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Discussion Starter · #1 ·
Projectorcentral.com mentioned this trick in the LT155 review. The review says "the pixel grid (of the LT155) can be rendered entirely invisible by placing the focus just a slight hair off perfect". Has anyone tried? How did it effect the sharpness of the image?


Looks like the LT155 is the lowest priced XGA LCD with MLA. Am I right?


-Isaac
 

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Quote:
Originally posted by shihtzu000:
... placing the focus just a slight hair off perfect".
Isaac,

that is the silliest thing you could do, isn't it? Why would you spend thousands of dollars for equipment to enjoy the extra sharpness of DVD and HDTV on large screens and then waste part of it again because of a design flaw of your FP? To me this just shows that LCD isn't the best choice for a Home Theater http://www.avsforum.com/ubb/biggrin.gif


Cheers

Christoph



[This message has been edited by clehner (edited 04-23-2001).]
 

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But it works.


A small amount of defocussing (less tha a pixel width) fills in the gaps and makes a smoother image without significant increase in softness except for HDTV text.



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Ken Elliott
 

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On the contrary side I find that I can completely eliminate the screendoor from my Sanyo 21N by a slight defocusing of the picture and I don't detect any degradation of the video signal. Do a search in the forum for other posts where people have tried this to get a range of opinions. See http://www.avsforum.com/ubb/Forum10/HTML/005858.html for a taste.


If you want to spend some bucks, you could try the IMX depixelating lens from Cygnus which some people have had success with. IMO, the defocusing works very well for me.



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John


[This message has been edited by Endymion (edited 04-23-2001).]
 

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Will that work for the Sony VPL-W400Q?
 

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I have a 21N (a few days old). I beleive the picture looks more film-like when it slightly de-focused. The screendoor becomes very difficult to see. (especially on indoor scenes).
 

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To Chlehner,

Screendoor, to me, is less of a problem than rainbow effect, that would drive me crazy. Don't want to start a war though, just responding to your post.

JOE
 

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Luis, you will not have to do this if your careful at picking your screen size in relation to your seating distance. This projector is unique in that the pixels are not lined up in perfect rows, the pixels are staggered, thus reducing the screen door effect dramatically, it looks very good even with the projectors lower pixel count. I wish more lcd panels were done with the staggered delta arrangement.

 

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Discussion Starter · #9 ·
Looks like with the LT155(XGA + MLA + slight defocusing), the pixels should approach the level of DLP projectors. Along with other benefits comes with LCD projectors, looks like LT155 is a more attractive choice compare with LP350 or DX3, in the $4k range. Agree?


Just wondering, does anyone do this slight defocusing trick to a DLP projector? (to further reduce screendoor effect) Or this only works with LCD projectors?


-Isaac
 

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I think there is a bit of a disconnect here about the nature of LCD WRT the issue of "sharpness".


LCD's are often favored for presentation purposes because the pixel structure actually lends a sense of sharpness. Text and presentation graphics take on an extra (but partially illusory) sense of sharpness due to the pixel structure.


This works against video, however, where the structure of the image is not the same. The evenness of the flow and texture is often more important that the strict ability to resolve detail.


That is why defocusing an LCD can improve its use in HT. It has to be done carefully, and will work better with some images than others of course. The sharpness you are losing is an illusion anyway.


Or--you can get a DLP and not have this problem! http://www.avsforum.com/ubb/smile.gif

 

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Actually, I do this too, and it does work excpetionally well. To the poster who asked why do this? If done correctly, it actually does NOT reduce actually sharpness, only percieved. Those black lines around the pixels trick you into believing there is greater sharpness than actually exists. If you defocus just to the point where the pixes move slightly to cover those lines, without overlapping, you lose NOTHING in terms of sharpness, but remove the screen door effect. In fact, this is EXACTLY what the Cygnus IMX lens does, just better than what can be done with regular focus.


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David Mendicino

Sharp xv-s55u (Don't laugh) :)
 

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This is actually one the first tricks I learned with my Davis clone DLP projector! There's also been a debate from previous threads on wether the IMX is worth the purchase compared to defocussing. Some declared both images were very similar, while others reported problems with the IMX (can't remember the specifics). Anyway, this was prior to the current IMX model, and I have no idea how the current model compares to the original. Cheers!


Gerald
 
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