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Wally
Joined: 03 Nov 2006
Posts: 13
Location: The Netherlands
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| Posted: Mon May 12, 2008 6:53 pm Post subject: Grayscale Barco 800 Data: defocus on blue |
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Hi,
After grayscaling my Barco data 800 there is a bump in blue.
This can be corrected by de-focussing the blue tube.
On the focusblock, I can over- or underfocus it.
What is the correct option?
Wally
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|Sony 1251|Barco data 800|
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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Wally
Joined: 03 Nov 2006
Posts: 13
Location: The Netherlands
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| Posted: Mon May 12, 2008 7:01 pm Post subject: |
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Thanks.
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|Sony 1251|Barco data 800|
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kal
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Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon May 12, 2008 8:45 pm Post subject: |
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you defocus electronically to spread the electron beam over a larger area of phosphor thus exciting more phosphor increasing the blues output. since the most eyes cant focus on blue it wont be noticeable in the image. The only caveat is that if your cpc magnets are not set up properly the blue grid will move and you will have to re converge before moving on with the greyscale adjustments. You could leave it at that but setting up the CPC magnets for perfect dot size and placement will keep the grid in place over the entire ramping of the electronic focus control.
Athanasios
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Murillo
Joined: 30 Dec 2007
Posts: 113
Location: Sweden
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| Posted: Tue Sep 09, 2008 7:32 am Post subject: |
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| Nashou66 wrote: | you defocus electronically to spread the electron beam over a larger area of phosphor thus exciting more phosphor increasing the blues output. since the most eyes cant focus on blue it wont be noticeable in the image. The only caveat is that if your cpc magnets are not set up properly the blue grid will move and you will have to re converge before moving on with the greyscale adjustments. You could leave it at that but setting up the CPC magnets for perfect dot size and placement will keep the grid in place over the entire ramping of the electronic focus control.
Athanasios |
Do I just defocus midpoint or do I have to defocus everything? Is underfocusing above or below 50 and how much defocusing is needed?
Murillo
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kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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| Posted: Tue Sep 09, 2008 4:24 pm Post subject: |
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| Murillo wrote: | | Do I just defocus midpoint or do I have to defocus everything? |
On all CRT projectors you defocus electronically (not on the tubes) by defocusing the center. This defocuses everything.
On ES machines like the Barco 800 you do this by turning the blue focus pot inside the projector. On EM projectors like the Barco 808 you use the center focus menu option.
| Quote: | | Is underfocusing above or below 50 |
I don't know. Anyone?
| Quote: | | and how much defocusing is needed? |
Enough so that you can get a flat greyscale by flattening out the blue hump enough. There's no one right amount for everyone. Try a little, measure your greyscale, recalibrate, try some more, remeasure, etc.
Kal
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