I'm hoping that the difference between the sides and center would not result in a noticeable focus problem, but don't know that. I also haven't seen any lenses that specify a curved target.

I'm also open to recommendations for equipment to get the signal from a PC on the stage up to the projector. I'm looking at solutions from Crestron and NTI that would put a VGA (1024x768 minimum) or HDTV signal (from a DVD player) through Cat6 wire for the run from the stage to the projector. The reason I'm looking at Cat6 is that I have lots of it and it's much cheaper than bulk video cable.

We will have to support presentations from PCs and also possibly project movies from a DVD player. I'd like to have a projector I can support/monitor/control over the network, since I will end up supporting this and don't want to have to run across campus to the auditorium if it's not necessary.

Thanks in advance for any advice/assistance!

[Edited by CrunchyWizard on Mar 17, 2006 at 8:44 AM]
Joined: Mar 28, 2005
Posts: 13,165
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The goal is to have a minimum of about 12 lumen per square foot... Do the math on that...

40x25 = 1,000
Times 12 lumen...

12,000 lumens

Yes, you read that correctly, and no, I'm not kidding. If I were specifying the projector for you I would be looking in the $20K range or a good deal more for a suitable projector.

Here is a list of 10,000+ lumen projectors... Sanyo hits the best price and will likely be on the street right around $20K. The others, like the Christie are truly designed for screens that size.

5,000 lumens is often a 12 or 14 foot diagonal board room screen with some florescent lighting. It is NOT a 50 foot diagonal digital cinema lumen level.
AV Integrated - Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.
Joined: Mar 23, 2006
Posts: 4
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Sanyo PLC-XF45
Projector Specs
Hi Alan,

First of all for converting VGA to cat5 lots of companies do boxes for that.

Kramer do the TP-121 for the sender and the TP122 for the receiver. Look at their web site for information. They say it will run 100m, but I have run it longer than this in the past. You can get very cheap senders and receivers, but you get what you pay for, maybe also look at Extron.

If you need simple switching from VGA to video, use the Kramer VP-740. This has DVI inputs and outputs, you can also attach composite video, S-Video, VGA and do a seamless switch between them. Obviously run the output of this through the CAT5 converter.

I'm sure if you can get a DVI-CAT5 box, don't know who from, or you use the Kramer VP720DS switcher which has VGA input and output.

For a 40' wide image you would get an image height of 22'.5 (16:9).

You say the throw is 55 ft, so you would need a 1.375:1 lens which is quite wide but you can get 0.8:1 lenses.

As the last post says, you will need a large projector for this, over 10,000 lumens. Again the Sanyo do the best price range, you would get away with the Sanyo XF45, 10,000 lumen with a 1.35-1.75 Short throw zoom lens.
You would need to check your dimensions though because for a 40' wide image with this lens you would need between 54' to 40' from the front of the lens and it is best to give yourself margin in this.

If the budget is there then I would recommend a 12-20K projector, but you should be able to get a Sanyo dealer to bring a demo projector and lens to see what the XF-45 will be like. I believe some of the Christie and Barco projectors have built in warping capability, but they are 3 time the price of Sanyo.

The bend in the screen is going to be an issue. In the middle the throw will be longer so the image will be larger, this will give an oval effect to the image. You need a curved screen controller (warping unit) like a Silicon Optix IA-100BEX warping & edge blending unit. This will only need to be set up once, but you will need someone who knows what they are doing. There are other manufactures of these (like Barco) but they cost a fortune compared to this one.

Please note this reply is based on a budget system, if you want high definition results you will need a serious budget, and get an expert in !!