Any LCD projector owners tried to place the focus slightly off to reduce screendoor? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 13 Old 04-23-2001, 07:21 AM - Thread Starter
Member
 
shihtzu000's Avatar
 
Join Date: Apr 2001
Posts: 45
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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
shihtzu000 is offline  
Sponsored Links
Advertisement
 
post #2 of 13 Old 04-23-2001, 07:42 AM
AVS Special Member
 
clehner's Avatar
 
Join Date: Feb 2000
Location: Berlin, Germany
Posts: 1,214
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
<font face="Verdana, Arial" size="2">Originally posted by shihtzu000:
... placing the focus just a slight hair off perfect". </font>
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).]

Regards
Christoph
*************
Contact via Public Profile
clehner is offline  
post #3 of 13 Old 04-23-2001, 07:56 AM
AVS Special Member
 
kelliot's Avatar
 
Join Date: May 2000
Location: Thousand Oaks, CA
Posts: 3,945
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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.


------------------
Ken Elliott

Ken Elliott
kelliot is offline  
post #4 of 13 Old 04-23-2001, 07:59 AM
Advanced Member
 
Endymion's Avatar
 
Join Date: Nov 2000
Location: Orange County, CA, USA
Posts: 513
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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.


------------------
John

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

John
Endymion is offline  
post #5 of 13 Old 04-23-2001, 10:47 AM
AVS Special Member
 
Luis Gabriel Gerena's Avatar
 
Join Date: Aug 2000
Location: Orem, Utah
Posts: 2,654
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Will that work for the Sony VPL-W400Q?

Mario Lemieux is GOD!
Go Pens!!!
Aguante Boca!!!
If dolphins are so smart...why do they live in igloos?
Luis Gabriel Gerena is offline  
post #6 of 13 Old 04-23-2001, 10:56 AM
Member
 
wvrich's Avatar
 
Join Date: Apr 2001
Location: Charleston, WV, USA
Posts: 163
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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).

Through man's sweat and God's love, beer came into the world...

- Saint Arnoldus
wvrich is offline  
post #7 of 13 Old 04-23-2001, 11:13 AM
Senior Member
 
jdang's Avatar
 
Join Date: Feb 2001
Location: san diego
Posts: 430
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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
jdang is offline  
post #8 of 13 Old 04-23-2001, 11:41 AM
AVS Special Member
 
Tom Bley's Avatar
 
Join Date: Jan 2001
Location: IL. USA
Posts: 2,229
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 20
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.

Tom Bley is offline  
post #9 of 13 Old 04-23-2001, 12:17 PM - Thread Starter
Member
 
shihtzu000's Avatar
 
Join Date: Apr 2001
Posts: 45
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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
shihtzu000 is offline  
post #10 of 13 Old 04-23-2001, 08:31 PM
AVS Special Member
 
rlsmith's Avatar
 
Join Date: Jan 2001
Location: Palo Alto, CA
Posts: 5,618
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
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

rlsmith is offline  
post #11 of 13 Old 04-23-2001, 09:12 PM
AVS Special Member
 
David Mendicino's Avatar
 
Join Date: Oct 2000
Posts: 1,195
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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.

------------------
David Mendicino
Sharp xv-s55u (Don't laugh) :)

David Mendicino
David Mendicino is offline  
post #12 of 13 Old 04-23-2001, 09:45 PM
Member
 
Richard Harnwell's Avatar
 
Join Date: Jul 2000
Location: Essex, England
Posts: 107
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Absolutely.

I find this almost essential for my Sony VW10HT (but then I do sit too close!)

Richard
Richard Harnwell is offline  
post #13 of 13 Old 04-24-2001, 01:45 AM
Senior Member
 
cutman0122's Avatar
 
Join Date: Apr 2001
Posts: 203
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
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
cutman0122 is offline  
Closed Thread Digital Hi-End Projectors - $3,000+ USD MSRP

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off