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Discussion Starter · #1 ·
I hope someone will be able to give me some adviceI have a Panasonic plasma, model 50PX60U, that I bought almost 3 years ago. I am generally pleased with the performance, but I've always had the feeling that the black level wasn't what it should be (no proof, just a hunch). A few months ago I bought an Eye-One Display LT and started doing some tweaking/measuring with ColorHCFR and AVS HD 709. I noticed that my measured light output for a 0% black pattern is somewhere around 0.042 ftL. I've tried everything I can think of to get it lower, including the following:
  • Lowering the Brightness setting in the user menu
  • Lowering the PCT-ADJ BRIGHT setting in the service menu
  • Lowering all the R, G, B CUTs in the WB-ADJ
  • Switching between "light" and "dark" Black Level setting in the user menu
  • Switching to Cinema or Vivid mode, and then lowering the Brightness in the user menu


No matter what I try, the black level never goes lower than about 0.042 ftL. (I'm using HDMI from my PS3, but the source device and input don't matter I get this same measurement when the TV is on and set to an inactive input). I've seen a few other posters and professional reviews that claim a black level of around 0.012 ftL for the PX60U series. I know that there will always be variations in individual sets, test equipment, etc., but to have a measured black level 3.5 times higher on my set doesn't seem right to me.


Any ideas of what else I could check? I am very comfortable navigating the service menu.


Thanks!


P.S. I've attached a recent calibration file, so you can see the 0% black measurement of 0.042 ftL. (I haven't spent too much time on the grayscale yet, I'm first trying to figure out what's going on with the black level.)

 

50PX60U_After02_HD_Standard_Warm.zip 0.982421875k . file
 

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I'm not sure what to tell you, but here's what I suspect. I would guess that there is probably a difference in instrumentation and/or technique. Using an Eye One Pro on my 42PX60U, my last couple of runs of calibration have yielded black levels of .035 ftL and .042 ftL. I also had one that measured .018 ftL. I highly doubt that my calibrated picture level really varies that much, I'm guessing it has more to do with my technique or the dark level calibration of the sensor, or any one of a hundred other variables. I could be wrong, but that's my hunch. Personally, I don't find my black level to be overly bright--although my gamma is a little on the low side, which makes images sometimes appear washed out. I'd be interested if other people have some ideas.
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by drrick /forum/post/15548185


I'm not sure what to tell you, but here's what I suspect. I would guess that there is probably a difference in instrumentation and/or technique. Using an Eye One Pro on my 42PX60U, my last couple of runs of calibration have yielded black levels of .035 ftL and .042 ftL. I also had one that measured .018 ftL. I highly doubt that my calibrated picture level really varies that much, I'm guessing it has more to do with my technique or the dark level calibration of the sensor, or any one of a hundred other variables. I could be wrong, but that's my hunch. Personally, I don't find my black level to be overly bright--although my gamma is a little on the low side, which makes images sometimes appear washed out. I'd be interested if other people have some ideas.

Thank you for taking the time to post. It's interesting to read you've had a measurement as high as mine. I'd be curious to see what reading I would get on someone else's PX60U plasma with my Eye One, or what reading another Eye One would get on mine.


This is entirely subjective - but I feel like my black level has risen over time. I wish I had bought the Eye One years ago and tested it...
 

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I don't use HCFR so I couldn't open your file; but if you figure 42 ftL for 100% white, that translates to an on/off CR of 1000:1, which is pretty normal. I typically get around 1200-1300:1 CR on 3 year old Panny plasmas, and that's with a couple different meters. One meter I used is the Milori Trichromat-1, aka Sencore CP III, and that meter is very stable and repeatable at low light levels.

Meter's absolute luminance readings can vary quite a bit. The Spectroradiometers like the i1Pro or better are very accurate at mid to bright luminance levels, but they are often flaky at low light under 1 ftL. On the other hand, the colorimeters are more accurate at low light and more consistent with ratios, but are less accurate in absolute terms. So, if the other posters are reporting wildly different numbers than you, it could be that either a) they used a spectroradiometer which is not very accurate measuring low light levels, or b) they used a colorimeter which can vary widely in luminance readings from your unit. Also, what drrick said is very true; a bad dark reading or too much ambient light in the room while measuring can cause strange results.

