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Lens shift? Keystone Correction??

Discussion in 'Projectors, Screens & Video Processors' started by PC_112, Apr 27, 2005.

  1. PC_112

    PC_112
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    Hello,

    If I have the Panasonic AE700 mounted on the ceiling (about 40cm from ceiling), and I project to a screen 3 meters away, how high should the image appear on the screen without getting any distortion?

    I've heard you can place the image almost anywhere you want with keystone correction, but that might have a negative effect on the image.

    Whats the lowest the image can appear without compromising PQ? Would that be 30cm from ceiling also? can it go lower? or it should be higher?

    I've heard that the AE700 has a 63% vertical lens shift range, but I don't know what that means exactly.
     
  2. FoxyMulder

    FoxyMulder
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    You should never need to use the keystone correction, there is a joystick control near the lens on this projector which can help you place your image on the screen its very handy and works a treat, remember to select the right settings in the menu or the image will be the wrong way when viewing.

    good luck.
     
  3. PJTX100

    PJTX100
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    Neither digital keystone nor optical lens shift offer flexibility to place the PJ anywhere you like. The best advice is always place the PJ as central to the screen as possible, especially in the horizontal plane. Before optical lens shift, keystone correction was the only(?) way to square the picture up if you were projecting vertically off centre. Now with optical lens shift there's far more flexibility to place the PJ, for example, high up.

    But you should view optical lens shift as a very useful fine adjustment tool, and avoid keystone correction altogether if possible.

    63% range probably means you can move the pic up to 63% the screen width or height. Again, the more optical lens shift you use the more chance of degrading the PQ eg uneven focus across the whole image...PJ
     
  4. PC_112

    PC_112
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    Thanks.

    However it seems to me that a vertical shift of 50% minimum is required when mounting the projector on the ceiling. Does this mean that if I mount it on the ceiling with 50%-55% vertical lens shift that I will get a decreased quality.
     
  5. PJTX100

    PJTX100
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    This is an interesting point.

    It depends on a few things probably, such as whether you can use an extension pole, and whether the PJ by default projects upwards (downwards for ceiling mount) or projects symmetrically (if that's the phrase).

    Best think to do is give it a try, I have my PJ snug to an exposed beam and I use optical lens shift to pull the pic down, seems to be fine.


    ..PJ :)
     
  6. PC_112

    PC_112
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    Anybody knows whats the default for Panasonic AE700?

    I will mount it almost 50cm from the ceiling.

    Would it be ok if the top of the projected image is about 220cm from the ground and the bottom of the image about 1 meter from the ground?

    Usually I will be watching by lying on a sofa bed, so I will be lower than usual, but I will not get any neck strain by looking higher.
     
  7. FoxyMulder

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    Heres the manual in PDF form it should give you all the info you ever need.

    ftp://ftp.panasonic.com/pub/Panasonic/Drivers/PBTS/manuals/OM_PT-AE700U.pdf

    My 106 inch screen is less than a metre from the ground and about 30cm from the top of the wall and takes up the entire wall, looks superb and i sit about 11 feet from the screen, no problems with any side effects at full size.
     

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