CurtPalme.com Home Theater Forum

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

I couldn't think of a whitty Subject line. Laughing

Bottom line is, when electronic focus is optimal the all white screen is dingy (din-gee). However if I DEfocus it a bit electronically white is white again...but the pic is soft. ('Quee 8500. No vid chain mods)

The dingy off-white is what you'd expect from toasty tubes but even though there's 7200-ish hours on the 8500 chassis,(I'm ASSuming without additional info that the tubes have the same) the tubes look great. Just a hint of wear on the green and blue (as expected). Toasty tubes wouldn't produce a nice 100 IRE regardless of the focus setting so.....what am I looking at here?

Bert Randolph · Joined: 03 Jul 2007 Posts: 81 Location: Germany

Did you try defocusing only the blue tube?

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

**kal** · Posted: Fri Apr 03, 2009 1:49 pm Post subject:

Exactly right. Defocus blue. Blue output goes up a lot when you defocus it - much more so than the others. So when all 3 are perfectly focused, you're getting less blue light output as compared to red and green so the picture is yellowish.

You really need to read my Greyscale & Colour Calibration for Dummies guide. Smile

See: https://www.curtpalme.com/forum_archived/viewtopic.php@t=10457.html

Kal

akajester · Joined: 09 Jul 2008 Posts: 934 Location: Wisconsin

I would find a colorimeter too and go through that guide of Kal's. I went over to a friends house who has a marquee 8500 and his grayscale was WAY off. Even with the cheap spyder2 the improvement after about an hour of adjusting was night/day!

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Probably your white is just fine at lower IREs. As others have said, blue craps out when you drive it harder. Defocusing the blue (electrically, not optically) spreads out the blue spots and gets more phosphor working for you, so you can get more light output.

See this post for a more in-depth explanation.

csamos · Joined: 10 Jul 2008 Posts: 59 Location: Austin, TX

And don't be afraid to defocus blue a lot more than you think you should. A colorimeter should used to get an accurate grayscale, but you can at least improve it a lot by using a stair step pattern to eyeball it. A defocused blue tube won't affect the image as much as you think it will.

**kal** · Posted: Fri Apr 03, 2009 4:34 pm Post subject:

csamos · Joined: 10 Jul 2008 Posts: 59 Location: Austin, TX

I just checked, and my blue is set to 30 (0 to 100 scale, with 55 being perfect focus) right now. Here are the grayscale and gamma graphs from about 6 weeks ago. I've done a little tweaking since then, but I don't have any graphs saved since these.