Projection Screen Reviews

Except as noted, measurements were made in a darkened room, using CalMAN measurement software from SpectraCal, together with Photo Research PR-650 and Klein K-10A color meters, a Minolta LS-100 light meter, and the VideoForge pattern generator from AVFoundry. The video projector was a JVC DLA-X55. While the general conclusions should hold with other projectors, the actual numbers shown here apply directly to that projector and lamp only.

Different screens will usually demand different color calibration settings on the same projector, and the Slate was no exception. The JVC projector used in the testing required gray-scale recalibration, but following that exercise, there was little to complain about in the Slate’s color performance. Post-calibration, its gray-scale Delta E did increase to 5.37 at 100% brightness, but it never exceeded 1.18 (90%) at any other point and averaged 1.06. (Delta E is a figure of merit indicating how close the result comes to the D65 color standard, with values under 3 to 4 generally considered optimum.)

With respect to on- and off-center uniformity and the effect of ambient light, the Slate’s measurements were compared with those made on a small sample of the Stewart Filmscreen StudioTek 130. (A full StudioTek 130 was available to us, but using it would have meant moving either the screen or the projector, thus introducing additional variables.)

Measured from a center position directly behind the projector, the Slate was nearly as bright as the StudioTek, roughly confirming SI’s gain specification of 1.2. However, when the measurement was taken from a seating position approximately 30° to the side, at about the same distance (roughly equivalent to the outside seat on a very wide sofa positioned 11 to 12 feet from the screen), the center-screen brightness of the Slate dropped by 41%, while the brightness from the StudioTek sample dropped by only 18.4%. This was likely no accident, as it is this characteristic that makes the screen less sensitive to ambient light. And as noted in the review, this dropoff was generally not obvious on normal program material. You can see it if you look for it, but mostly on large swaths of white or pure color, such as a bright blue sky.

With all room lighting turned off, and with a center-screen peak-brightness level of just over 16 foot-lamberts, the black level from the JVC projector measured 0.0015 ft-L on the Slate—a typical reading from a home projector with state-of-the-art blacks. But with two lamps with their 50- and 60-watt bulbs turned on and positioned as noted in the review (about 3 feet beyond the two sides of the screen and about halfway between the screen and the projector), the black level measured 0.04 ft-L. In other words, the full-on/full-off contrast ratio dropped from 10,800:1 with the lights off to 405:1 with the lights on. The latter, of course, will vary widely depending on where the lights are located, but it’s unlikely to ever approach the lights-off value. As a comparison, with the StudioTek 130, the lights-on, full-on/full-off contrast ratio dropped to 265:1—definitely worse than on the Slate.—TJN