Optoma GT720 Projector Calibration and Settings

Posted on July 8, 2011 by Art Feierman

We calibrate every home theater that we review. The Optoma GT720 received the usual treatment. I "played" with the GT720 for a couple of days, passed it off to Mike for calibration and measurements. 24 hours later, I'm back to watching it. Ours is a pretty standard calibration, there's always more done by some of the "hi-end" calibrators. Our calibrations, including the Optoma GT720, are normally limited to a grayscale calibration, along with brightness, contrast, color saturation, etc. Only in very special circumstances will we calibrate the individual colors, in which case we discuss why.

Optoma GT720 Color Temperature

Before we provide our settings, lets see what we started out with: Pre calibration, these are the color temperatures over the grayscale range:

Color Temp over IRE Range (Best Mode, Pre calibration):
Standard
30 IRE	8172
50 IRE	8142
80 IRE	7685
100 IRE	7718

Standard offered the best looking color, but produced a very cool (bluish) image.

Lumen Output and Color Temp at 100 IRE (mid zoom):
Brightest	1653 @ 7232
Standard	1529 @ 7718
Theater	1296 @ 7891
Dark Room	839 @ 7993 (By default, Dark Room is on Eco lamp. With Eco off, Dark Room has same lumens as Standard)
User 1	1108 @ 10280
User 2	1108 @ 10277

NOTE: There are three other color temps in addition to Mid, but Mid gives the highest lumen output.


GT720 Brightness (Eco Lamp On, Brightest mode)	1306 lumens

That represents a drop from 1653 lumens at full lamp power. The math says that's a drop of an almost perfect 21%. Most projectors drop 20 to 25% when going to their eco - low lamp, power mode.

Optoma GT720 Basic Settings

Settings for measurements (default values are in parenthesis):
	Cinema	Bright	Presentation	Classroom	Blackboard	Game
Contrast	-46	-46	-47	-46	-44	-47
Brightness	-50	-50	-49	-50	-50	-50
Color Temp	(Warm)	(Warm)	(Medium)	(Warm)	(Warm)	(N/A)
Degamma	(Film)	(Video)	(Graphics)	(Film)	(Film)	(Std.)
Brilliant Color	-6	-10	-10	-8	-10	-10

In addition to calibrating Red Green and Blue for a correct grayscale balance (6500K), there are a number of other settings that come into play. Typically Contrast and Brightness (white balance and black balance), need to be done first. Color saturation and gamma also need adjustment.