In short, I think your number is believable and your plasma is not unusual or defective.
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by Chad B /forum/post/15550032


I don't use HCFR so I couldn't open your file; but if you figure 42 ftL for 100% white, that translates to an on/off CR of 1000:1, which is pretty normal. I typically get around 1200-1300:1 CR on 3 year old Panny plasmas, and that's with a couple different meters. One meter I used is the Milori Trichromat-1, aka Sencore CP III, and that meter is very stable and repeatable at low light levels.

Meter's absolute luminance readings can vary quite a bit. The Spectroradiometers like the i1Pro or better are very accurate at mid to bright luminance levels, but they are often flaky at low light under 1 ftL. On the other hand, the colorimeters are more accurate at low light and more consistent with ratios, but are less accurate in absolute terms. So, if the other posters are reporting wildly different numbers than you, it could be that either a) they used a spectroradiometer which is not very accurate measuring low light levels, or b) they used a colorimeter which can vary widely in luminance readings from your unit. Also, what drrick said is very true; a bad dark reading or too much ambient light in the room while measuring can cause strange results.

In short, I think your number is believable and your plasma is not unusual or defective.

Thanks, that's good to know about the two meter types having different strengths and weaknesses.


Unfortunately, I'm not getting a contrast ratio that high since about 20-25 ftL at 100% white is all my eyes can stand (and my plasma starts buzzing loudly on bright scenes).
 

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Sorry to barge in on your thread, but I have the same concern on my 42PX75U. I don't have a luminance meter, but I took some pictures with a mediocre digital camera to demonstrate that, no matter how far down I turn down the user-level settings, my TV's black level is still brighter than my computer LCD's. The LCD is a Dell 1905FP if that matters. I think the plasma should have a better black level than this. What do you think?

 

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Discussion Starter · #7 ·

Quote:
Originally Posted by Blerghass /forum/post/15568105


Sorry to barge in on your thread, but I have the same concern on my 42PX75U. I don't have a luminance meter, but I took some pictures with a mediocre digital camera to demonstrate that, no matter how far down I turn down the user-level settings, my TV's black level is still brighter than my computer LCD's. The LCD is a Dell 1905FP if that matters. I think the plasma should have a better black level than this. What do you think?

Hmm...it does look a little bright in comparison to your LCD. Have you calibrated the black level at all?
 

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Quote:
Originally Posted by AVSman /forum/post/15579678


Hmm...it does look a little bright in comparison to your LCD. Have you calibrated the black level at all?

I calibrated with DVE, but I think this is a separate issue. It seems strange to me that the minimum luminance of my plasma is greater than that of this mediocre computer LCD. Turning down the picture and brightness or changing modes doesn't seem to help. Any other ideas?
 

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get a Kuro!



seriously, none of this is abnormal. that photo you took looks like my 10UK, my friend's 9UK, my old 600U, my friend's 75U, etc. in the dark they are going to "glow" dark gray slightly. I don't think a small computer monitor is a fair comparison.


I typically get readings from .35 to .50 ftL for the "0%" window on Panny plasmas (with HCFR + eye one D2 LT probe). I suspect the i1D2 probe just isn't particularly accurate down there. the newest 80/85/800 panny's have noticeably better black levels than the last couple of gens.
 

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Quote:
Originally Posted by batpig /forum/post/15614570


get a Kuro!



seriously, none of this is abnormal. that photo you took looks like my 10UK, my friend's 9UK, my old 600U, my friend's 75U, etc. in the dark they are going to "glow" dark gray slightly. I don't think a small computer monitor is a fair comparison.

Really? I had figured that computer LCD monitors weren't designed to produce great black levels, and that my plasma would be darker at minimum luminance. Where does my logic fall apart here? Shouldn't my plasma produced better blacks than most non-LED LCDs?


I don't have access to a luminance meter or another unit of the same model. Can you think of any other things I could try to see if my minimum luminance is in the proper range for this model?


Thanks for your response and your reassurances.

Quote:
Originally Posted by batpig /forum/post/15614570


I typically get readings from .35 to .50 ftL for the "0%" window on Panny plasmas (with HCFR + eye one D2 LT probe). I suspect the i1D2 probe just isn't particularly accurate down there. the newest 80/85/800 panny's have noticeably better black levels than the last couple of gens.

