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Author Topic: video screen size  (Read 4699 times)

Mark Schneider

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video screen size
« on: May 24, 2007, 06:54:43 pm »

I am working with a church in the addition of a new video system to be installed in the sanctuary.  Currently they have none.  The room is a standard rectangle shape, about 60 feet wide, and about 90 feet from the screen location to the back row.  They just recieved thier first proposal back from an installer, and they have spec'ed two 60" plasma screens (one on each side).  Considering the distance from the screen to the back row, is this an appropriate and useable size?
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Kevin Maxwell AKA TheMAXX

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Re: video screen size
« Reply #1 on: May 24, 2007, 07:25:44 pm »

Mark Schneider wrote on Thu, 24 May 2007 18:54

I am working with a church in the addition of a new video system to be installed in the sanctuary.  Currently they have none.  The room is a standard rectangle shape, about 60 feet wide, and about 90 feet from the screen location to the back row.  They just recieved thier first proposal back from an installer, and they have spec'ed two 60" plasma screens (one on each side).  Considering the distance from the screen to the back row, is this an appropriate and useable size?


That is too small. The (2) industry standard size formula is the screen height should be either 1/6 or 1/8 the distance from the screen to the farthest seat. Assuming the standard 4 to 3 aspect ratio width to height. For a room that is 90feet to the back row the screen size should be either 20feet (wide) x 15feet (high) or 15feet (wide) x 11.25feet (high).

The screen material and the needed output of the projector are dependent on the lighting conditions.  

For more information see the link below. This is some good general information but some of it is specific to Da-lite screens since it is from their web site.

http://www.da-lite.com/products/selecting.php
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Kevin Maxwell
Freelance Audio Eng. QBE

Brad Weber

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Re: video screen size
« Reply #2 on: May 25, 2007, 02:22:01 pm »

Kevin Maxwell AKA TheMAXX wrote on Thu, 24 May 2007 19:25

The (2) industry standard size formula is the screen height should be either 1/6 or 1/8 the distance from the screen to the farthest seat. Assuming the standard 4 to 3 aspect ratio width to height. For a room that is 90feet to the back row the screen size should be either 20feet (wide) x 15feet (high) or 15feet (wide) x 11.25feet (high).

You forgot that the furthest viewer isn't on the centerline of the screen, they're also usually off to the side, so the distance can be greater.  Since two screen are mentioned, assume that the furthest viewer is roughly 15' off center for either screen if both screens are showing the same source, so not a big impact there with around 91' as a result.  But if you might have something different on each display then the furthest viewer is on the other side of the room and is around 45' off axis, now it's 101' to the furthest viewer which might make a difference.
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Brad Weber
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Derek Harkins

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Re: video screen size
« Reply #3 on: May 25, 2007, 03:05:14 pm »

Mark for the lack of a sales pitch and I am being careful as this is what I do for a living outside of the the church.  If you are looking at a 20 - 15' wide screen projecting in 4:3 you are looking at a powerhouse projector and you may need a lens depending on where you would like to mount the projector. The problem with most church settings is they think they can just use any projector to make an image on the screen.  The sad part is you cannot, Especially in churches where you have ambient light from windows, spots, chandeliers, etc. The screen surface should be matte white from DaLite as that is a 1.0 gain and works excellent.  Do you have a budget because the price of 2x60" plasmas may only be about equal to the cost of the lens.  Do you have a projector in mind?  if so here is a good link that will do the math for you..

  http://www.projectorcentral.com/projection-calculator-pro.cf m
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Derek Harkins
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Mark Schneider

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Re: video screen size
« Reply #4 on: May 25, 2007, 05:55:56 pm »

Thank you for your comments so far.  Currently, there is not a budget in place, since they have idea at whether the cost of an appropriate system would be $1,000, $10,000 or $100,000, they needed to find out a ballpark price to meet the needs they wanted.  Because of the layout of the room, any screens would have to be front projection, and have a distance of about 75' from the projector to the screens.  I know that would be costly, because of the need for long throw lenses.  That is why I think the initial proposal had the 60" screens instead.  Obviously that is much cheaper, but I feel that only would be useable for the front half of the sanctuary.  I am not sure the staff at the chuch understand how small a 60" screen really is from the back half.  They are just happy to finally have a video system, without realizing or accepting it's extreme limitations.  I don't want them to waste all that money on something that is only good for some of the audience, with the though that everyone will benefit.  I am very concerned about the 60" screen size.
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Brad Weber

