RPTV Calibration Questions

Discussion in 'Displays' started by Vader, Mar 7, 2006.

  1. Vader

    Vader Supporting Actor

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    Derek
    After reading several posts concerning RPTV calibration, I have a couple of questions for the experts here. I have always tried to be extremely careful where my RPTV is concerned (a Mitsu WS65511), especially where the possibility of burn-in is concerned. So much so that the first thing that I did when I got the set was to turn the contrast and brightness waaayyyyy down. After subsequent calibration with DVE:

    1)The brightness was easy; it is currently set at approx 55%
    2)As for contrast, I could not see the “Blume” that DVE refers to, so I used the color bars and set it just above the point where true white becomes off-white. The final setting is about 27%.
    3)The sharpness control never seemed to make any difference, whether at 0% or 100%, so I turned it completely down.
    4)Colors I got as close as I could given the Mitsu’s red push.

    I never considered VSM until reading a few posts recently, so I checked… sure enough, it was on. One thread mentioned the possibility that VSM could contribute to tube wear, so I immediately turned it off. The picture became extremely soft and indistinct (the sharpness is completely off), but I have gotten used to the fake detail added by VSM over the last few years. I am thinking this is why the sharpness never had any effect: VSM. Last night, I tried setting the sharpness using the DVE test patterns. I focused on a fine detail pattern, and increased the sharpness until the blurriness was minimized (to my eyes), and I never noticed any of the artifacts VSM had produced (I was switching back and forth). To my surprise, the best picture was obtained with sharpness set full-up?!? I know from reading here that excessive sharpness = bad… So, long story short (too late?), here are my questions:

    1) I have ingrained in my brain cell that torch mode = running brightness and contrast full-on. As a result, the idea that full-on anything is potentially bad follows. I don’t know how sharpness works (or VSM, for that matter… what’s the difference?), but could running it high damage the tube?

    2) Since I have been so used to the fake detail afforded by VSM, what can I look for in the test patterns to know I’ve got it “right”, without going too high (even at full-on, I still do not see any of the VSM edge-enhancement artifacts)?

    3) I know that it is best to wait until the set warms up (about 30 min) before adjusting the convergence. Is this also true where sharpness is concerned?
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    As mentioned in the other thread, I would not be concerned about VSM and tube wear. But turn VSM off for image quality reasons.

    Sharpness control is usually a frequency peaking function to boost the HF portions of the video signal that tend to suffer the most signal loss over distances and cause picture softness. Boosting this too far over-enhanced high frequency transients and over-emphasis HF material which leads to unpleasant ringing artifacts.

    If you use a frequency sweep pattern, ramp sharpness up and down and you may see the high-frequency portions of the sweep become blurry at one extreme then become over-emphasized and brighter at the over-sharpened extreme. It's been a long time since I've looked at frequency and sharpness patterns on DVE, but I find the Avia pattern extremely useful for this. Sharpness shouldn't have any effect on tube wear, similar to VSM.
     
  3. Vader

    Vader Supporting Actor

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    Thanx, Chris!

    What about the warmup time for the TV? Do I need to let the set warm up before setting the sharpness (similar to convergence)?
     
  4. Phil Iturralde

    Phil Iturralde Screenwriter

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    Yes, ... all the optic's are related and you want everything to be in operating temp. and stable before adjusting & calibrating the Video.

    45 mins. is the usual warm-up time to stabilize the video display device.

    Phil
     
  5. ChrisWiggles

    ChrisWiggles Producer

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    It's always good to warm up a display before adjusting things.
     

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