[Tig] Nitmeter of choice for Lumina's ??? why 30?

Ronald Williams rwilliams
Mon Apr 17 21:12:23 BST 2006

Thanks to oktobor for supporting the TIG
  here it goes ( I don't think SMPTE will mind if I copy the text for this purpose)
5.10.1 Reference white
Using a split-field optical comparator, adjust the displayed reference white to the 
illuminant D65 and a luminance value of 120 cd/m 2 (35 fL) (see A.2). If the optical 
comparator has a variable luminance control, set the reference white on the monitor screen 
to the specified luminance value with a photometer and then adjust the comparator. 
Brightness, color temperature, and gray-scale tracking controls are interactive. Achieving 
all the correct results simultaneously requires adjustments, which reduce but do not 
completely correct the perceived error(s). The adjustment sequence must be performed 
several times, each time with smaller incremental adjustments.

That is the section in its entirety. It is also in three other documents.
Not to get anyone bent out of sorts .. as long as the interchange is working (as it has) 
its not that big of a deal.
But in HD it is a Big deal. Because the monitor currently can't do it,  the material is 
being mastered incorrectly. According to Standards

To answer the questions on this thread- not on any order.

Thanks to Bill Topazio for that section. That was added because of what was said in my 
earlier comment about Why.
The manufactures could not make all the monitors meet the numbers at the time. The 30 was 
added ,as stated in Bill response,  to be a stop gap. That is the only place it is 
mentioned. Everywhere else it is 35.
It is NOT a number unattainable as was commented. It is very easy to do now and was just 2 
years after the document went out. All except for the HD monitors.

------Maybe I am too naive to really play devil's advocate.
But it seems that the SD/HD CRT specification has never been achievable by practical 
products. Today's technology cannot get anywhere near delivery of the DCI 
specification.When does a set of technical requirements cease to be a statement of noble 
intent and when does it become a fruitless wish list?

Not too sure they are on the same page as I. All professional monitors since that time 
comply with the SMPTE Spec. Revised in 1995. As far as DI  -- you don't use a monitor to 
do DI - use a projector.

  ----Documents like the one above indicate a difference between the two white points, 
where D6500 is slightly 'greener' than 6500K (to be accurate, you can find the right x and 
y co-ordinates).  It seems that there is a lot of mix-up between the two, in textbooks and 
in broadcast monitors.  I have a
Sony broadcast monitor (1995 era) which lets you select between 6500 K and 9300 K, whereas 
newer Sony monitors will show D6500 in the menu.

Many do get the to confused! D is Daylight standard the other is lument . X .3129  Y.3290 
are the proper point for SD/HD. The 9300 is for Japan only. It is there national standard 
  --  which is about 40 minutes of one of my lectures. Because most content is coming from 
the west they now ship with 6500.

As far as the LCD instruments -- I had stated that the Spectro based units can be used if 
aligned properly--its not easy. As far as the others,  I stand by my statement that the DK 
unit is the most correct unit on the market today. We test for All manufactures and have 
documentation to support it. The Minolta unit 210 is not the best for this purpose. As a 
Minolta dealer and developer I can explain why it is used -- offline

Thanks for reading

Ron Williams

Bill Topazio wrote:
> --
> Thanks to oktobor for supporting the TIG
> --
> Perhaps part of the problem may be this slightly ambiguous statement in RP-177:
> "Some monitors, often depending on CRT type, are not
> capable of producing a linear light output level as high as
> 120 cd/m2 (35 fL). They should produce a minimum peak
> operating level of 100 cd/m2 (about 30 fL) in order to be
> considered useful in critically evaluating video signals."
>>-----Original Message-----
>>From: tig-bounces at tig.colorist.org
>>[mailto:tig-bounces at tig.colorist.org]On Behalf Of Ronald Williams
>>Ok lets try this again ... As I posted on 3/24/06 :
>>I have had similar discussions with Sony about this very topic.
>>A little background. The SMPTE spec. for Luminance on a 
>>Window pattern is 35 Ft L. Yes  it 
>>is....Why, if the spec 
>>first written in 1988, -  since 
>>revised ( for other reasons) is still 35,  are post houses 
>>using 30???
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Ronald Williams


rwilliams at landmarkcolor.com   805 480 1000  voice

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