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Does anyone know the acceptable tolerance for these effects? If you look at the side edges of the picture (on most I have seen in stores) there is a vertical band of shadow around 2cm (1inch) wide. This is especially noticeable on bright sequences.
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I have seen this on many sets including my Samsung 30" widescreen DTV. The effect appears to be visible even when using the component video input. I believe it is caused by signal reflections in the chain of things between the signal source (e.g. DVD player, etc.) and the DTV input.While I am not aware of any technical specifications for the acceptable intensity of the shadow image, in my experience, the intensity of the shadow image and the distance from the original image seems to depend on the video cables that I use. I tried several different kinds until I found that the Kimber PBJ (copper, not silver) Audio cables worked pretty well, with low noise and low level of reflections. What you may have not noticed also, is that there are several shadow images. One set may be so close to the orignal image, that you may have to look very closely to even see it. Another one is the one you see 2cm away.
If you haven't already done so, I would recommend trying different cables until you find the right one. And cost does not appear to be related to performance here, as far as I can tell.
Much appreciated my friend, I'll try swapping cables.
Do you also see on your's a band of darkness down each side (rather than a reflection). This is a darkened static banding on exactly the same position on each side of the image, about 1cm in from the side of the image. I have seen this same effect on televisions in shops. It is a bit irritating when you have seen it once!
I think you meant to say bands of darkness at 1mm (not 1 cm) on each side of the image. If so, what you are observing is the artifact of so called scan-velocity modulation "feature". This feature is supposed to make the images "look" sharper by utilizing an optical illusion effect (similar technique has been used on traditional photography for ages). This feature can be turned off on most digital TVs by accessing the service menu. If you really meant 1cm on each side of the image, I have no idea what's causing them.Also, I wouldn't be surprised if some DVDs and even over-the-air TV broadcasts pre-process the images with scan-velocity modulation type of treatment before even being sent to the TV or broadcast over the air.
I've got an engineer coming to look tomorrow so I'll let you know what he says. The effect almost looks like someone has smeared a black/shadowy band around 1cm wide, broader at the top and bottom, slightly curving in at the top an bottom. Measuring from the edge of the picture itself to the start of the banding is around half a centimetre. The effect shows on both 100Hz and progressive scan settings (the TV deinterlaces within the set if selected). One cannot switch off to normal 50Hz.
When I went to the local store saw this effect on at least half of the tube televisions I viewed. The best way to see it on my set is when watching bright panning sequences. Also by switching to DVD and not playing the DVD, this shows a plain blue background and the dark patchs are easy to see.
Very irritating once spotted! Thanks for your interest Jeechung.
That's strange. I have not noticed anything like that on my direct-view set (Samsung 30" widescreen), but I'll look more carefully and see if I notice something like it. I am very interested in finding out what your engineer has to say about it.
He looked and is now contacting Panasonic. I'll find out early next week.
I looked at my TV closely over the weekend and I did notice some sort of fringe lines on EITHER side of brigh images at a distance of about 5mm (~1/4 inch). This was not the SVM artifact that had I suspected earlier.I am not sure what's causing it, but it was noticable only when the brightness setting was very high. With the brightness setting turned down to optimum viewing, it was not visible. In any case, while I was puzzled, but it wasn't bothersome. What is still more visible was the SVM artifacts added by the TV broadcast (FOX baseball last night, for example)
The engineer is still consulting with Panasonic; I asked him to be sure what the tolerances for such things are. His conclusion, and that of others is that these are caused by the scanning coils. Note they curve in at the top and bottom, so they are slightly circular in their profile. They are most noticeable on 32inch and 36inch widescreen. He says once you have seen them once you will always see them so sorry for that.I agree with your observation about bright images. Even at low brightness settings though, with a light coloured background (a cream coloured wall, sky etc...) they are visible.
I'll let you know when we have the tolerances.
Panasonic say it's the extra fittings on the shadow mask behind the CRT, and is present on all of their widescreen Quintrix. I notices on other makes too, but Sony apparently have a different mounting method, so their imperffection runs horizontally top and bottom, but are smaller in dimension.
Such is life, it's still an exceptional television, especially on progressive scan!
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