Does noise in a projectors image decrease as the movie goes on?

Discussion in 'Displays' started by David Payne, Jul 3, 2006.

  1. David Payne

    David Payne Stunt Coordinator

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    Or is it my imagination? I've had the BENQ PE7700 for over a week now, and I was sure that the reason I wasn't noticing noise after the first 10 minutes of a movie was because I'd just got used to it. But I'm starting to wonder if the projectors noise reducer continually improves the image as the movie goes on. Just now, I watched a film, and started to have a really good look at the picture, and there was nowhere near the same level of noise as I could see at the beginning!
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    There shouldn't be any reason for this, unless for some reason the source is like this.
     
  3. David Payne

    David Payne Stunt Coordinator

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    Yeah, you're probably right. I think it's most likely down to me getting accustomed to fairly noisy sources (watched a few old DVD's lately!). But I did wonder whether there was some sort of ongoing adaptive process that that was doing something.
     
  4. David Payne

    David Payne Stunt Coordinator

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    Or could it be that the projector needs a good 10 minutes to warm up? I've tried switching it on a while before I actually try to watch the movie, and I think I'm also seeing less noise.
     
  5. Leo Kerr

    Leo Kerr Screenwriter

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    Define "noise."

    Projector lamps do have a warm-up time. While they're warming up, especially as the lamps get older, they do exhibit some ugly symptoms. Unstable and wandering arcs can cause the image brightness to flicker and "wander" in the image area. (Not that the image walks, but that the brightness will be uneven, with the hotspot wandering around in the center area of the image.)

    Second to that, I'd say whatever you're seeing, you're getting used to it.

    Leo
     
  6. David Payne

    David Payne Stunt Coordinator

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    ^Hmm, not sure how to describe what it actually looks like. Although, I know from past experience that what I'm seeing is often attributed to noise. But you could be right in suggesting that the cause is elsewhere. My projector is actually only a few weeks old. In fact I'm new to projectors altogether, which is why I'm having trouble getting the picture how I like it! At any rate, I'm confinced it was just a warm up issue. I've started switching it on 10 minutes beforehand, and the problems gone.
     
  7. Leo Kerr

    Leo Kerr Screenwriter

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    then there may possibly be something wonky about your unit. Are you running analog or digital connections (dvi/hdmi?) I don't know what that unit has, but its not unheard of to have something wonky on an analog input board, or, worse, the formatter board (unless they're the same board.) Bad capacitor? Transistor? Not an easy thing to tell...

    Leo
     
  8. David Payne

    David Payne Stunt Coordinator

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    Unfortunately I'm only using S-Video, and will be until I upgrade my player to one that has an HDMI output. But I'm not bothered too much by it. As I said the problem doesn't seem to be there now that I've stopped hitting play as soon as the projector comes on! When I have some time I'll sit down and have a good look at it, and see if I can track down what I was seeing. I'm still open to the possibility that it was all in my head! [​IMG]
     
  9. Don Solosan

    Don Solosan Supporting Actor

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    Well, an easy way to tell is to put on something new that won't have print damage, or something digital like a Pixar movie. If you're seeing noise, then it's not the source.

    The first thing I thought of when you said you were watching older movies is that if they used prints for the transfers, the heads and tails of reels tend to get the most wear and that's where you see dirt and stuff. But then you should see the noise reappearing with the reel changes...
     
  10. ChrisWiggles

    ChrisWiggles Producer

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    It's really hard to tell unless you describe what (specifically) you were looking at, and what the noise looks like. The kinds of things that fit under the category of 'noise' are many, so it's really impossible to give any guidance unless you describe thoroughly what you're seeing, when you're seeing it (specifically) and also when or where you may not be seeing it. If you pause the image, does the noise go away, or does it remain? Is the noise pattern frozen in place when paused? Is it temporal in nature? etc.

    Also, I would not necessarily just assume that an animated title is 'noise-free.' There are many limitations that can appear in animated titles as well that might be described as 'noise.'
     
  11. Paul_Scott

    Paul_Scott Lead Actor

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    I seen several people comment that the Benq 8720 needs about 10 hrs on the bulb before the 'noise' disappears. I've not heard of this phenomenon before, but it could be related to what the op is seeing.
     

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