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Discussion Starter · #1 ·
Over in the DWIN TV3 OWNERS THREAD, we've been having what some would regard as a controversial discussion about "Ghosts".


A couple of us (2) are seeing an artifact (or phenomenon
) on bright white images on dark backgrounds.


I've personally seen it on four different projectors (all TV3's) and there is one other member who sees it too. I've also heard an unverifiable report of this occurring on the HD2 Marantz.


Attached is a rendering, (I haven't been able to photograph it yet - which is fueling the controversy, but I will continue to try), of this artifact / phenomenon that I am experiencing.


Has anyone else noticed anything like this, or are we "In Search of" Elvis?
 

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Here's a long shot. Are you perhaps using a hush box with a glass window ? Reflections from the glass to screen along some secondary path can cause such ghosting. I have seen this happen with a slide projector.


Presumably the same sort of thing can also happen within the projector itself.


Brent
 

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Discussion Starter · #3 ·
Nope, no hush box.
 

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Quote:
I've personally seen it on four different projectors (all TV3's) and there is one other member who sees it too. I've also heard an unverifiable report of this occurring on the HD2 Marantz.
I think it is the ghost of HD1. It was mad that it got axed so fast that it started appearing in the HD2 and soon to come out HD3 projectors. I have a HD1 Marantz and of course I don't have it. http://www.avsforum.com/avs-vb/images/smilies/wink.gif


Mike
 

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Intersting.

Have you tried different cables or source equipment.

Anyway to set the projector to a black background with no source plugged in and pull up a menu to see if its there.
 

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Discussion Starter · #6 ·
Unfortunatly, the TV3 displays a white field when there's no source connected, however, I can tell you that it is on the menu.


It's present on component and DVI DSS, as well as DVI DVD.
 

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A long exposure time (several seconds) should capture any visible artifact on the screen. I'm no photographer, so I'm can't give specific recommendations on film speed, shutter speed, etc. Just a general comment that, with the proper camera, it shouldn't be too hard to grab a picture of it.
 

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At this point I think you've covered all possibilities and all you can do is wait for a response from other Dwin TV3 owners to see if they have the same thing.
 

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If your simulation is accurate it looks like a video double scan or electronic "echo" artifact. If it's the same on DVI and analog inputs that's a hard one to figure.

I've seen it before with faulty component and 15 pin analog cables and again saw it with wrong timing setting's on digital DVI monitors.

It sure sound's to be internal (in the pj) from what you've said.


One question, is the "echo" stable or does it "flicker" for lack of another word ?
 

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Has anybody tried to zoom in and out to see if it might be an imperfection in the lens?
 

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I agree with the poster suggesting a problem with the lens.


I have seen similar ghosting in a slide projector lens a few years back, and the 1st Panamorph PSO I received also had a similar ghosting which was attributed to a production problem.
 

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Discussion Starter · #13 ·
Jimmy - it's stable, no flicker. Can you elaborate on the DVI timing issue? There's a setting in the advanced menu called "Index Delay", but our best guess right now is that it's a color wheel timing offset.


I think optics is the culprit as well. The problem seems to be more previlant towards the bottom of the screen where the angle that the light is passing through the lens is at it's greatest.
 

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For those not following the Dwin TV3 thread, there are a couple photos posted of this Ghost and the one I posted was of the ghost with the brightness boosted to the point is was obvious on your computer screen.


I believe those getting this ghost image are using something other than a matte white screen or greyhawk. ie a screen with gain. This is just one of many hunches that I haven't ruled out because so far not enough information is logged.


FWIW- I have a TV3 with matte white screen and have photographically documented no such ghost artifact. I may try to borrow a screen sample of a screen with gain this weekend if I get some time and the dealer is cooperative to run some tests.


BTW- You'll notice in the real image photo the Ghost almost resembles a series of lens flares off each of the white pixels of the primary image.


What ever is causing this, more than one person has created the conditions to see it.
 

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Don, if your projector isn't having a problem how can you document otherwise? :D Most assume the projector isn't having a problem, and if it is having a problem then forthcoming documentation is a expected.
 

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I took the picture and have the other DWIN with the same ghosting problem on a StudioTek 130. I have a 2' x 2' sample of a Stewart Greyhawk that I projected onto to see if it was the white 1.3 gain screen. I believe that is a negative gain screen material and I still saw the ghosting above the letters, though not as bright.
 

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Discussion Starter · #19 ·
Well, that seems to rule out the screen material.
 

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While not saying it is your lens for sure ... I can replicate what you see quite easily.


I have a CC40 filter that I don't use all the time. Its just a 4x4 square. If I'm lazy (often), I'll just literally tape it onto the projector lens-housing. If I only tape the top, it doesn't lie flush to the housing (it flaps out a bit at the bottom).


When I have the above .. I see ghosting on text. Its most obvious on movie-credits at the bottom of the screen. As was suggested earlier, probably some refraction through the filter creating different light path (not sure).


If you had some problems within the lens (small separation between elements??) I could envision something similar, just not nearly as obvious as what I see.


probably doesn't help .. but there it is.


Ron
 
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