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VW11HT Filter Madness

Discussion in 'Projectors, Screens & Video Processors' started by Dick Scratcher, Jul 4, 2002.

  1. Dick Scratcher

    Dick Scratcher
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    A thought occurred to me and, at the risk of sounding like a complete @rse, I'll have to let as many people know as possible even if it's just to confirm that I am completely mad.

    This whole contrast thing with LCD's appears to be relatively fixable with the use of a CC filter. OK, so its not perfect, but some guys are reporting fairly impressive results particularly when using one on the 11HT. Now I got to thinking, I use an 11 with a Stewart Grayhawk and from time to time people will comment that despite having a grey screen the colours are still OK and brilliant white still looks like brilliant white and not slightly grey as they were expecting. There is a very good reason why this happens but for simplicity lets just assume that some basic law of physics means that white still looks white when projected onto a grey screen.

    With me so far? Good! Now heres the thing. Why not use a grey filter in front of the lens as opposed to the 'pink' CC variety? Since colours won't be spoiled and white will still look like white there shouldn't be any obvious side effect. BUT, the additional grey tint should also go some way to blocking the light which bleeds through the LCD panels when reproducing blacks. Grey becomes dark grey and dark grey becomes black, you get my drift?

    So, am I a genius or am I mad?
     
  2. Dick Scratcher

    Dick Scratcher
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    Hang on, I might have missed something here. When white is projected onto a grey screen the image I see is 'reflected'. If I place a grey filter in front of the PJ lens the image will be 'refracted' first and 'reflected' second. Does the refraction disturb colour and white purity or is there no difference?
     
  3. Jeff

    Jeff
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    The grey filter is called an ND filter and are often used to cut the brightness down on projectors and improve blacks. The coloured filters are used for a reason, they allow you to max out the other colours and improve contrast.
     
  4. LV426

    LV426
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    A grey (ND) filter would decrease the light output of the PJ uniformly. Blacks would be blacker, and whites would be, well, err, less bright.

    The theory behind the colour filter idea is that, because of a combination of human colour perception and the colour of the lamp, the red LCD panel is "driven" to a higher level of contrast than the other two, ie there is some leeway in the blue and green panels.

    So, you add your pink filter, which cuts out some green and blue light without affecting the red light. This has the effect of reducing the intensity of blacks, and tinting every other shade pink. You then adjust the colour balance to increase the gain on the blue and green panels which restores the colour balance.

    Blacks remain blacker than they were. Whites are restored to the same intensity as they were before. In other words, you have increased your CONTRAST.
     
  5. Jonny1973

    Jonny1973
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    I tried watching my Panny PT-AE100 wearing sunglasses which should give a similar effect to using a grey filter.
     

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