AVS Forum banner

Status
Not open for further replies.
1 - 20 of 21 Posts

·
Registered
Joined
·
3,137 Posts
Discussion Starter · #1 ·
Hi all.


I'm giving my PJ and HTPC a major overhaul, and I was thinking that,

since we use binoculars and such for convergence, should we also

use them for focusing the lenses? Because, I didn't. I was wearing

my glasses, of course, but I just looked at the screen from the lenses,

while I turned them. It seemed that when you had the 'lock' on sharpness,

that was it.


So, it boils down to: Should I use binoculars/have my fianceé at the screen

or is it good enough looking from the lenses.


Thanks for your time...Again!


Nicholas
 

·
Registered
Joined
·
6,126 Posts
Do a search for the Guy Kuo holy focus thread...


Chip S.
 

·
Registered
Joined
·
198 Posts
Hi Nicholas


Not for me. I found I could not focus well looking at the screen from

the PJ lens. (in spite of the fact I can easily detect focus from behind

the PJ when I am watching a DVD or HDTV). I did better with a pair of

8X40 binoculars. Then I got out my old canon camcorder (regular 15X

zoom lens) and tripod, set it next to the PJ and aimed it at the center

of the cross hatch on the screen. I fed it's composite signal into a good

CGA monitor. Then I could easily see and adjust the lens focus. The only

hassle was re-aiming the camera each time I checked the center, corners

sides. I did not use it for convergence since I have a IR remote.


DH
 

·
Registered
Joined
·
3,137 Posts
Discussion Starter · #4 ·
Aha...could you get it much sharper that way? I mean, when you hit

nice focus, you have very little movement before it goes out again. Is

there a good difference?


Thanks,


Nicholas
 

·
Registered
Joined
·
198 Posts
Nicholas


Yes, You still have to deal with the flat zone at point of good focus.

I had to adjust "back and forward" across the in focus point. The

camcorder setup allow me to see it a lot better. I found that by

looking at the pixel shapes in the text was the best to focus on.

My ole buddy Walt, (aspec2 on avsforum) proposed the idea for

using a camcorder with zoom lens.


DH
 

·
Registered
Joined
·
3,137 Posts
Discussion Starter · #6 ·
Well, should I use a testgrid from AVIA(which will be at 864p) or an

internal at 15.6khz or so?


Could it also be that my anamorphic setting is making the image a

little blurry? I use squeeze in the PJ.


Nicholas
 

·
Registered
Joined
·
198 Posts
Nicholas


For Optical focus you can use any pattern, any source at any resolution

or format. It will be the same for all. For the other adjustments: electrical

focus, geometry, convergence and colors you need to set up with the

source(s) and resolution(s) you plan to use.


DH
 

·
Registered
Joined
·
3,137 Posts
Discussion Starter · #8 ·
Donald,


But I want to have a very fine testgrid. I think the grids from avia are

bulky looking. The line look smeared.


Thanks,


nicholas
 

·
Registered
Joined
·
198 Posts
Nicholas


My knowledge of a BG808 is limited. I think you can use the internal

patterns if you genlock to the source first. I too wanted a finer

line/dot/grid pattern for my marquee 8000. So I created a notepad

txt file with all "X". with a space between each X and on every other

row for a full screen. I found this was easier for me to do the corner,

side focus and scheimpflug focus. I still have that file, but I have since

used Autocad lite to create other images with standard lines (very thin)

and polylines of wider thickness. My SQUAREO.DWG file is similar to the

XFILE.TXT in layout with a small circle, a space, a square, a space and

so on, again on every other row. That one is easier for me to set the

H & V linearity than the internal grid pattern.


DH



DH
 

·
Registered
Joined
·
3,137 Posts
Discussion Starter · #10 ·
Thanks a lot!!


What about all you other guys?


Nicholas
 

·
Registered
Joined
·
2,606 Posts
Eyeball from PJ lens, and running back and forth. Wife helps some too saying "Its not in focus anymore." "You just had it." "I don't understand why your being so picky."


I definately like the text file with X's approach, and the camcorder approach. I can do the former, latter, well, no camcorder. :(
 

·
Registered
Joined
·
1,186 Posts
If you use the camcorder technique, you can actually use 2 pieces of paper taped to the camcorder monitor to see when the point of focus changes. I use 2 3x5 cards. One is cut in half and taped on three sides to the screen with the line I am trying to focus at the approximate center. I then insert the second card with a line drawn at the top. This card can slide lining up the drawn line to the edge of the focus line. As you move towards optimum the focus line will shrink. Slide the card to the line. When you go too far with the focus, the line will expand past the mark on the card. I do this because of the old eyes.
 

·
Registered
Joined
·
1,238 Posts
I'm having a real hard time getting my 1208 in sharp focus. I can get it pretty close by tweaking the HD-8 lenses, but it never 'snaps' into sharp focus and there seems to be major dead spots in those HD-8s. So I set them in the middle of where I detect the focus gets really bad.


