Por eso mismo sólo hay que ver estas mediciones de negro en un HW50 con
iris fijado calibardo a poco más de 17 ft-L dando valor de negro de 0.0065ft-L y cómo éste negro se hace muchísimo más profundo cuando aplicas el iris dinámico y éste se cierra pasando a valor de 0.0008 ft-L:
Full-On/Full-Off Contrast Ratio: 20,894:1
Except as noted, all of the measurements (and charts) here are for 2D operation and were taken on a 96-inch-wide Stewart Filmscreen StudioTek 130 screen (gain 1.3). The projector was in the low lamp mode, the Advanced Iris was on Auto Full, the Contrast Control was on 70, and there were approximately 160 hours on the lamp.
The above contrast ratio was taken with the projector positioned at approximately 14 feet from the screen using a Minolta T-10 light meter to measure directly off the lens. The peak-white level on the screen was 17.58 foot-lamberts measured with a Minolta LS-100 light meter. From these two measurements, we calculate that the black level on screen was 0.0008 ft-L. (The LS-100 will not measure below 0.001 ft-L, thus the reason for the two-meter interpolation.)
Using the same technique, with the Advanced Iris turned off and the manual iris set for an onscreen brightness of 17.55 ft-L, the black level increased to 0.0065 ft-L, and the full-on/full-off contrast ratio dropped to 2,710:1.