Strange Beam Angle

Discussion in 'Projectors & Screens' started by Azergoth, Mar 26, 2013.

  1. Azergoth Enthusiast

    Azergoth
    Joined:
    May 27, 2012
    Messages:
    23
    Likes Received:
    4
    Hi everyone!

    I have an Optoma projector at home and there is something odd about it. The light beam does not come through the center (see image) of the lens, but much higher. I'm not an expert, but this doesn't seem normal. I checked the user's manual but did not find something relevant at first gaze.

    photo.jpg
  2. Grador Audioholic Field Marshall

    Grador
    Joined:
    Feb 16, 2012
    Messages:
    1,579
    Likes Received:
    414
    Location:
    SoCal
    Poke around the menus, see if there's any image placement adjustments.
  3. lsiberian Audioholic Overlord

    lsiberian
    Joined:
    Nov 17, 2008
    Messages:
    12,196
    Likes Received:
    3,160
    Location:
    On A Bridge in Fort Worth
    That's why your throw is above your projector. It's by design. If you didn't angle it you would have your picture too low to be usable.
  4. Azergoth Enthusiast

    Azergoth
    Joined:
    May 27, 2012
    Messages:
    23
    Likes Received:
    4
    I dit it... The only thing I found is a way to mirror it vertically for hanging the projector on the ceiling.

    Well, actually, I have to tilt him down a lot...
    So you say it's absolutely normal? This is odd, they could just have tilted and moved the lens slightly. :s
  5. BMXTRIX Audioholic Spartan

    BMXTRIX
    Joined:
    Sep 16, 2004
    Messages:
    6,268
    Likes Received:
    1,595
    Location:
    Chantilly, VA
    They can't tilt the lens. That would introduce keystone or other distortion into the image. The shift upwards is called the image offset. Which specific model of projector do you have? You really should not be tilting your projector up or down as you will have to use keystone correction which degrades image quality. Instead, you should put the projector exactly where it needs to go. The range of offset of projectors is vastly different from model to model, but by example, the Optoma HD20, has an image offset of 16% of image height. So, for a 50" tall image, you have to put the projector about 8" below, or 8" above (if ceiling mounting) the desired image. I like projectors with less offset as you can be closer to the edge of the screen. The BenQ W1070 has very little lens offset. Likewise, there are projectors with optical lens shift which allows the lens elements to be moved to change the offset. This offset can be shifted not only up and down, but often left to right as well. Very cool feature.
  6. Azergoth Enthusiast

    Azergoth
    Joined:
    May 27, 2012
    Messages:
    23
    Likes Received:
    4
    It's an Optoma Themescene HD73...
  7. BMXTRIX Audioholic Spartan

    BMXTRIX
    Joined:
    Sep 16, 2004
    Messages:
    6,268
    Likes Received:
    1,595
    Location:
    Chantilly, VA
    The Optoma HD73..
    Optoma Projectors: Optoma HD73 DLP projector

    This projector has a 30% offset which is a ton for projectors. That means your 50" tall screen will require the projector to be 15" above/below the projected image height in a normal installation.

    More and more DLP projectors are getting away from this extreme offset. I've personally talked to some of them about how completely stupid it is to make a projector with that much offset. It only works for homes that have 9' ceilings!

    So, you get models like the new BenQ W1070 which have just a couple of inches of offset for that same 50" tall screen. Even better, it offers a bit of lens shift which means it can be adjusted a few inches more if needed.

    Sounds like your projector is operating typically and doing just what it is supposed to do. But, if you buy a new projector at some point and want it closer to the edge of the screen, then research before you buy so you get exactly what you want.
  8. Azergoth Enthusiast

    Azergoth
    Joined:
    May 27, 2012
    Messages:
    23
    Likes Received:
    4
    Thanks!
    Well that explains a lot.
    Actually, I didn't buy it but my father did, and I don't think he was aware of that feature. And when he bought it, he didn't know where the projector would be set. I actually took it because the projector was never used.
    Still, I find it a very strange feature :D

Share This Page

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
  • CEDIA