CRT Calibration Black Point/Black Level

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  • #31382

    Paul85
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    Hi. I’m in the process of calibrating my CRT monitor, the measurement part prior to calibration, and would appreciate some feedback on the results I’m getting .

    I’ve attached some pics showing measurement results along with my DisplayCal settings, a report on my un-calibrated monitor, and the brightness and contrast settings I’m using in my OSD.

    With some minor tweaks to red & blue (there’s no green control) in my monitors OSD, I’ve got the RGB levels centered on the ‘White Point/White Level’ section, but I’m wondering why the RGB levels are off on the ‘Black Point/Black Level’ section? Especially the green being so low.

    Regarding the help text on DisplayCal about adjusting ‘RGB offset controls’ to correct this, would those controls generally be available on a monitors OSD? Because I can’t find any offset controls on mine. Do they perhaps appear as potentiometers inside the case for a CRT monitor?

    Also I guess the brightness is low at 60 cd/m2?.. But yesterday I was able to locate and adjust the monitors focus potentiometers, along with a screen potentiometer that effects brightness, and I was able to lift the brightness up quite a bit before returning it to the level it is at now, as reported on the attached picture, so there is scope for me to increase brightness. What would be a good target to aim for on a CRT monitor? I read a post where someone recommended around 80-95 cd/m2, does that sound about right?

    • This topic was modified 3 weeks ago by Paul85.
    • This topic was modified 3 weeks ago by Paul85.
    • This topic was modified 3 weeks ago by Paul85.
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    #31445

    Paul85
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    Since my monitor OSD menu doesn’t have RGB offset controls, is it ok for me to continue with the calibration even though these black point results are off?

    • This reply was modified 2 weeks, 2 days ago by Paul85.
    • This reply was modified 2 weeks, 2 days ago by Paul85.
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    #31450

    Алексей Коробов
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    You have 100:1 contrast ratio, but black point should be significantly raised in green, so contrast will become worse. Probably, potentiometers tunning allow to get some better value, but all this work is not more than a game. This display is not acceptable for any real work, except of “textual and signal” operator panel. You need more than 700:1 (850:1 is reasonable value) for photo editing and much more for video editing. Paper emulation allows low contrast sometimes (black paint on matt uncoated paper is actually grey), but this level should be 300:1 at least and you need good transition of dark tints. Gloss paper holds high enough contrast. Brightness level around 80-100cdm is really good for prepress tasks and is usefuls for all-day office work with almost white screen. I calibrate my display for 85-90cdm, but I recommend 140cdm for photo editing on small displays, most useful brightness level I meet is 135-190cdm. Large panels should be darker to prevent eyes fatigue.

    #31452

    Алексей Коробов
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    P.S. Try to start the same process at night time with no lighting (really dark room). As I remember, CRT screen disperses a lot of falling light. Its thick glass also helps side light to go into colorimeter lens.

    #31455

    Paul85
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    Thanks, but I’m confused when you say my constrast ratio is 100:1, becasue the “report on un-calibrated monitor” picture I attached shows the contrast ratio as 1863:1? I’ve never seen the ratio anywhere close to 100:1 on the “report on un-calibrated monitor”, the last tweaks I made reported it being around 2400:1.

    I’m just using this monitor for gaming btw, thought it would still be worth calibrating though.

    I haven’t properly explored inside the CRT case yet, but so far I’ve only come across potentiometers for focus and screen/g2 voltage. I’ve tried lifting the screen/g2 voltage pot whilst the colourimeter is on the screen and it does raise the green, and I can get the RGB meters balanced at centre, but then the display becomes much to bright and washed out (around 110cdm), so raising the green/correcting the RGB black point by using that particular pot doesn’t seem like a viable option. Do CRT’s have RGB offset pots?

    Oh yeah, that’s the way I’ve been doing my measurements, at night with my light off.

    • This reply was modified 2 weeks, 1 day ago by Paul85.
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