P. S. Is there a reason why your luminance readings are about a factor of 10 higher than those posted earlier in this thread?
 

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of course there's a reason, I forgot a to put in the "0"!
I meant "0.035 to 0.050" of course.


I think it's easier to get better black levels from a small computer monitor, the backlight isn't nearly as strong for something that small. LCD black level also isn't that horrible when on axis, it's off axis where it deteriorates.
 

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Quote:
Originally Posted by Blerghass /forum/post/15619096


Thanks for your quick responses. Any ideas on other methods of determining if my minimum luminance is abnormal or not?

I thought of one idea. batpig, if it's easy, could you check the minimum luminance of a computer monitor LCD you have? Do you have anything similar to a 1905FP?
 

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I'm a little out of my element as I'm no expert here
I was just reporting that the minimum luminance readings you were getting with i1D2 + HCFR were normal for Panny plasmas.


But, honestly, the black levels on the px75 just aren't THAT good. I'll see if I can test a small LCD monitor... I only have laptops at home but that should work.


Is that second photo you attached way overexposed? That definitely doesn't look normal. The first photo however looks pretty normal to me for a Panny plasma from the past couple of years.
 

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Quote:
Originally Posted by batpig /forum/post/15622950


I'm a little out of my element as I'm no expert here
I was just reporting that the minimum luminance readings you were getting with i1D2 + HCFR were normal for Panny plasmas.


But, honestly, the black levels on the px75 just aren't THAT good. I'll see if I can test a small LCD monitor... I only have laptops at home but that should work.

I haven't actually made a luminance reading on my PX75U. That was somebody else on PX60U.
 

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Quote:
Originally Posted by batpig /forum/post/15622950


Is that second photo you attached way overexposed? That definitely doesn't look normal. The first photo however looks pretty normal to me for a Panny plasma from the past couple of years.

Yes, I think you could consider the second photo overexposed. I don't know much about photography, I just set my point-and-shoot camera to ISO 50 and ISO 400. I didn't think that these pictures would provide any information about the absolute luminance, rather only the luminance of one display relative to the other.
 

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Discussion Starter · #17 ·
I can take a reading of my Dell monitor for comparison (I think it's a model 2007WFP). That would be interesting to see...same Eye One, same user (me), etc. I'll try to take a reading this weekend and I'll post it here.


I would be very interested in getting an accurate reading on my plasma with a luminance meter...I don't suppose they are cheap.



Oh, and I knew someone was going to say, "get a Kuro!"
 

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Quote:
Originally Posted by AVSman /forum/post/15628276


I can take a reading of my Dell monitor for comparison (I think it's a model 2007WFP). That would be interesting to see...same Eye One, same user (me), etc. I'll try to take a reading this weekend and I'll post it here.

Thanks! It's up to you, but it might be worthwhile to check horizontally and vertically off axis to see how the luminance varies.
 

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Discussion Starter · #19 ·
OK, I'm sorry it's taken me so long to post...


After calibrating the black level on my Dell LCD monitor, I took some measurements with the same EyeOne. I got results in the 0.046 to 0.056 ftL range, and I would say that matches what my eyes tell me (that the black level on my 50PX60U is slightly better than my Dell LCD monitor).


I guess I'll just have to buy a KURO (before they're gone!)
 

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Quote:
Originally Posted by AVSman /forum/post/15815165


OK, I'm sorry it's taken me so long to post...


After calibrating the black level on my Dell LCD monitor, I took some measurements with the same EyeOne. I got results in the 0.046 to 0.056 ftL range, and I would say that matches what my eyes tell me (that the black level on my 50PX60U is slightly better than my Dell LCD monitor).


I guess I'll just have to buy a KURO (before they're gone!)

Thanks. This is consistent with what I've noticed, which is that the black levels are close between my LCD monitor and my plasma. I will probably take a look at my roommate's 2005FPW some time, for better comparison to your monitor.


Was this measurement taken straight on? (Not off axis)


By the way, I heard the eye one isn't accurate below 1 fL. Also, I really want a Kuro now!
 
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