Projector Question

Discussion in 'Displays' started by Jeff Welborn, Jan 13, 2004.

  1. Jeff Welborn

    Jeff Welborn Auditioning

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    Okay here's my question. Do front projectors (The X1 specifically) shoot out black, or is the black actually made from the dark of the room? Does that make any sense whatsoever?


    -Thanx
     
  2. Scott Dautel

    Scott Dautel Second Unit

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    Well there's a unique way of putting it....

    I'm not sure how a projector, based on a light source, could "shoot out black". So, if I understand your question correctly, the answer is that onscreen black is the projector attempting to "shoot nothing".

    All PJs (in the real physical world) however, at minimum project some amount of dark gray. Otherwise, that often quoted specification "contrast ratio" would be infinite (lumens white/zero).

    BTW ... even conventional televisions can only be as black as uncharged phosphors. If you turn off your TV in a pitch black room, you'll notice the screen glows for a short while as the phosphors are "discharging". Conventional CRT TV can't produce any better black that that "background glow"

    Scott

    Scott
     
  3. Jeff Welborn

    Jeff Welborn Auditioning

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    That's what I thought. Thank you for answering my incredibly stupid question.
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    A projector can only ADD light to the screen. Look at your screen in your viewing conditions. If you can see it, that's as black as it's ever going to get. The projector ADDs light to create colors and blacks. The black areas of the picture will *appear* darker when surrounded with bright objects.

    there is an inherent difference between bulb projectors, and CRT. They sort of work backwards if you will. A bulb projector (such as film, or a digital projector) has the bulb on full blast all the time. It then BLOCKS that light to prevent any light from going onto the screen, in order to "produce" black (i.e. not output any light). However, their ability to do this varies except for very expensive units. They leak light, thus even in pitch black scenes, they can't block ALL the light, and blacks look gray.

    CRT's natural state is off, totally black. The phosphors are then excited to create whites. Thus a CRT *can* emit absolutely no light. Properly calibrated such that you don't lose black-level shadow detail, there does tend to be a little bit of glow if you look through the lenses, but it should be pitch black on the screen if well calibrated.
     

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