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skippyar
Joined: 22 May 2009
Posts: 108
Location: Bristol, UK
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| Posted: Sat Jun 13, 2009 6:33 pm Post subject: |
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Basically from your excellent diagram I can see where I'm creating so many unnecessary mistakes. This actually explains why I originally had to make such drastic adjustments to the CRTs settings.
To compensate for the slanted PJ screen plane I had to changed the >>Geometry>>LEFT-RIGHT E/W>>V Centerline skew>> setting to 'pulled' the top forward and slant the bottom backward. THEN I had to shift the >>Side Bow down from 50% to 56% to centralise it.
I always wondered why I had some settings dramatically offset from the 50% mark and this explains it.
I think you've probably cleared up all the questions had when installing this CRT. Cheers.
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Sat Jun 13, 2009 7:35 pm Post subject: |
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I suspect all those changes you made fixed the shape of the raster to compensate -- you probably have a pretty extremely-shaped raster as a result -- but they can't fix the optical issues.
It's up to you. If you can live with the focus problems, OK. If you can't, you know how to fix it.
But if that's really what's happening, I'm astonished your top & bottom aren't a lot MORE out of focus.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sun Jun 14, 2009 8:01 pm Post subject: |
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| ecrabb wrote: | | Boy, is that ever an understatement. All the sets of HD-8's I've had my hands on couldn't resolve anything much beyond 960x540p. When I was running 1080i, I never saw anything resembling scan lines on the screen, even though they were clearly visible on the tube faces (or even just looking into the lenses. They just won't focus well enough. SC |
that's not really true, this is my 8500AC with HD8's at 720P on a pretty squeezed raster, screen size of 92 x 48". MY photgraphy is awful, I can't even keep my thumb out of the pic, but you can clearly see scan lines at 720P. This is off the built in pluge pattern
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Sun Jun 14, 2009 8:18 pm Post subject: |
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HD-8's will resolve the higher scan rates, and can even do 1080P. It's just not the best lenses for it.
These were from my LOWLY 8500 that had HD-8 lenses (from the AVS screenshot thread)):
1920x1080P @ 72hz
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sun Jun 14, 2009 8:30 pm Post subject: |
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I need to get me some of them there test patterns.  trouble is i'm not sure how to get them on my screen. Can you just burn them onto a DVD and then slip it into a set-top BD player or is there some special "disc-formatting" involved.
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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Mon Jun 15, 2009 5:32 pm Post subject: |
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| draganm wrote: | | perisoft wrote: | | So here's another question: Has anybody checked to see if the lenses vary? It's not necessarily a foregone conclusion that they're all the same quality, is it? |
all HD8's are not equal. The older ones with the metal wing nut on top do not focus well at all. I don't know why, both say HD8 Rev. B but the older ones have aa silver sticker and newer ones Gold. Mind you these are all plastic. There were some glass HD8's but I've never had a set. |
Just got the last two HD8s via FedEx. I was originally going to check them in my luggage, as I picked them up in person while I was in LA on business, but the box only fit two. Since I had other stuff to ship back for work anyway, I threw the work stuff in the box with the lenses and FedEx'd the box instead of checking it, to make sure they didn't get lost - two lenses was about half the cost of three, to ship ground.
So, naturally, they delivered 'em to some random dude in a nearby town, and had to go retrieve the package... The FedEx lady I called spluttered that it can happen "when there's a lot of packages on the truck" ... A lot of packages? Isn't your JOB to deliver... A LOT OF PACKAGES? WTF?! Anyway...
So, I just checked them out since they're up in my office, along with me. They're gold label and wing nuts, so that's interesting!
Interestingly, the ones I got on the PJ had the knobs, and didn't seem to focus as well as the PT65s. Hmmmm....
I'll try to grab some photos of these things resolving 1080p. My 'stig still isn't optimal, so it's not SHARPsharp, but it's clearly visible. Props to jkruger for donating the lenses to the cause. I'm probably the only dude in the world who flew to LA to pick up HD8s because it was too expensive to ship them... 
