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Barco Higher than recomended

Discussion in 'Projectors, Screens & Video Processors' started by m0v1em4n, Oct 19, 2001.

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  1. m0v1em4n

    m0v1em4n
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    Hi All

    If I was to install my Barco 708 higher above the screen than recommended in the barco lens programme and angled it down towards the screen would it cause any problems

    Steve
     
  2. Roland @ B4

    Roland @ B4
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    Yes
    That is why Barco went to so much trouble to write the program so you know what the limits are.

    By increasing the angle beyond the maximum (and IMHO I belive the lens programm allows too much for critical viewing already) you will
    Age the tubes significently quicker.
    Have to adjust the convergence more often due to the extra stresses that this causes.
    You will definitly need spacers to adjust for focus but you may not be able to achieve proper focus.
    If ceiling mounting the projector the top of the image will be brighter and sharper because you are using less phospher at the bottom.

    If you do go to a steep projection angle and are using a 16x9 screen you should not attempt to do 4x3 within that aspect the amount of energy that you could use in that small area could burn the tubes very easily.

    The Barco 708 has very significant keystone adjustments adjustments and whilst it would DO what you are suggesting. I would be very careful.
     
  3. m0v1em4n

    m0v1em4n
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    Hi Roland,
    Can you conferm that negative ceiling distance would be above the top of the screen so for my 71" screen PD would be 97.3" and A would be -6.3 above screen
    Steve :confused:
     
  4. uncle eric

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    Steve/Roland,
    Basicly, if your screen is mounted at the top of your wall (were your ceiling begins) and you ceiling mount your Barco (any model) at the correct distance away, acording to the Barco lens program you will always get a negative distance.
    The only way you WONT get a negative ceiling distance is if you mount your screen fairly low (which not many people like) or if you hang your projector around a foot lower than your ceiling (great if you are a head banger).
    Possibly the best compromise is to tilt a little (up to 5 degrees should be ok)

    Eric
     
  5. m0v1em4n

    m0v1em4n
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    Any extra height would be nice, noticed that if i went for a bigger 79" screen, but reduce the height of the screen to 40", this would give me a negative ceiling of 8" in the lens program, any ideas why normal screen height would have been 44", would not mind go up to 79" width screen if I could reduce the screen height to 40"

    Steve
     
  6. Roland @ B4

    Roland @ B4
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    Steve
    The figures you have quoted are for a standard 16x9 installation. You can tilt the projector down by an extra 2 degrees I would suggest not any more because of reasons I highlighted above. (I thought from the wording of your post you were already on the recomended maximum)

    An extra 2 degress would give you the 10 inches from top of screen to highest part of projector. You would be able to sqeese a bit more out of the vertical shift so I would have thought 12 inches woud be safe.

    In the lens program it allows you to enter the extra angle just add it to the 10.5 degress which is set.

    You will still have to shim out the lenses to get proper focus.
     
  7. m0v1em4n

    m0v1em4n
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    Thanks Roland,
    Decided to go for a 71" width which according to the lens program gives me 39.9 screen height and at a 12.5 angle that would give me approx 10" at the front of PJ and 10.8 at the back,
    I know I am chopping and changing but need to get it right, you have seem pictures of my Cinema room the roof is low and don't wasn’t a sore head :D, but the extra height would make all the difference.
    How do you mean shim the lenses are there special shims for this and would i be able to carry it out.

    Thanks for all your help so far.

    By the way Roland did you get that letter hope all was OK!

    Steve Morris
     
  8. Roland @ B4

    Roland @ B4
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    The shims are special washers that space the lenses correctly for a non standard projection angles. Sto that the top and bottom is correctly focused.

    Letter arrived and is fine thanks.
     
  9. m0v1em4n

    m0v1em4n
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    Hi Roland,
    Would barco still stock these, any idea of cost,
    So basically if i angle my PJ more than the 10.5 used in the lens program i would need shims,
    Steve
     
  10. Roland @ B4

    Roland @ B4
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    They come as standard with the projectors when new.

    The only special thing about them is the size but I have used a multitude of different things in the past. (but don't tell any one I've done an inastallation for)

    Calculating what they should be and what happens in practice is totally different.

    If I did the instal for you they would be free if you want me to order these shouldn't be more than a few pounds.
     
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