AVS Forum Special Member
Join Date: May 2008
Location: San Francisco - East Bay area
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"should get" and "do get" are not equal in this case.
However, even with panel displays jacking-up brightness for 3D modes, 100% white measurements through activated 3D glasses are still a fraction of what you read without the glasses even when Contrast and/or Backlight settings are much higher than the settings used to achieve 30-35 fL for 100% white in 2D mode. If you do NOT make the display brighter for 3D mode, the dark end of the luminance range can get so dim it's essentially too dark to see any detail.
BTW, the current SMPTE spec for cinema screen brightness is 16 fL +/- 4 fL for 2D.
When I measure 3D home theater projectors I typically measure 2 - 4.5 fL in 3D mode and there's never any trouble getting any of them to 16 fL with the 1.0 gain Stewart StudioTek 100 screen that I use. But achieving 2-4.5 fL requires more light from the projector... simply putting the projector into 3D mode, activating the 3D glasses and doing measurements produces measurements considerably lower than the 2-4.5 fL I end up getting and I have to say... 4.5 fL is MUCH more impressive than 2 fL when viewing 3D content at home. To get more light, all the usual suspect can or are called into play... if there are multiple auto iris modes, using a mode that does not close the iris much helps. If the projector has a fixed iris, opening it either all the way or partially is required. Contrast may be set higher also. And finally, if low lamp mode is used (which is often the case with my 72" wide 1.0 gain screen (viewed from 7.3 feet or 2.9m), the projector may be switched to high lamp mode for 3D.
What's most surprising about 3D, perhaps, is that 4.5 fL for 3D doesn't seem particularly dark when you are used to 16 fL for 2D. Presumably when both eyes see light constantly (even though 1 eye is seeing nothing half the time) our eye-brain system must somehow compensate for the low MEASURED amount of light. On the other hand, the projectors I've used that can't produce more than 2 fL (same 1.0 gain, fairly small screen compared to some) do seem fairly dim and unsatisfying.
"Movies is magic..." Van Dyke Parks
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