Originally Posted by darshan_4
hey guys i just recently bought tc-p50V10 tv...
Editors' note, March 3, 2010: Testing conducted on 2009 Panasonic plasma TVs, similar to this one, has revealed that black-level performance has become noticeably less impressive within what is typically the first year of ownership. As a result, we don't feel confident that the initial picture quality of this TV, as described in the review below, can be maintained over the course of its lifetime, and therefore find it difficult to recommend. Its Performance score has been accordingly reduced by one point to better indicate comparative picture quality after 1,500 hours of use.
Update April 2, 2010: Long-term testing shows similar loss of black level performance in two other Panasonic plasmas tested by CNET. Click here for details.
Panasonic has confirmed that its plasma TVs reproduce brighter black levels by design as they age, but will not divulge exactly how much brighter after how long. New testing conducted by CNET provides some hints.
Results from two aged Panasonic plasma TVs purchased in 2009 indeed show brighter blacks, and correspondingly reduced picture quality, compared with similar 2009 models with fewer hours.
The two aged TVs were a TC-P50G10 owned by CNET Senior Editor John Falcone and a TC-P42G10 loaned to us by CNET reader Efrain Perez. Both had approximately 1,500 hours of use, which at the average rate of 5.2 hours per day works out to about 9.6 months of age, at the time testing was conducted. We also measured another 50-inch TC-P50G10 and a 50-inch TC-P50V10, each with about 500 hours.
According to our measurements, the models with 1,500 hours both reproduced black at 0.023 footlamberts; the 500-hour models measured 0.008.
In an attempt to corroborate the measurements with real-world material, we conducted a side-by-side viewing session, attended by CNET staff and otherwise modeled after our standard TV test procedure, that pitted Efrain's TV against the 50-inch V10. When we originally compared a G10 with the V10 in 2009, using new review samples, we called their black level performance "basically the same."
That wasn't the case this time around. In dark scenes from "The Dark Knight" on Blu-ray, the 500-hour V10 clearly displayed a darker shade of black than the 1,500-hour G10, leading to more-realistic reproduction of nighttime city-scapes in Chapters 2 and 8, for example, the rooftop parlay in Chapter 8, and the silhouette of Bruce Wayne as he enters the room in Chapter 18. The difference was also visible in letterbox bars, albeit less so, in numerous brighter scenes. This viewing session was conducted with each TV set to the default THX picture mode, with no adjustments made to any picture settings.
The differences we observed and measured could be the result of what the company calls the normal aging process. According to Panasonic's statement, made after we first reported user complaints about this issue: "...Panasonic Viera plasma HDTVs incorporate an automatic control, which adjusts an internal driving voltage at predetermined intervals of operational hours. As a result of this automatic voltage adjustment, background brightness will increase from its initial value."
For what it's worth, however, these increases in black level performance over time don't seem normal in our experience. I haven't noticed any sudden change in black level on my 2005 Panasonic at home, for example, and a Pioneer Kuro we've used as a reference since September 2008 shows no increase.
We contacted Panasonic with these test results but the company declined to comment because of pending litigation related to the issue.
Whether the increase is noticed by everyone or even a majority of viewers, the results we measured on two different models, and saw in our side-by-side comparison, are enough to make us modify our reviews of all 2009 Panasonic plasma TVs accordingly (yet again). Their Performance scores will be reduced across the board by one point, bringing them more into line with the competition in light of their increased black levels.
It doesn't bode well for Panasonic.