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Projector Mount Calculations

Discussion in 'Projectors, Screens & Video Processors' started by pj-uk, Sep 9, 2005.

  1. pj-uk

    pj-uk
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    I'm just a few days away from ordering up the Z3 and need someone to run over these calculations for a mount.

    My ceilings are 3.3m high :( and I want to ceiling mount the projector so it looks like I'm going to need an extension for the mount.

    I can accomodate a throw distance of about 3m giving me a diagonal screen size of 230cm (90") and height 100cm (39"). I understand that the Z3 has a vertical shift of 100% so from my calculations I can move the image down by ~100cm.

    So if the projector was mounted flush with the ceiling (parallel to the floor) I could get the bottom of the image down from 2.7m (3.3m-0.5m) down to 1.7m using the lens shift.

    I would like the screen to be around 130cm from the floor (a further 40cm) so the only options I think are:

    a) get a mount that has a drop of around 30-40cm and use ~100% vertical lens shift.
    b) get a ceiling mount with no drop and angle the projector and use keystone correction with no lens shift (would need to angle the PJ by 30°).
    c) get a ceiling mount with a drop of around 30-40cm AND angle the projector using both keystone and lens shift.

    What would be the best option?

    The second question is by using almost 100% of the vertical lens shift will there be a vast drop in quality?

    Thanks for all the help!
     
  2. PJTX100

    PJTX100
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    Using lots of optical lens shift can have side effects such as uneven focus. Having said that I'd rather have lots of optical lens shift rather than a combination with digital keystone which basically throws away resolution and introduces a whole new raft of digital processing...PJ :)
     
  3. pj-uk

    pj-uk
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    So my best option would be to get a nice long ceiling mount :)

    Do my calculations seem about right? If so I'll be needing something in the range of about 50cm and about 60-70% lens shift (giving me a total of around 130cm vertical shift)

    Lastly, where would the cheapest place be to get such a mount (I've checked on fleabay and all the mounts appear to be fixed flush with the ceiling)

    Thanks again!
     
  4. PJTX100

    PJTX100
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  5. IronGiant

    IronGiant
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    Wow, 3.3m, mine is 7'6", I have the opposite problem! Fortunately I could mount on a back wall and get round it that way. The least correction you can get away with will get you the best picture. In your situation I'd definitely think about a very long extension tube to minimise lens shift and not use keystone at all if I could get away with it, as PJTX100 said.

    Dave
     

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