Re: Mitsubishi Profiling Woes
Re: Mitsubishi Profiling Woes
- Subject: Re: Mitsubishi Profiling Woes
- From: William Hollingworth <email@hidden>
- Date: Fri, 23 Mar 2001 15:10:30 -0600
At 12:33 PM 3/23/2001 -0800, Doug Brightwell wrote:
William...
Thanks for your note. Just to clarify...
> You stated that the 2040 looked to have less contrast (indicating a higher
> black level, and/or a lower gamma set in the LUTs), but yet in Optical you
> can't match the luminance. I think this is where the problem lies. Do NOT
> use the brightness control to try and match the "luminance" levels of
> white. Use the brightness control only to match the black level. Once that
> is set, DO NOT adjust brightness again. If the luminance level of white is
> still not high enough, then use the Contrast control, or failing that,
> increase the RGB gains slightly (at the same time try to maintain the
> correct white point - use the Optical Colorimeter tool if necessary).
>
> You also stated that your target luminance is around 112. If you are using
> a white point of D50 or D65, then you can't achieve this kind of level for
> very long. It is way way too high, especially for a 22" monitor. Typically
> you should use a luminance level of around 80-85 cd/m^2.
I normally run the luminance level around the level you recommended. I only
cranked it up this time in order to try to match the black (not white) level
in Optical. Even with them cranked up, and with brightness at 100%, I still
couldn't match the black level. I didn't try to match the white level since
both contrast and brightness were already at 100%.
What black level are you trying to match? The 2040 is set to achieve about
1-3 cd/m^2 black luminance with brightness and contrast set to maximum. Any
more than this and the image would look totally washed out.
Also, I don't use the Optical startup app. I disabled it a long time ago at
someone's recommendation. So the monitors are set based upon what I set them
to in the monitors control panel. (Someone else on the list had commented
about that.)
Again, be sure that there isn't anything setting the LUTs in your video
cards. You may want to try swapping the two monitors onto the opposite
video cards and see if there is any difference.
Is there anything I could have set incorrectly in the OSD that could be
causing this, other than the RGB levels in Pre-Cal?
Also check the "Clamp Pulse Position" on the OSD. This should normally be
set to "back".
After seeing a posting from Paul Guba at email@hidden, I thought I
should mention some other weird phenomena that might be relevant. Paul
wrote:
> sort of misaligned image very noticable around text. I too thought it
> may have been a cable problem but it proved not to be. Once I spoke
> with someone at Mitsubishi they sent me a replacement with no questions
> asked.
This sounds like it could either be mis-convergence (Red, Green and Blue
misalignment that is correctable using the convergence controls on the
OSD), or video ringing (electrical echoes along the video cable) that shows
up as faint lines to the right of high contrast transitions (like text). Be
sure to have the video cable tightly screwed in. Also some video cards have
much worse ringing than others. Never use low quality video cables or
extension cables. A good BNC video cable will cost about $45.
In my case:
- I occasionally, I see thin vertical black lines on the screen about the
same width as the two horizontal stabilizing wires. They come and go, and
seem to depend on the angle that the monitor is tilted.
This is probably grille entanglement when two of the vertical aperture
grille wires stick together. You can normally get this to fix itself by
displaying a white window over the area which causes localized heating of
the grille and the wires will unstick themselves. Another method is to tap
the monitor on the side to jolt the wires.
- the image wiggled very slightly, more so with the BNC input but also with
the multi-pin input. I turned adjacent electronic devices on and off, trying
to see if there was some king of elecromagnetic interference. Nothing made
any difference. I finally banged the side of the cabinet and the wiggling
stopped.
I'm not going to recommend anyone bang a monitor :-) However you were right
to suspect electromagnetic interference. Even air-conditioners 30 feet away
can cause shimmering effects on large CRT monitors. Other suggestions are:
1. Try adjusting the corner purity controls to see if you can reduce any
shimmering in the corners of the screen.
2. Try adjusting the video refresh rate in the monitor control panel.
3. Try reorienting the monitor if at all possible.
Regards
William Hollingworth
Senior Product Development Engineer
NEC-Mitsubishi Electronics Display of America, Inc.
http://www.necmitsubishi.com