- Written by Chris Eberle
- Published on 31 March 2014
The BenQ W7500 Projector On The Bench
The projector was installed right-side-up at an 11-foot throw distance. Test gear included an Accupel DVG-5000 Pattern Generator, i1Pro Spectrophotometer, Spectracal C-6 Colorimeter, and CalMAN 5.2 software. Measurements were taken off the screen; Carada Brilliant White, gain 1.4.
I found Cinema mode to be the best starting point for calibration so I took all measurements in that mode. Here's the grayscale tracking chart.
Like most displays, the default color temperature is too cool. The errors range from a low of 2.84 to a high of 8.24 Delta E. This is average performance.
The gain and offset controls work quite well.
This is an excellent result. All errors are now below the threshold of visibility. Values range from .30 to 2.64 Delta E. The average error is only .98.
Gamma, as you may know, refers to the rate of transition from minimum black to maximum white. Until 2011, most content was mastered using the 2.2 Power Function. Our benchmarks reflected this and the vast majority of displays are engineered to this standard. In 2011, SMPTE updated the gamma standard to ITU BT.1886. This differs from 2.2 Power Function in two major ways. First, the average value is higher at 2.4. At first glance one might think this will result in a darker overall image. However, the other difference is the lower brightness levels are actually raised above the 2.2 exponent. Check out the graph below.
At the upper end, the brightness level is almost identical but down low, BT.1886 is just a bit brighter. The end result is a little more mid-tone contrast and slightly better shadow detail with no change in the brightest parts of the image.
Even the newest displays are still engineered to the 2.2 power function so for now, we will include charts that show both standards. Unfortunately, the only way to adjust your projector's gamma to BT.1886 is with a multi-point control and that is a rare thing.
The BenQ W7500 is set by default to a gamma value of 2.4. Here is the pre-calibration trace.
You can see it rides a very straight line at the 2.4 mark. So the preset value matches the measurement pretty much exactly.
Now here's the same measurement run compared to BT.1886.
Now the tracking is not so straight. This projector is clearly engineered for a power function gamma curve rather than BT.1886.
Here's the final result using 2.2 Power Function.
With the prodigious light output available from the W7500, you can easily up the gamma to 2.4 if you want a slightly darker presentation.
The first step in achieving accurate color with the W7500 is to turn the Brilliant Color option off. It's on by default, and it doesn't have a huge impact but the results are better without it.
This is the gamut before any adjustments are made. The CIE chart on top doesn't look too bad. Red is a bit over-saturated but the other colors are pretty close. The big issue shows up on the luminance chart. All the colors are well below their brightness targets. It's time to spend some time with the CMS.
This is way better on every level. Not only are the colors' hues more in line, most of the red over-saturation has been fixed. And check out that luminance chart. It's nearly perfect. The end result is an average error of only 1.10 Delta E; completely invisible to the naked eye. This is excellent performance.
DLP projectors in this price range are not known for terrific contrast. Fortunately, help can sometimes come in the form of a dynamic iris. The W7500 has one; the feature is called Dynamic Black. Be assured, it works over the full brightness range. Because it skews gamma readings, I left the iris off during the calibration. Here are the results without the iris.
- Black Level – .0304 fL
- White Level – 18.0126 fL
- On/Off Contrast – 620.9:1
The picture looks a bit washed out at this setting. Blacks never get below a medium gray. Turning on Dynamic Black activates an excellent auto-iris. Even with the projector right behind my head I couldn't hear it working. I did see a little brightness pumping here and there but the increase in contrast is more than worth it.
- Black Level – .0095 fL
- White Level – 17.6213 fL
- On/Off Contrast – 1862.7:1
This is much better; three times better in fact. While this DLP projector won't compete with most LCD and LCoS units in overall contrast performance, this BenQ does reasonably well. And its auto-iris works better than others I've experienced.
I performed the usual battery of tests using the Spears & Munsil Blu-ray. These tests show how a display handles a variety of signal resolutions and formats. In most systems, it's better to let your player handle these chores but sometimes it's necessary to have the display deal with non-native signals like when you're using a streaming device or cable/satellite receiver.
The W7500 passes all the tests in all signal formats with the exception of 2:2 pull-down (a common failure) and mixed content vertical where it showed line twitter around the scrolling text. Two caveats should be mentioned. In order to see below black and above white information in any signal format, you must set HDMI Format to PC Signal. Auto and Video will clip all levels below 16 and above 235. Secondly, calibration settings are tied to signal format but the carry over to all resolutions. I calibrated the projector using an RGB signal. When I switched to 4:2:2 and 4:4:4 component, my settings disappeared. Fortunately, they returned when I switched back to RGB; which by the way is how to see maximum resolution performance from the W7500.
Using the Accupel, I can view special 3D patterns that make it easy to measure the amount of crosstalk between the left and right eyes. The pattern can render in red, green, blue, or gray. The viewer closes one eye and an adjustment is made until the nested squares blend together. On the W7500, it only took a few clicks to achieve this measuring a vanishingly low .08% crosstalk for both eyes and all colors. This is excellent performance. Unless the content is authored incorrectly, you won't see any crosstalk on this display.
With the high light output available, I expected decent 3D contrast and I wasn't disappointed. Using the auto iris, I measured an on/off value of 569.3 to 1. The peak white was 5.954 fL. While there's no danger of retinal damage, this is pretty bright for a $2800 projector. Go to Page 6: Conclusions