Posted on July 10, 2018 By Eric Pfoutz
BenQ TK800 4K UHD Home Theater Projector Review – Calibration Settings: Calibration Presets Notes, Best Mode Calibration, Brightest Mode Calibration & 4K Calibration
Note: The projector had over 65 Hours on the lamp before I calibrated it and took the light measurements. A brand-new bulb will most likely have slightly higher measured lumens.
The TK800 has 7 modes (Bright, Vivid TV, Cinema, Sport, Football, User 1 & User 2). I spent most of my time with Cinema, User 1 & 2. All of these modes have the same controls, what sets them apart is how these controls are preset. They all offer 3 color temperature options (Normal, Cool, Warm) 2-point grayscale adjustments, gamma presets 1.6 – 2.8 and full CMS (color management system). Note: In order to change one of the 4 color temperature presets, you must first turn off Brilliant Color. After you select you preferred color temp you can turn Brilliant Color back off if you wish.
I preformed my Best/Dark Room calibration using Cinema mode as a starting point with the lamp set to Eco. I was able to copy Cinema over to User 1 and renamed it Best/Dark. Brilliant Color is usually off by default in Cinema mode but is on in all modes including Cinema and I left it on for my calibration. Normally I would turn it off for my Best/Dark Room calibration but I came at this particular calibration knowing that lumen output needed to be at the forefront with this projector being designed/marketed as “high brightness” model. Brilliant Color increased peak white level by over 50%
Sharpness was defaulted to 10, I turned it down to 8. The TK800 lacks BenQ’s image enhancements such as Pixel Enhancer 4K, DCTI & DLTI. The white level clipped at 230 and could not be improved by lowering contrast. I did however lower it to 49 to help improve white balance calibration.
Cinema out of the box performed decently but it did show 2 – 7 DeltaE between 10 – 100 IRE. Remember we want to be below 3 and I always strive to hit 1 or less if the projector is capable. The average color temp was 7800K range, a bit cooler than our target of 6500K (D65). After calibration DeltaE ranged from 1 to 2 across the contrast range except for 100IRE hitting a DeltaE of 4. Had I lowered contrast further it would have improved 100IRE accuracy but at the loss of those precious lumens.
I usually target a 2.4 (BT.1886) gamma for my Best/Dark calibration but again with our goal of a bright image I opted for a 2.2 gamma. Now just so you understand gamma does not affect peak white output so a 2.4 would be just as bright at 100IRE, however the darker parts of the image will be a little brighter with a 2.2 so, the overall image will appear a little brighter. Post-calibration gamma averaged a little darker on the high end than I was aiming for with and average at 2.27. Peak lumen output measured just over 1000.
Measurements taken at Mid Placement with Eco Lamp.
Average Gamma Pre-Calibration: 2.31
Average Gamma Post-Calibration: 2.27 @ 1007 Lumens
White Balance calibration settings for Night mode.
Delta E is a metric for understanding how the human eye perceives color difference. The term delta comes from mathematics, meaning change in a variable or function. The suffix E references the German word Empfindung, which broadly means sensation. Simply put, look at Delta E as a measure of grayscale/color accuracy. 3 and under is considered ‘Excellent’ and imperceptible by the human eye.
For my Brightest calibration, I used Bright mode with the lamp set to Normal. Whites clipped a little sooner than Cinema mode at 228, again lowering contrast had no effect. I actually was able to increase contrast to 52 to increase peak white output and keep clipping at 228. The before calibration DeltaE was quite high with errors in the 5 to 11 range. This is mostly due to the default color temp being set to native. This gains you the most lumen output, but a very plus blue-green grayscale. So, I set the color temp to normal (just like I did with Best/Dark Room calibration). After calibration, I was able to get DeltaE down to 1-3. Brilliant Color was on by default and I left it on as it helps increase the white level output that were looking for in a brightest mode calibration.
In keeping with our goal of high lumen output and because I did my Best/Dark Room gamma at 2.2, I set my Brightest calibration gamma target to 2.00. With the default gamma set to 1.8. the TK800 measured an average gamma of 1.77. After white balance calibration that improved to 1.98. Peak white lumens measured 1933.
Measurements taken at Mid Placement with Normal Lamp.
Average Gamma Pre-Calibration: 1.77
Average Gamma Post-Calibration: 1.98 (target 2.00) @ 1933 Lumens
White Balance calibration settings for Day mode.
Lastly, I did a 4k/HDR calibration. I used User 2 mode with lamp set to Normal and renamed it 4k/HDR. I kept all of the basic picture controls at their default (50) values and lowered sharpness to 4. With the color temp defaulted to cool average white balance was quite blue clocking in with an average of 9100K. This of course sends the DeltaE off my chart which is maxed at 12. After setting it to Normal and performing a white balance calibration I was able to get it down to 6600K from 10-60IRE and in the 7300K range from 70-100IRE. DeltaE dropped to the 1-7 range. Brilliant Color was on by default and I left it om to help maximize white level output which measured 2090 post-calibration. Sharpness was defaulted to 10, turn it down to 4.
When you feed the TH800 a 4K/HDR signal it swaps out the Gamma control for HDR Brightness with values ranging from -2 to +2. HDR Brightness: -1 measured the flattest and closest to the EOTF target, however when watching various UHD Blurays at ‘0’ seemed to fair better on my screen. Although I did not spend a lot of time viewing content I did notice that performance varied a lot from scene to scene, some looked better at 0 (or even +1) and others at -1.
Note: HDR Brightness effects only the bright end of the grayscale. With other projectors it effects both the low and high end. Here it also seems to effect color saturation with it easily being over driven at +1 and skin tones seeming pale at -1 so you may need play with the color control also.
Measurements taken at Mid Placement Normal Lamp.
ETOF (gamma) Post-Calibration: HDR Brightness -1 tracked fairly flat except for the low end which was slightly brighter than the target @ 2090 Peak Lumens.
White Balance calibration settings for HDR mode.
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