AVS Special Member
Join Date: May 2008
Location: San Francisco - East Bay area
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In spite of what directions say on test/setup discs (Blu-ray or DVD), you CANNOT EVER find the right setting for Contrast using a pattern and eyes with no meter. All you can do is find the highest setting you can use that doesn't remove white levels above 235/100%. The highest setting is not the RIGHT setting. For a dark room, the RIGHT setting for 100% white is around 35 fL +/- 5 fL. You can't determine that level by eye... just not possible. All you can do is be aware of eyestrain and if you notice any eyestrain after 1-3 hours of viewing your display in a dark room, it's probably too bright and you should reduce the Contrast setting until you get to a point where there's no eyestrain. It takes a good long while to detect eyestrain though... it's not something you can estimate in 5 seconds, though if you are squinting at a bright screen, chances are the screen is much too bright.
A common scenario is for the Contrast control to have settings from 0-100. The default might be 100 and you might have 60 fL or more (for an LCD TV) when the Contrast control is set that high...some TVs may even produce 150 fL when the Backlight control is turned up all the way. Plasma TVs rarely will get brighter than 60 fL which is still double the luminance you want in a dark room.
So you display a Contrast pattern and you learn that at a setting of 85, you can see all the white steps from 220-253, but if you go higher, you start losing steps at the high end of the range. That's not a seriously bad problem, few, if any people will be able to detect whether white steps stop at 235 or whether they remain visible all the way to 254. But if you can see steps about 235, you may as well setup so they are visible. But if you had a meter, you might find that the 85 setting for Contrast produces 52 fL which is still too bright. Your meter (if you had one) might tell you that a setting of 65 produces 35 fL for 100% white in a dark room which is about where you want to be. So even though the Contrast test pattern told you 85 is the highest setting you can use without losing steps above 235, that doesn't mean 85 is the right setting. This is a hypothetical example, not based on any particular TV.
Some TVs never lose steps about 235 no matter how high you set Contrast. With those TVs, eyestrain is your only reference for finding the best setting if you do not have a meter.
And there are some TVs that ALWAYS clip steps above 235 no matter what Contrast setting you use, so once again, eyestrain is all you have to use to find the right setting if you don't have a meter.
"Movies is magic..." Van Dyke Parks
THX Certified Professional Video Calibration
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Widescreen Review -- Home Theater & Sound