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Discussion Starter · #1 ·
I am about a hair's breathed from getting a G15, but before I jumped I'd like to get some input on using a ceiling-mounted DILA in conjunction with a 16:9 screen.


I am planning on have the DILA fill the 16:9 screen, essentially not using the top-most and bottom-most portion of the 4:3 panel, creating effectively a 1365x768 16:9 projector. However, with the DILA mounted (presumably upside down) to the ceiling and the top of the screen flush with the ceiling, I'll need to aim the DILA slightly up (toward the ceiling) to get the middle 16:9 portion of the DILA image positioned on the screen.


JVC recommends that the lens be on a horizontal plane that meets (at a perpendicular angle) the bottom of a 4:3 screen. I assume that this means that DILA would recommend aiming the lens to be perpendicular and somewhat below the bottom of a 16:9 screen.


Question #1: Will this approach cause "significant" keystoning or any other ill effects on image geometry and/or quality? Is there a different approach others have taken?


Question #2: Where can I get a ceiling mounting kit for a G15? What are my options? What are the costs?


Thanks in advance,

KEN


 

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Ken


I would try to keep the boresight on the D-ila perpendicular to the screen. Any offset will cause keystone problems and depending on the depth of field, focus issues.


To do this, move the projector higher or the screen lower. Or talk to Mark Hunter about Dilard PC software which will let you remap the signal inside the D-ILA to the pixel rows that correspond to the top of your screen.


I know that Vigatec won't move the image that much, but I think the Rock from TAW will. But I don't have one to confirm.
 

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Hi Ken,


You have the right idea, and it will work as you mentioned. However, with a little modification of your plan, it can work even better.


You could try to "land" the final image vertically on the screen by putting the picture in the center of the panel with careful calculations and the right zoom position. However, it would be much easier to line up the projector lens with the Top of the screen and use the top 1360x768 pixels (16:9 aspect ratio) and do all of your "cutting" from the bottom.


Aligning the projector with the top of the screen provides several benefits:
  • Easier positioning & zooming of the image initially.
  • Much less math to calculate where to mount the projector
  • Easier "upgrades" in the future (optical lens additions will be a piece of cake if you decide to go down that path).


For instance, in a ceiling mounted installation, you have the following scenario:
  • Projector mounted upside down.
  • Center of lens aligned with top of screen. If projector hangs 10" down from the ceiling, your screen is 10" down from the ceiling.
  • The top 768 lines are used (actually, they are the bottom 768 lines since the projector is upside-down). You have created your own high resolution, high fill-factor 16:9 projector.
  • Top-aligning the picture means that you can zoom in-and-out at will and the image will "snap" to the top of the screen without requiring any geometric calculations


Even if you don't plan to use the optical zoom (I don't), it sure is handy to get the picture the right size and position initially.


By the way, what scaler are you using? If it's an HTPC or the Rock, you will have some other options available.


I have a similar set up, so if you wish you can take a look at my D-ILA home theater installation .
 

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I have a G15 (actually a Dukane 9015, but it is the same projector), mounted upside down and a 110" 16x9 screen. I am using a Chief mount which I purchased from Irv Kelman who is a member here.


I strongly recommend that you follow the advice given here and keep the center of the DILA lens exactly parallel to the top of your screen. Make sure to loosen the "upside down" bolt on the G15, as that make sure that the optics work correctly when the projector is upside down.


I used a HTPC to set up a 1360x768 desktop using the "perfect DILA timings". I then used the zoom and positioning controls of the projector to perfectly position my Windows desktop on my 16x9 screen. IT WORKS GREAT. Maximize any application (including the DVD player - I use PowerDVD), and it fills the screen.


This setup also works perfectly for dScaler, since the same Windows desktop positioning applies to it as well.


The only extra work is to separately position the image for OTA HDTV and DirecTV since those come into Computer 2. But, again, the zoom and image positioning controls on the projector handled that as well.


Cheers,


Bernd
 

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Mark,

I also am on the verge of getting a G15. I currently have a 4/3 screen. I want to have the 16/9 image on the bottom of that screen and want to ceiling mount. Eventually (or sooner) I will go to a 16/9 screen. My confusion is:

Do I align the lens with the top of the 4/3 screen or where the top of the 16/9 screen will be?
 

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Hi Budd,


Do all of your aligning with where the 4:3 image would be...even if you are using the D-ILA as a 16:9 projector.
 

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Discussion Starter · #8 ·
Thanks for all of the good advice. I'll do as is recommended and trying shifting images vertically to use the top (actually bottom) of the 4:3 panel and keep the lens exactly perpendicular to the screen. I downloaded the D-ILA instruction manual last night... I assume I'll use the V.POS setting (It will let me shift a full 128 [or so] pixels?)


I will be building an HTPC for DVD and hopefully NTSC scaling, but I need to give ye olde wallet a rest for a while after springing for the G15. 8) Beside, I need the time to educate myself as I have not built a new computer in over five years and much has changed.


Is there a FAQ of sorts regarding HTPC connection to a D-ILA? For example, Bernd refers to "perfect DILA timings". For another, which video cards/software combinations will let me create a [email protected] desktop (I read somewhere that D-ILAs support 48Hz even though they are spec'ed to only go as low as 50Hz)? I know this stuff is in the HTPC section somewhere, but it can be like looking for a needle in a haystack.


Thanks again,

KEN
 

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Ken, you are in for some great fun! http://www.avsforum.com/ubb/biggrin.gif


I remember when I was in the same position. I started with buying my G11, using only a DVD player. It thought it was great! Then I used a progressive DVD player. The fun factor doubled. Finally, it was HTPC time. It can be quite overwhelming at times. Just take your time and follow examples of others and by all means, ask a lot of questions if you can't find your answers by searching. The very imformative post by xcel, Best in Class, was my PC bible for months while choosing and putting together my system. The DILA FAQ is here.


Make sure you budget into your cost factor the Dilard software. It'll do all the geometry modifications that you'll need, and a whole lot more. http://www.avsforum.com/ubb/smile.gif Have fun.


Chris



[This message has been edited by CCLAY (edited 06-05-2001).]
 
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