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Re: video screen size
« Reply #5 on: May 25, 2007, 06:39:07 pm »

A critical point to consider with large format plasma or LCD panels is that for all practical purposes, everything out there is 16:9 format.  Because of this format a typical 60" display actually provides only about a 29" to 30" high image and it is the image height (or actually the related character height) that is the critical factor for viewing distance.  Depending on what is being displayed and how critical the viewing is, that typically represents anywhere from a 15' to 25' recommended viewing distance for a 60" 16:9 format display.  That may be great for a living room, conference room or even a small classroom, but it would apparently leave a lot of your congregation left out or squinting at the screens trying to see what's on them.
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Brad Weber
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Kevin Maxwell AKA TheMAXX

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Re: video screen size
« Reply #6 on: May 27, 2007, 11:57:38 pm »

Brad Weber wrote on Fri, 25 May 2007 14:22

Kevin Maxwell AKA TheMAXX wrote on Thu, 24 May 2007 19:25

The (2) industry standard size formula is the screen height should be either 1/6 or 1/8 the distance from the screen to the farthest seat. Assuming the standard 4 to 3 aspect ratio width to height. For a room that is 90feet to the back row the screen size should be either 20feet (wide) x 15feet (high) or 15feet (wide) x 11.25feet (high).

You forgot that the furthest viewer isn't on the centerline of the screen, they're also usually off to the side, so the distance can be greater.  Since two screen are mentioned, assume that the furthest viewer is roughly 15' off center for either screen if both screens are showing the same source, so not a big impact there with around 91' as a result.  But if you might have something different on each display then the furthest viewer is on the other side of the room and is around 45' off axis, now it's 101' to the furthest viewer which might make a difference.


No I didn’t forget.

Most of the posts from you seem to indicate that you are knowledgeable so I am not addressing that at this point. I am not sure how to respond to your post, while you are technically correct you are practically wrong. I don’t post as much as some people because it would take too long to properly answer some questions. In this case I gave basic information with basic answers and a link to more detailed data. I make my living at this, as it seems you do too. We do this web thing in an effort to help a little bit. And to get help a little bit.  

Just from what the original posted has written one can tell that they will be lucky if they get one projector with the proper capabilities and one screen of a size big enough to be seen well towards the rear of the room. They are not to the level that will be displaying 2 different images on multiple screens. And most churches for a room that size will probably not even use the larger of the 2 sizes that I mentioned. So the information I gave and the link is more then enough to answer the question. And the link helps to reinforce that this isn’t just my opinion but what the manufactures of projection screens recommend. This gives the original poster the ability to take the manufacturers data to the powers that be and show them that it is not just the opinion of some unknown poster on the web as to what is proper for their situation.

So based on that the difference between 90feet in my equation and 91feet and even 101feet is inconsequential.

Neither of us is going to in their reply write the book that would be necessary to answer all of the questions that someone like the original poster should be asking. The only reason that we don’t use the line of “hire a professional” is we know they probably wont. We use that line when it comes to issues when life and limb are at risk like electrical or rigging questions.

As the saying goes “with all due respect” You sir are nit picking. So how much respect is due?

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Kevin Maxwell
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Brad Weber

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Re: video screen size
« Reply #7 on: May 29, 2007, 02:11:12 pm »

Kevin,

I am not sure what you apparently took such offense with or why.  My comment was not nit picking, the effect of the furthest viewer being off axis both horizontally and vertically effect can be a factor in the furthest viewer distance, especially in fan shaped or wide and shallow rooms with high mounted projection screens that are common for contemporary churches.  And since having two displays was presented in the original post, you can have get noticeable differences in the recommended screen size depending on whether they plan to display the same source on both screens or potentially two different sources.  Based on years of practical experience I have found that these issues can be significant and are often overlooked.  Saying that this is "practically wrong" certainly conflicts with my experience.

Now that they are out there, I feel that some of your comments need to be addressed.

