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Author Topic: Large Screen Video  (Read 6819 times)

Bob Cap

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Large Screen Video
« on: December 14, 2005, 06:09:38 pm »

Anybody here into large screen video projection?

I have a Church that we are putting a sound system into that is now interested in a large screen (16' wide x 12' high) video projection system.

The quirk is the projector has to be at the back of the church, 60 feet away.

Any suggestions? Any web sites to look at for calculating the size of projector needed?

Thanks

Bob Cap
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Aaron McQueen

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Re: Large Screen Video
« Reply #1 on: December 15, 2005, 11:25:41 am »

To shoot from that far away you will probably need a long throw lens.  Also you will probably need a brighter projector than if the projector is mounted closer to the screen.  Find a good local AV retailer(not Best Buy) and ask them to demo the projector before you buy (good retailers have no problem doing this).  This way you can make sure it will reach your screen and have the necessary brightness.  I tried 4 projectors before I found the one we liked.

Also make sure you use a dual monitor setup. Monitor 1: preview and desktop, Monitor 2: projector.  Also get some good worship software like EasyWorship for projecting the words.  Despite what people may say Powerpoint is not the best tool for worship worship.
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Micheal Martinez

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Re: Large Screen Video
« Reply #2 on: December 15, 2005, 05:28:42 pm »

Bob,
I found a web site at one time that had a projector calculator on it, however I don,t remember which one it was. I think a Google search would find it pretty easily.
If you are interested my church has a 16x16' motorized remote controlled screen which has never been used and is still in the box, we would love to be able to help out another church who might need one. Let me know maybe we could work something out.

Mike
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Brian Kent Tennyson

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Re: Large Screen Video
« Reply #3 on: December 16, 2005, 11:33:23 am »

OK. Few observations, calculations and reeudcations (is that a word).

Observation. 16X12 is a standard format screen. no one should be putting these in anymore, the world is moving rapidly to wide format. Plus four line hymn phrasing lays out better on a 16:9.

Calculation. Determine your screen height by dividing the distance from the screen to the back of the room by 6 (if you are using it for small text and spreadsheets) or 10 to 12 (if you are using it for video or as a replacement hymnal). I will assume that 60 feet is the distance to the worst seat so that would give us a screen height of 6'. screen size of 6'h by 10'8"w.

To determine the lens throw ratio, divide the distance from the lens to the screen by the width of the screen. if your width is 10.68' and distance is 60' you will need a 5.6:1 lens.

Reeducations (there it is again). Distance from the screen has no effect on the amount of candlepower you will need from your projector. ANSI lumen requirements are the product of a calculation of the gain of the screen, ambient light and desired contrast. Less stray light on the screen = less light needed out of the projector.

Photons are not like sound waves, and are not noticeably affected by 60' of "clear" air. If light control is good just buy the brightest thing you can afford and you should be alright.

If you can take a light measurement of the vertical surface that the screen will be on I can do the calculation for the required brightness of the screen.
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Brian Kent Tennyson

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Re: Large Screen Video
« Reply #4 on: December 16, 2005, 11:35:16 am »

Also, Christie Digital www.christiedigital.com has a try it before you buy it program. It's worthy of checking out.
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Aaron McQueen

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Re: Large Screen Video
« Reply #5 on: December 16, 2005, 01:11:07 pm »

Quote:

Reeducations (there it is again). Distance from the screen has no effect on the amount of candlepower you will need from your projector. ANSI lumen requirements are the product of a calculation of the gain of the screen, ambient light and desired contrast. Less stray light on the screen = less light needed out of the projector.


Sorry for my lack of edumication.
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Brian Kent Tennyson

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Re: Large Screen Video
« Reply #6 on: December 17, 2005, 05:11:38 pm »

Well you're in good company, it's a very common miconception, especialy among sound system designers.
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h.s.overman

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Re: Large Screen Video
« Reply #7 on: December 30, 2005, 12:08:31 am »

Just as a benchmark so that you will know that it can be done, our church is using a Mitsubishi 5950 (4700 lumens I think)with a long throw lens to get a 10 foot wide image at 65 feet in fairly strong ambient light.  Room darkening is very helpful, though, when doing full video or tv type signal.  (We use the system for the men's group superbowl party each year.)  For regular worship we use a dual monitor set-up with one monitor that displays the projected image.
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Kent Clasen

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Re: Large Screen Video
« Reply #8 on: January 10, 2006, 09:38:06 am »

Hi Brian!

Are there higher power/lower cost 16:9 native projectors available now, or are you resizing native 4:3 projectors?  Is there a decrease in quality in using 16:9 mode on a native 4:3 projector?

Thanks for the info.
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Jon Bannan

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Re: Large Screen Video
« Reply #9 on: January 11, 2006, 10:15:07 pm »

Bob,

We are using a large 17x23 (I think that is the dimension) screen for our services and special events.  Our projector is currently located roughly 110-115ft in the back of our sanctuary.  We are using an Eiki 6500 lumen with a long throw lense successfully but as Bryan says light control is a huge factor.  We tend to keep our side blinds shut to cut out ambient cross light which helps tremendously.  We are using a 4:3 ratio.  Let me know if you have any questions.
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Re: Large Screen Video
« Reply #9 on: January 11, 2006, 10:15:07 pm »


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