Posted on December 20, 2017 By Ron Jones
Optoma UHZ65 4K Laser Projector Review – Performance: Image Brightness, User Picture Mode Color Performance, HDR Picture Mode Color Performance, Black Level/Contrast, Noise Level
1/1/2018 Update – Some corrections and additions were made to the following performance information.
The Out-of-the-Box (uncalibrated) image brightness, in Lumens, is listed in the table above for each standard picture mode. The above measurements were made with the projector’s zoom lens at it mid point. Using maximum zoom increased the projector’s brightness by 10.9% and using minimum zoom decreased the brightness by approx. 16.9%. Thus when operated in “Bright” picture mode and at maximum zoom the UHZ65’s light output slightly exceeds Optoma’s spec. for 3000 lumens.
In terms of brightness uniformity the UHZ-65 didn’t perform as well as some competing projectors. I measured a 42% drop in brightness in going from the enter of the projected image to the dimmest corner (top-left in this case).
NOTE: See the post-calibration brightness results below for “User” and “HDR” picture modes.
I calibrated the User picture mode for use with regular HD (or UHD) video with standard dynamic range (SDR). This is video using standard Rec. 709 color gamut.
The post-calibration brightness measured 1133 lumens, which was about 500 lumens less than the User mode brightness with the factory default settings (as listed in the table above). In both cases this was with the projector’s laser light source set to operate at full brightness when displaying a reference 100% white test image. The calibrated User mode color temperature was 6564K (average) and varied between 6459K and 6729K over the range grey scale range of 10% to 100%.
The two figures below show the color balance/grey scale tracking first with the factory default settings for the User picture mode then after calibration. The mean Delta E (i.e., error) for color balance across the grey scale measured 1.4 while a much worse 18.4 before calibration.
The two figures below show the measured color gamut first before calibration then after calibration. The results for saturation levels of 25%, 50%, 75% and 100% are shown for each of the 6 primary and secondary colors. Using the projector’s Color Management System set of adjustments, I was not able to fully correct for some of the color points nor obtain ideal tracking across the saturation levels for certain colors (e.g., blue). This result in some color inaccuracies under certain conditions. Even so, the mean Delta E (i.e., error) measured 2.3 after calibration as compared to 4.7 before calibration.
I calibrated the HDR picture mode for use with UHD video with high dynamic range (HDR). While such UHD/HDR video is usually also using a wide color gamut (WCG) the UHZ65 is limited to a color gamut this is very close to Rec. 709, so that’s what the calibration is based on. I set up the projector using the HDR picture mode with Brilliant Color set to 8 and Dynamic Black set to 2.
The post-calibration brightness measured 1558 lumens, which was similar to the HDR mode brightness with the factory default settings (as listed in the table above). The average color temperature after calibration was 6580K (down from 8932K before calibration) and varied over the range of 6402K to 6847K over the grey scale range from 10% to 100%.
The use of the Brilliant Color and Dynamic Black functions make certain of the standard calibration results invalid, but the color balance and color gamut results presented below were the basis for this calibration.
The two figures below show the color balance/grey scale tracking first with the factory default settings for the HDR picture mode then after calibration.
The two figures below show the measured color gamut first before calibration then after calibration. The results for saturation levels of 25%, 50%, 75% and 100% are shown for each of the 6 primary and secondary colors. Using the projector’s Color Management System set of adjustments, I was not able to fully correct for some of the color points nor obtain ideal tracking across the saturation levels for certain colors.
As mentioned earlier in this review, the UHZ65 has only modest native on/off contrast and a relatively high black level when it has been calibration for correct reference black level. I found the factory default setting for the brightness control was too low and as a result the dark grey levels on the grey scale were being clipped (not displayed). Adjusting the brightness control to correctly display the dark greys did raise the black level and lower the contrast ratio of this projector, as compared to the factory default settings. Also the projector’s contrast control was set too high resulting in clipped brighter near whites on the grey scale and this was also corrected for the calibration, at least for the non-HDR white levels.
The following contrast ratio (CR) measurements were made using the calibrated User picture mode. The first measurement was for the native on/off CR of the projector, while the next three were for when the Dynamic Black feature was active at each of the 3 available settings. The Dynamic Black feature dims the projector’s laser light source the most for when picture is fully black, but less dimming when there is actual content in the image. Remember however, dynamic black not only lowers the black level, but also the lowers of the brightness of the brightest whites by an equal amount. I found that use of the Dynamic Black feature at a setting of 1 or 2 can make for a more dynamic looking picture when viewing a movie, but with a few visible cases of black level “pumping”, especially with the Dynamic Black set to level 2 (or even worse at a setting of 3). Remember the measured values below are for on/off Contrast Ratio (CR) when the brightness is measured with a maximum full white test image then with a full black test image (that’s where the Dynamic Black feature will dim the laser to make for a darker black).
Note the Dynamic Black 3 mode’s actual on/off CR is probably higher as the above value may be limited by the measurement environment.
So Dynamic Black appears to be a viable alternative to having a dynamic iris, as found on most of the better home theater lamp-based projectors. However, you can get too much of a good thing and the result will be black level pumping which can be distracting to the viewer.
The UHZ65 is spec’ed at producing a 33 dB noise level at full power. However, I found this projector’s noise level to be lower than most projectors that carry a 30+ dB rating. It should be quiet enough for most home theater environments, even when operated at full power.
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