Even after I get the optical focus as good as possible (spending like an hour going back and fourth between center and corners and using the 3x5 card technique), the image is still not sharp in any color when I move the 3.5 card back and fourth in various locations of the screen.


I figured the problem was therefore the beam focus, but playing with those controls back and fourth just takes me futher out of focus.


I'm running a [email protected] desktop from a MP-1 9700 Pro with 25' Canarie cables, and the 1208 has new tubes. So my source should be as clean as they come. Could the rest of the electronics in my '94 vintage BG1208 be 'tired' or am I just overlooking something?


It seems to me that by moving a 3x5 card back and fourth by the screen, I should be able to see what sharp focus looks like, but I don't see that at any point. I do see where its best, but at that point, things are still not super sharp. The test pattern I'm using is the full screen tiny clover leaf focus pattern that is part of the DisplayMate suite, and I cycle through the individual colors with this pattern and try to focus one lens at a time.


DVDs looks fantastic compared to my 60" RPTV, but I thought I'd be able to get a sharp desktop with my HTPC, especially at 1080x720 as opposed to 1440x960, which I know this projector is capable of.


Since I can't get a sharp optical focus, I haven't event messed with lens falpping yet, because I can't tell any difference when I try. Do I need to drop to 640x480 to get a sharp desktop?
 

·
Registered
Joined
·
594 Posts
Have you done astig and flare adjustements yet? On my Electrohome PJ it made a huge difference to the focus, especially on the desktop icons. I would also guess that the lense flapping (Scheimpflug) should also be part of the optical focus setup as it impacts focus also....
 

·
Registered
Joined
·
3,137 Posts
Discussion Starter · #15 ·
I solved the problem of my testgrid from AVIA being blurred. The AVIA

testgrid IS blurred. Now I use the Imtech ALIGN program, here I can

choose EVERYTHING. Try it.


Nicholas
 

·
Registered
Joined
·
52 Posts
No ones mentioned this yet so I thought that I would do it.


When recently redoing the lens flap and focus on my NEC 6pg Xtra, which is fed by a htpc, I use the nokia monitor test signals and ran my display at 640x480 with a very rough convergance. This was on an 80x45 screen from about 3m away. Focus was done using the nokia focus test signal and just staring with the eyes.


The test pattern gives you an almost all white screen with groups of lined boxes in each of the corners and the center. I found from using this I got the focus a LOT sharper than using the internal focus pattern, and I was able to get the focus spot on pretty all mechanically, with only electrical adjustment needed on the red, because I shut the case and then noticed it was not quite right.

Also when focusing I could see the scan lines when the focus was very good,a dn it was the sharpness of the scan lines that I used to adjust the focus.


I've attached a zip file containg the nokia test pattern program if you want to give it a try.


Chris.

 

nokia.zip 444.0712890625k . file
 

Attachments

·
Registered
Joined
·
198 Posts
Hello pclausen


You might give 800x600 a try.


I setup a 800x600 resolution in my Marquee 8000 for PC desktop use.

I found that I could get good focus and easy to read icons & text at 800

x600. Even after doing 'stig & flare to get a round dot, I could not read

the desktop well at 1024x768. At higher resolutions, the desktop text &

icons were too small and too indistinct to read. DVD and OTA HD do

look very good at higher resolutions (1024x768 & 1280x960).


Fantazia2. I downloaded and tried the Nokia NTEST program. It is very

good for focusing with a external source. Thanks for the attachment.



DH
 

·
Registered
Joined
·
1,238 Posts
When I raise the cover that exposes the CRTs, I see two shafts with grooves in them towards the very rear of each tube. These are the 2-pole stigmators, correct? It looks like if I turn them, they act like gears that fit into the surrounding rings and this will move them?


Are the 4-pole stigmators the single, rather large grey plastic ring with four flat fingers, about half way up the CRTs before you get to the deflection yokes? I'm only seeing a single plastic ring here that I can rotate around the CRT. Since I'm only seeing a single ring, I'm not sure how I can change the shape of the ovalness as opposed to just changing the direction of the axis.


DH, I'll try 800x600, thanks.
 

·
Premium Member
Joined
·
315 Posts
Question: Focusing the lenses: How did you do it?


Answer: Got it calibrated by William Phelps. :D
 

·
Registered
Joined
·
937 Posts
Quote:
Originally posted by fantazia2
No ones mentioned this yet so I thought that I would do it.


When recently redoing the lens flap and focus on my NEC 6pg Xtra...

Chris.
Chris, What did you actually do for the lens flapping. I have a PC6 Xtra as well and it was my understanding that akk you can do is put the little tabs in the specifierd location.


If you are loser to the screen then spec (in an effort to use more raster) would you use different tab positions?
 
1 - 20 of 21 Posts
Status
Not open for further replies.
Top