CurtPalme.com Home Theater Forum

[jkruger]

I am noticing too much stray light along the edges of my picture. I have a sony 1272 and it shines some extra light to the right and left of the screen, like there is some kind of reflection coming from somewhere in the projector and spilling out to the sides. What is this and how do I get rid of it? I also noticed a sort of halo around some white text on a black screen.

[Tim in Phoenix]

Hello

You may have noticed that projectors that have "Liquid Coupled" lenses are highly prized here. Such models usually have "LC" in the model number, such as Marquee 9500LC. LC lens setups are costlier to manufacture. A projector with Air Coupled optics may have a thin fluid filled space at the tube face for heat dissipation, but will have an air gap from there to the first lens element. Such an air gap allows reflection off the lens back to the tube face, and that bounce creates the halos.

The liquid coupled systems have a much larger fluid filled chamber contained at the tube face by a thin curved lens called a "C Element", and usually a rubber bellows arrangement also, so the tube face can be mechanically tilted relative to the lense to allow top/bottom and side/side focus. Some systems use cam rings for tilt, some use bolts.

The C element is concave and its' purpose is to contain the fluid in the shape of a lens. There is no air gap at the tube face, and the fluid is in effect the first lens. Bounce is all but eliminated, and halos are gone, and this setup gives the best possible contrast ratio. This means, on quality sources, that contrast ratio is higher, black and deep gray detail is seen, not hidden by bounced light however faint, and the image has more punch and three-dimensionality.


The pics are from a Marquee 9500LC Ultra we retubed:










.

[jkruger]

Does this mean its time to upgrade again? YAY!

[Tim in Phoenix]

[ecrabb]

Is the projector too close to the screen (did you maximize rasters... right to the edge of the tube face)? Do you have blanking set correctly?

What's your source?

I don't have that issue with my 1271.

SC

[jkruger]

I did the mechanical convergence mod, maxxed the rasters, then positioned it on a table to get the throw distance. Did some rough focus and convergence without changing the electronic controls before putting it up on the ceiling. the mount I made allowed me to raise/lower and tilt the pj to fill the screen with a squared up image resulting in the pj being very nearly perpendicular to the screen. ( Also a head-bonker for tall people) After doing focusing and convergence I pulled the lenses to check the rasters and they are within 1/8" of the edges on internal patterns and within 1/4" on the external input. I did have to do a rgb shift after hooking up the hd-a2 and hdfury to input 2, and have not checked the rasters after doing that. I'm going to pull the aluminum lens mounts and paint them flat black when the rain stops here.

Is there some kind of antireflective coating that can be applied to the lens/tube faces to reduce this?

[Sonynut]

You can paint the lens brackets with flat black paint(helps a little). The MAIN thing is to make sure not to run your CONTRAST any higher than 3-4 clicks below the point where the blue tube starts to bloom.. set this with a test pattwrn from your source.

....Anti-reflective coating on the tube glass might be nice. I wonder why AC projectors don't come with it?..

[jkruger]

Has anyone ever tried masking the lenses or tube faces? How about a flat black baffle between the two with a rectangular hole just the right size?

[Sonynut]

You can mask the tube glass above and below your raster(Ratios other than 4:3 anyway), but i doubt this will help the halo effect as the reflections are coming right from the active area anyhow.

[AnalogRocks]

You could also test tube masking with some black construction paper.

[AnalogRocks]

You could also test tube masking with some black construction paper.

[Mark_A_W]

Sounds like the Glycol level is low.

And/or the Blanking is not set.

[Fujifrontier]

imagine a little icon on the status display, "GLYCOL LOW"

[jkruger]

It's not the glycol level. I checked it when the pj was on the floor by turning it tube faces up and there is only a very small bubble in each tube. (1/4" diameter) It may be the blanking, I am a newbie and am not sure about how to set it. I may have opened it up when I maxxed the rasters. I don't recall reading about it in the installation manual. I'll read it again.

[deronmoped]

Masking will not help, any noticeable light around a bright image on a black background comes from the light trying to leave the glass and at that point a small percentage gets reflected back.

Deron.

[HD-DAVE]

HI,
Just a thought but have you considered/checked whether your stray light could be the result of stray light from the CRTS's reflecting off the ceiling or walls in your room ? If you have a white-cased pulldown or motorized screen it could also be a source of reflections...

Dave