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Mon Jun 15, 2009 7:04 pm Post subject: |
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| perisoft wrote: | | I'm probably the only dude in the world who flew to LA to pick up HD8s because it was too expensive to ship them... |
no, your the only dude in the world looking for hD8 lenses  . If I had known i would have sent you a set for the $25. cost of shipping. They're actually fairly light being all plastic.
I might have also mixed up the gold and silver label dates but most of the ones i have are newer? I have at least 2 dozen lying around here , mostly newer. I'll check tonight if I remember and take a pic side -by b-side.
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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Mon Jun 15, 2009 7:07 pm Post subject: |
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| draganm wrote: | | perisoft wrote: | | I'm probably the only dude in the world who flew to LA to pick up HD8s because it was too expensive to ship them... |
no, your the only dude in the world looking for hD8 lenses |
Well, that too.  I've got long-term plans including an LCD conversion, but I can't resist the idea of messing around more - and there are a couple of other reasons (including the method I had to use to mount the color filters) that may make HD8s superior in my specific case regardless of their resolving capacity vs. PT65s in normal operation.
This way, though, I got the company to pay the $25 to ship the other two instead of me! Muahahah! 
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skippyar
Joined: 22 May 2009
Posts: 108
Location: Bristol, UK
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| Posted: Sat Aug 29, 2009 1:54 am Post subject: |
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| garyfritz wrote: | Well, it's a little tough to see from your picture, but yes, it might be Scheimpflug issues. Especially where you have the projector mounted at an angle like that -- most projectors are designed to run "flat" and they have a built-in offset to display the image above the projector (with the PJ base flat on a table mount) or below the projector (with the PJ base flat on the ceiling for an upside-down ceiling mount). See e.g. p. 16 of the BG800 manual. If your focus is sharp in a band across the middle of the screen, but fuzzy at top & bottom, you've got a Scheimpflug problem.
Your projector is right-side-up but on the ceiling. If it was mounted "flat" it would be projecting up above the ceiling. By tilting up the rear to center the image onto your screen with the PJ "right-side-up" on the ceiling, you're working against the built-in vertical offset, and that WILL cause major Scheimpflug problems. The projector is designed to project to a flat vertical surface above the right-side-up PJ. The optics are aligned so the vertical screen is in the proper focal plane. By tilting the projector you've tilted the entire focal plane, and now it's focusing on a plane that is behind the screen for the top half, and in front of the screen on the bottom half. See the attached pic -- I took the setup image from the BG800 manual and rotated it the way you've rotated your projector.
It's easy to verify this. Get your center focus as sharp as possible. Now take an index card or other rigid piece of white paper. Hold it at the center of the screen, then move it out toward the projector. The image on the card should get blurrier as you move away from the sharp-focus point at the screen.
Now move the card down onto the bottom half of the screen. The image should be blurrier there. Now move the card out toward the screen again -- toward the proper focal plane as shown in the picture -- and see if the image on the card gets sharper as you move it out. If it does, then you definitely have a Scheimpflug problem.
The solution is "easy." "All" you have to do is flip your projector so it's upside down with its base parallel to the ceiling. Then your setup will be more like the picture on p. 16 of the manual, and you should have good focus across your vertical screen.
Honestly, though, if you're going to go to the trouble of pulling the projector off the ceiling, you really ought to consider replacing it while you have it down. Good EM-focus projectors are getting stupidly cheap. You'll be astonished at how much sharper and clearer the picture will be with a BG808 or Marquee 8500 or similar. It's not subtle. It's a night-and-day difference. |
I took your good advice and flipped the CRT over so it is now in the correct ceiling mounting fashion.
As you so rightly mentioned this has cleared up soooo many of the problems I was experiencing.
I now have a compressed spine though as a result of lifting it out of the housing to flip it over. Had to remove all 3 lenses to
help reduce the weight as I simply couldn't move it. (80KG)
Spent 8 hours setting up the lenses and parameters for both video and PC, but it was worth it.
Currently in the process of "refreshing" the lounge deco and cinema arrangement, will post some new photos in due course.
Paul.
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Sun Aug 30, 2009 3:32 pm Post subject: |
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Glad it worked out! And I hope your spine recovers!
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