HP z27x Review
by Chris Heinonen on December 2, 2014 4:00 PM ESTSurprisingly the HP z27x does not fare well on our uniformity testing. With most professional displays, having good uniformity is important because of their target market. This makes the performance that we see from the HP z27x all the stranger.
White Uniformity sees a lot of light drop-off at the edges of the screen. A very good display will only drop down 10% to 180 cd/m2 or so but the HP falls all the way to 153 cd/m2 in one zone. This fall-off of almost 25% is much higher than would be expected, and is something you can see when you have a uniform field up on the screen.
Black Uniformity is similar, with those same zones on the display having a lot of light fall-off leading to darker blacks. Having darker blacks is always good, but these are dark because of uneven backlighting which is not something we want to see of course.
The contrast uniformity shows that these backlighting issues are pretty consistent. There is some variation in the contrast ratio, but the minimum level is 900:1 and it goes up to 1,047:1 in one zone. This is better than we measured with the APL patterns (uniformity uses full-field) and everywhere on the display has a good contrast ratio. The contrast uniformity measures very well on the HP z27x.
The biggest issue is the color uniformity. This is probably tied back into the white uniformity, as the luminance level being incorrect will cause the colors to be incorrect. One zone, the very dim one, has an average dE2000 of almost 6.0 compared to the center. This poor backlighting causes the colors to all appear off compared to what is in the center. The panel itself might be uniform but if the backlight is not, what you see on the screen will not match up.
Overall the uniformity measurements of the HP z27x surprise me. I expected much better results from the monitor because of its target market. The panel might calibrate to be very accurate, but what you see in the center of the screen is not going to match up to what you see on the edges of it.
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ant6n - Wednesday, December 3, 2014 - link
@Chris: when seeing this article in rss, it's not clear that this is a monitor review (the word 'display' comes up nearly last).chowyuncat - Wednesday, December 3, 2014 - link
Could you put Apple's 27" Cinema or Thunderbolt display's input lag in your monitor reviews?cheinonen - Sunday, December 7, 2014 - link
I don't have one so I can't do that, and they don't have HDMI ports so I can't measure it the same way either.marsupilami - Friday, December 5, 2014 - link
Am I the only one who thinks this article lacks an introduction?Good review otherwise although I agree with kyuu regarding the uniformity issue, unless the monitor was purchased by AT I don't see how requesting another sample would've made a difference. And even then you can publish both sets of numbers and let the readers draw their own conclusions. As it is we have no clue whether the results are due to a damaged sample or simply poor performance.
SanX - Sunday, December 7, 2014 - link
Who needs QHD? Who needs 27"? Are gamut pros happy that they dont have yet 4K minimum 30"- 40" monitors?mtbakerstu - Saturday, May 9, 2015 - link
Chris, thank you for what I thought was a very good review. My question is not just to you, but to the community that has participated in this forum as well. Is there any new consensus on the uniformity issue that Chris raised? It does seem an achilles heel, if the issue is not specific to the z27x unit that Chris evaluated. Since last comments posted, has anyone purchased (or know anyone that has purchased) a z27x to confirm or disclaim what Chris communicated as a serious issue for the model? There aren't many options that cover the full range of color gamma options at this price point, so I am inclined to buy one, but felt I should first check into the community. As an alternative, I am considering the z24x, but perhaps uniformity is an issue with this model as well. Thanks in advance for the any additional feedback from the community here.kflorian - Sunday, July 12, 2015 - link
Anybody have an accurate weight for this WITHOUT the base?