Front Projection - Best Viewing Angle in Dedicated HT

Discussion in 'Archived Threads 2001-2004' started by Scott-C, Feb 15, 2002.

  1. Scott-C

    Scott-C Supporting Actor

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    I sometimes hear that the best place to sit in a commercial theater is in the vertical and horizontal center of the screen - meaning your line of sight is exactly to the center point of the screen.

    Does the same rule apply in a front projection-based home theater using either LCD or DLP technology? As you can see this is kind of an HT design question - I ask because I'm trying to determine how high on the wall to mount the screen as well as what height the viewer should be seated at. But, I see some websites where it looks like the "sweet spot seat" (which is in the front row) might yield a sightline below the vertical center of the screen, prompting me to ask this question.

    I know with rear projection TVs, viewing angle is very important so you're seeing the best picture, but I'm not sure if this holds true for front projection based on LCD and DLP technology.

    I'll probably have two rows of seats in my HT and at least one row (the back row) would be on a riser, but I'm not sure if the front row should be raised too.

    If it helps, assume a basement HT with at least 8' ceilings.

    Thanks in advance for your comments.
     
  2. RAF

    RAF Lead Actor

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    I know exactly what you are talking about regarding viewing angle with RPM's since my Pioneer Pro-75 RPM was one of the first units (back in 1990) to minimize light falloff on the sides, like most RPMs of the day did. The accomplished this by setting up the optics so that the light fall off occured in the vertical plane. In other words, the best picture could be seen sitting down, and not standing up or lying on the floor. But the good part was that people on the side of the room didn't lose any appreciable brightness.

    That said, I use a Stewart Studiotek 130 1.3 gain screen and it really makes no difference whether I am standing, sitting, lying down on the floor, up on a ladder, off to the side, whatever. To me the picture has uniform brightness. However, I would imagine that there are some screen designs where light fall off (and enhancement) is a function of location. Since my screen is about a unity gain (1.3 is close to 1) there is little effect at all. However, the high gain screens (2.5 and above) obviously do increase the light by reflections and, as such, are subject to location problems.

    I hope that some people with such screens will chime in here to offer their experiences.

    The bottom line is that the answer to your question appears to be -"Depends on the screen used."

    My 2 cents.
     
  3. Wes

    Wes Screenwriter

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    Well I would think with a 8' ceiling you will be limited to how high your first row and second row can be raised. I have an 7'8" ceiling and the front row is not raised, I have my second row 8" up. I really would not want the ceiling much lower (or the raised floor much higher) while on the riser. I do know what you are talking about, When we go to a theater we always sit dead center (I trained the wife to think that way also). But there you are talking about one big ass screen. In your theater you need to take the screen size, placement, riser height and distance into the equation. So I do not think you have the same situation of that of a real theater. When sitting on my second row my line of sight is just a couple inches under dead nuts center on the screen.

    Hope this helps!

    Wes
     
  4. Scott-C

    Scott-C Supporting Actor

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    Thanks guys for your comments. Both posts were very helpful. I have a few follow-up comments/questions for you:
    RAF: I would think for LCD and DLP technology, given the relative brightness of these projectors, that I would use a screen with a gain close to 1 as well. In fact, I'm not sure why, unless you were projecting onto a HUGE screen, you'd need a screen with gain in the "twos". I'm thinking of a screen about the same size as yours - 96" x 54" and 16x9 AR. Maybe 9' wide, but I won't know that until I have the dimensions for my proposed HT nailed down.
    Wes: I know what you mean, I trained my wife that the first place we look in a commercial theater is dead-center both horizontally and vertically. She really tries hard not to roll her eyes at me when I mention it.
    Your point about ceiling/riser height interaction is a good one. I'm doing a little planning for the future here, so I can't know for sure what the height will be, but of course ceiling height will become a factor and will help to dictate whether both rows are on a riser or just the back row like you did. My big concern was if the first row is lower than "dead-center" would that somehow yield a "lesser" theater experience in terms of picture quality, though it sounds like that is not the case for either you or RAF.
    RAF, Wes, and anyone else: Which seat in your theater is your "sweet spot" - what you perceive as the place to sit for best picture quality and acoustics. Is it in the first row or the center?
    Also, how high off the floor is the bottom of your screen?
     