Quote:

Just from what the original posted has written one can tell that they will be lucky if they get one projector with the proper capabilities and one screen of a size big enough to be seen well towards the rear of the room. They are not to the level that will be displaying 2 different images on multiple screens.

Perhaps you missed the follow up post that noted:
Quote:

Currently, there is not a budget in place, since they have idea at whether the cost of an appropriate system would be $1,000, $10,000 or $100,000, they needed to find out a ballpark price to meet the needs they wanted.

So it seems to be a big assumption that it is budget and not having two displays or two different images that would be the deciding factor here.


Quote:

So the information I gave and the link is more then enough to answer the question. And the link helps to reinforce that this isn’t just my opinion but what the manufactures of projection screens recommend. This gives the original poster the ability to take the manufacturers data to the powers that be and show them that it is not just the opinion of some unknown poster on the web as to what is proper for their situation.

If you read that information closely you would note that it is filled with disclaimers about the recommendations working in most situations and being only guidelines.  That information is useful, but it is really more aimed at general classroom and conference room type applications.

Although not identified, the 1/6 the furthest viewer guideline for screen height is based on computer graphics and PowerPoint type applications, which may or may not be applicable for a church setting.  The 1/8 recommendation is based on motion video but many people have found that for I-Mag and very large font text, as small as 1/10 may work.  These guidelines are also based greatly on a typical long and relatively narrow room like a classroom.  This may fit a traditional church, but a wide or fan shaped church may need special consideration.  The point is not that you need to know everything, but rather that people need to realize some of the limitations to such general guidelines.


Quote:

So based on that the difference between 90feet in my equation and 91feet and even 101feet is inconsequential.

Why do you say that?  What would define 'consequential'?  At 1/6 you are talking a 15'x20' (300 sq. ft.) screen versus a 16-10"x22-5" (378 sq. ft.) screen, that's over a 25% increase in screen area and doesn't seem inconsequential.


Quote:

Neither of us is going to in their reply write the book that would be necessary to answer all of the questions that someone like the original poster should be asking. The only reason that we don’t use the line of “hire a professional” is we know they probably wont. We use that line when it comes to issues when life and limb are at risk like electrical or rigging questions.

I would always suggest hiring a professional whenever possible.  The simple guidelines like you referenced may provide a good general answer, but when professionals look at a screen for a facility like a church they should go well beyond these simple guidelines.  Their considerations would likely include the seating areas and their relations to the screen(s), the screen location(s) and factors such as being on angled walls, the ambient lighting control, the screen material and it's effect on viewing angles, how the resulting viewing area relates the the viewers, and even things like the vertical angle from the closest viewer to the top of the screen and in some cases, the lens being used on the projector.  And also factors such as ceiling heights, locations of air vents and lights, protruding millwork and so on.  These are all considerations that may affect the screen location, size and projection surface.

I am not trying to answer every question or give all the answers, but rather just to identify that there are indeed many practical considerations other than just the depth of the room that can affect what is a viable screen size and that many of these are often overlooked.  The important thing is in identifying when these considerations may apply to a project and may indeed justify involving a qualified professional.


Quote:

As the saying goes “with all due respect” You sir are nit picking. So how much respect is due?

Obviously, I disagree.  I'll just leave it at that.
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Brad Weber
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Brian Kent Tennyson

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Re: video screen size
« Reply #8 on: May 30, 2007, 01:01:39 pm »

In a church setting you can usually get away with a 12:1 or even a 15:1 LFV (least favorable viewer) to screen height ratio. Text height control is the main factor. You will be sacrificing detail in motion video images.

Where are your 60" plasmas going to be mounted? What is your budget?

From the front of the room the 60" will give you a ratio of 32:1. For an idea of what this would look like, find a 18-20" computer monitor and stand 32 feet away from it. Can you read it? Probably not.
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Brian Kent Tennyson

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Re: video screen size
« Reply #9 on: May 30, 2007, 01:12:05 pm »

Furthermore (i.e. I finally read the other replies in detail), if two 60" plasmas are your contractors recommendations for "best solution without a budget" RUN (don't walk) to another reputable contractor or consultant.

What was his recommendation for the sound system, a pair of 10" shelf speakers? That would be the sound reinforcement equivalently.
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Re: video screen size
« Reply #9 on: May 30, 2007, 01:12:05 pm »


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