Dallas Sight and Sound's analyzer miscalibrated

Discussion in 'Archived Threads 2001-2004' started by Robert P. Jones, Jul 7, 2001.

  1. Robert P. Jones

    Robert P. Jones Second Unit

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    Anyone who has had their set calibrated by Dallas Sight and Sound should check back with them. On my second trip back to Texas, I did a cal on Dave Willingham's Mit 73907, whose TV had been ISF cal'd by DS&S, and it was HORRENDOUSLY off in its color scheme. This was apparent by eye to me immediately, even tho the readings on the ISF sheet they'd left him all hovered around D6500K, just like they should.
    After Dave had a chance to see my ISF optical comparator in action, he saw it too.
    After talking with Dee at DS&S, the color analyzer they used was examined and found to be OFF - miscalibrated - by 3,000 degrees Kelvin!
    Last I heard from Dave, DS&S was contacting all the customers they could find, to realign their messed up ISF calibrations for the past who knows how long.
    Mr Bob
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    Robert P. Jones
    Image Perfection
    San Francisco Bay Area, USA
    [email protected]
    510-278-4247
    www.imageperfection.com
     
  2. Tom-Scott Gordon

    Tom-Scott Gordon Auditioning

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    Bob, I tested mine thoroughly tonight against a Mac monitor with an eps file. By my eye, I'm still limited to using a (45.cc -wratten) offset and a custom setting. This Sencore business is maddening.
    I don't need either a comparator, or a $@%meter to see how Bloody Red my 'calibrated' grey patch looks at the normal setting.
    I read that cheap ballasts emit 180% THD, if you always use a comparator, look for a GE low-emmisions balast with noise @ 40%THD!
     
  3. Robert P. Jones

    Robert P. Jones Second Unit

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    Using a good, well set up computer monitor that you can totally trust is just as good as using the ISF Optical Comparator. Comparing is the issue, and correct is correct.
    Mine was doublechecked by Joel Silver hisseff via his $7K Minolta point and shoot instrument, and found to be dead on at the proper coordinates. His instrument doesn't read out in degrees Kelvin, but in the coordinates on the 1931 Minolta Chromaticity Chart. He knows his instrument so well he has no need of the assistance of the built-in reference indicators of a color analyzer; neither do I.
    But unlike myself - I am adept enough to do most greyscales strictly by eye - he is so adept that not only can he do that also, but he can know, just by the coordinates read by his Minolta unit, that my 8 year old optical comparator had actually drifted off in the direction of the green; showed more green than could be classified as dead on, like the fresh one I was buying there at the ISF training. It could still be used, just was not dead on anymore.
    And he saw this just from looking at the coordinates read out by his instrument.
    We put the old and the new comparators side by side, and bingo - old one was slightly greener than the new one.
    What kind of TV do you have? From your description, I'd wager it's a Mit. Nearly all their greyscales these days are arriving at the customer's home very pink, both in High and Low color warmth settings, and they of course stay that way. Never mind their always intrusive red push...
    In all fairness, tho, I just in the last few days did a cal on a new 46807, and there was no red push! I was amazed -
    BTW, if doing greyscales by eye, it is best not to use strictly the grey patches of different light levels. That's fine for instruments, but the human eye needs comparisons to get it right. The 4 VE blocks on the right hand side in their pluge pattern, plus using the right hand stripe on the left for darkness doublecheck, is the best pattern I know of for greyscales done by eye. Analyzers don't pick up anything below 20 IRE, so the dark areas have to be done by eye anyway. And the vertical stripe needs to be as close to grey as you can make it. If the absolute black is greenish, only so much of that can be allowed, but you sometimes can't get rid of all of it, because then you have too much magenta/purple/redblue in your darker greys of the block pattern, 2 lowest blocks.
    Mr Bob
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    Robert P. Jones
    Image Perfection
    San Francisco Bay Area, USA
    [email protected]
    510-278-4247
    www.imageperfection.com
     
  4. Robert P. Jones

    Robert P. Jones Second Unit

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    PS -
    The topmost block of the 4 blocks in the VE pluge pattern is not the best one to use for white balance during your greyscale op, BTW. It usually looks yellowish to me, and it's easy to get too much blue in there to compensate, which looks OK on the pluge pattern, but not OK on actual video material.
    Its best use is during the precision blue defocussing op, if you're doing it, where the quick comparison of with and without the defocussing shows up instantly in that topmost of the 4 blocks, as long as the Contrast is not below 50%, and preferably at 80-100%, just for that op, then turned back down to 50% or so, or whatever you run it at.
    Best way to do white balance by eye is to use regular video material, paying special attention to whites. B/W material is also good for this, also paying special attention to the whites. Getting block 3 of the VE pluge pattern to accurate grey, preferably using the optical comparator as doublecheck, can help.
    The whites should appear as nice and creamy, rather than strongly blue-white.
    Mr Bob
    ------------------
    Robert P. Jones
    Image Perfection
    San Francisco Bay Area, USA
    [email protected]
    510-278-4247
    www.imageperfection.com
     

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