  5. Wes

    Wes Screenwriter

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  6. RAF

    RAF Lead Actor

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  7. Scott-C

    Scott-C Supporting Actor

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    Wes: Thank you - that info helps in giving me a "reference point". The link that you provided me didn't work, however.
     
  8. Scott-C

    Scott-C Supporting Actor

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    Double post. Sorry!
     
  9. Wes

    Wes Screenwriter

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    How about this!
    [​IMG]
    I'm going to have to reshoot this shot looks like my mattes were not adjusted strait. Was borrowing a brotherinlaws digital camera and he was waiting impatiently for me to take some pics so I was rushed!
    Wes
     
  10. Scott-C

    Scott-C Supporting Actor

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    Wes, very nice. [​IMG] Thanks.
     
  11. RAF

    RAF Lead Actor

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  12. Scott-C

    Scott-C Supporting Actor

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    RAF, Thanks for the info on the Reclinermates. You're right - they're not evident at the Lane website, but a quick Google search brought up plenty of info on them. I like the little pull-out tray that looks to be suitable for glasses and cups rather than putting them on the top surface of the wood and risking stains/rings.
    Initially, I was thinking of getting those nifty "home theater recliners" with the cupholder built in, but lately I've had something of a change of heart. For one, the "standard" recliner/side table combination is probably cheaper than one of those HT recliners, so it fits into my "performance-to-price" ratio a little better. Second, the table affords me more space upon which to place drinks, snacks, my Pronto, etc. And, I like the idea of using the side table's storage area for remotes, and possibly some snacks for those mid-movie munchies. [​IMG]
    Thanks again to you and Wes for the help. This past weekend, with the help of HTF, I drew up a diagram of my "proposed HT/equipment room", and now it's time to start filling in the details, learning what I need to do and how to do it. Now comes the fun part!
     
  13. gregstaten

    gregstaten Supporting Actor

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    Just a few quick thoughts on some of things brought up in this thread:
    High Gain Screens:
    With the output of today's digital projectors, I'd agree that the high gain screen are not really necessary...if you fully control the light. These screens are sold into areas where a bright image is necessary even when a lot of light is on in the room - in other words, conference rooms and similar situations. As long as you can control the light, you're fine.
    As a point of reference, I just put a system in at work for our main classroom. It has a 12' wide 8x3 (dual projector) screen with a 1.3 gain. The projectors are three chip LCDs that output 1500 lumens each. If I turn on all the side lighting the image looks great. But, if I turn on the overhead florescent death lighting, the image looks like crap. To use the florescents and have a decent image would have meant a higher gain screen and/or higher lumen projectors.
    Home Theater Sweet Spots
    For a room the size of a home theater the sweet spot can be quite small - maybe only slightly larger than a single seat. So, my theater was designed so the front row center seat is exactly in the sweet spot. (Naturally, this will be *my* seat!) The L/R mains are to the sides of the 8' screen and are toed in slightly so the distance from the front row center seat to all three mains is exactly the same. I'll use delay timing to align the four surround speakers so they are also similarly "spaced".
    That said, I expect that the sound heard from the other seats will still be fantastic!
    Screen Offset from the Ceiling
    In my theater, the top of the screen is over a foot away from the actual ceiling, but is four inches below the bottom of the lighting trey. So, perceptually, it is nearly at the top of the celing. (The distance from the floor to the bottom of the lighting trey is a little under 7'.)
    -greg
     
  14. Wes

    Wes Screenwriter

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    Oops, wrong thread!

    Wes
     
  15. Scott-C

    Scott-C Supporting Actor

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    Greg,

    Thanks for your insights into high-gain screens.

    Other than speaker spacing and delay timing, what other things are you doing to calibrate the room to your "sweet spot"? What kind of surround speakers (bipole, dipole, monopole) are you using and how/where will you position them for optimal acoustics in the "sweet spot"? Are there other types of calibrations you're doing for it?
     
  16. gregstaten

    gregstaten Supporting Actor

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    Scott, I'm no expert on these things, but one way to calibrate the room overall is to do acoustic treatments. The walls are all being treated with both absorptive and diffusive panels. The front speakers are direct radiating and the side and rear surrounds are all dipoles. (I'm going with Triad LCR Golds for the fronts and Triad InWall Silver Surrounds for the surrounds.)

    Regarding placement of the sweet spot, that's how the room was designed by Dennis Erskine. I'm sure a LOT went into overall room dimensions to make the sweet spot be where it is.

    -greg
     

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