Panasonic LCD / LED Backlight Dimming /Fluctuation Problem

Discussion in 'Panasonic TVs Forum' started by Judesman, Aug 25, 2012.

  1. Judesman

    Judesman
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    I have a new Panasonic LCD TV Model TX-L32ET5B (In the UK). In some programmes in scenes with dark lighting the picture fluctuates between dark and very dark to the point where you can not see much. This only seems to happen with dimmly lit scenes, in HD as well as standard definition. The shop tried a new TV but the same happened (This however was seen by the technician from a recording of the problem I had made on a DVD recorder). The shop took this up with Panasonic and they say it is not a fault but the way their new models work trying to display a perfect black! They also say that all makes of LCD TV will display the same problem. If I watch these problem programmes on the computer the pictures display perfectly. The problem is worse with C.A.T.S. OFF. I find this very annoying and the shop has offered to take back the set in exchange for a 42" Plasma but the room is very light and 42" is too big really. Any thoughts please?
     
  2. grnicol

    grnicol
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    Hi,

    Firstly you are not alone! :D

    I too have a new Panasonic LCD TV Model, the TX-L37ET5B.

    What you are seeing is the dynamic backlighting that Panasonic have implemented and as you have noticed, in some programmes in scenes with dark lighting the picture fluctuates between dark and very dark to the point where you can see virtually nothing!

    It does seem to happen with dimmly lit scenes, as they lower the backlight to enhance the black, but it's too aggressive!

    "The shop took this up with Panasonic and they say it is not a fault but the way their new models work trying to display a perfect black!" I can believe they said that.

    They also say that all makes of LCD TV will display the same problem. Not sure I believe them on that point, but all LED tvs try various ways of improving black levels, with local dimming etc. The degree and controllability of such methods varies.

    As you have noticed, with CATS set to "on", this reduces the degree of reduction to darkness, as the "environmental" contrast / lighting control seems to win out!

    It is VERY annoying. However, (and here's the good bit!) try the True Cinema Mode - the dynamic backlight does not function in that mode, so no clamping down of blacks whatever the scene being displayed.

    I'm also thinking of going the (42GT50) Plasma route but be aware Plasma brings another set of issues/features from what I have read; but I'm only considering this as I have a light bleed issue as well....really annoying when watching films in subdued lighting....otherwise I'd stick with True Cinema as I prefer that mode anyway.

    HTH. Let us know how you get on.
    :smashin:
     
    Last edited: Aug 25, 2012
  3. Judesman

    Judesman
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    Hi grnicol,

    I am pleased to hear that I am not the only one. When Panasonic said that there is not a problem I didn't really know whether to believe them especially as the shop said that no-one else had reported the problem. It is annoying and I seem to be very aware of the problem now. I have trawled the internet and cannot find anything about this so I am pleased that you have responded.

    The shop has offered to replace the set with a plasma and suggested the TX-P42ST50B (I have to pay the difference in price). There are some good reviews on the internet but I have quite a light room and I understand that this might not suit a plasma and 42" is too big for the room really.

    I could ask the shop to exchange for a Samsung LCD. I now understand that these are better than Panasonic but I have a Panasonic DVD recorder and the VIERA LINK works well.

    I will try the True Cinema Mode and report back.

    Many thanks for your input, that is appreciated.
     
  4. luggsie

    luggsie
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    Glad someone else has the problem. I have a TX-L42E5B and find the screen modes "cinema", "true cinema", "game", "dynamic" a bit meaningless. Usually "dynamic" is crisper and brighter than "cinema" as I believe it should be, but on some source material it is the other way round so I'm always digging around in the menu to get a good picture.

    I haven't worked out what "true cinema" is doing yet, it only seems to put a bluiish tinge on "cinema".

    A tad unsatisfactory for a leading manufacturer.


    luggsie
     
  5. grnicol

    grnicol
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    Hi Both :)

    Do try True Cinema - This should not re-process the picture (in theory). Also, switch off the noise reduction (P-NR)option, switch off the overscan and Intelligent Frame Creation (Advanced Settings) and maybe tweak the colour setting down to taste (my first set didn't need this but the second was too "colourful"). I have left the sharpness and brightness alone.

    You won't get the dynamic backlight at all in True Cinema and can still use CATS in that viewing mode if the room is "light", but I'd leave it off when watching in subdued or dim room lighting as the contrast drops too much to compensate.

    To remove "blue tinge" change the colour balance setting to warm from cool, (cool does apply a very blue tinge to the picture). If you're in True Cinema this setting is not there and is already set and it has looked ok on both tv's I've seen. :thumbsup:

    PS: I too would like to stay with Panasonic to keep the Viera link etc. Am going to "review" it again tonight with a flm in a darkened room.
     
    Last edited: Aug 25, 2012
  6. Judesman

    Judesman
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    Hi Luggsie,

    I was going to do some more research before posting again but I have now tried grnicol's suggestion to try True Cinema Mode. I have the fluctuating blacks recorded on a "Columbo" that is particularly bad. I have set True Cinema and it hasn't made any difference so I am very disappointed. I watched "Parades End" in HD last night and there were problems with that.

    When you set True Cinema I see that it alters the contrast, brightness and colour settings. But as grnicol says True Cinema disables dynamic backlighting, but if that is the case why didn't True Cinema make any difference to this problem on my TV.

    I have spent a lot of money on a TV and DVD recorder and feel locked into Panasonic. I posted a review on the Panasonic website and gave this TV one star. Panasonic will not post the review but at least they will know what is going on.

    I really do not know where to go from here.

    Judesman.
     
  7. Judesman

    Judesman
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    Hi Grnicol, I will try your further suggestions and report back.

    Judesman.
     
  8. grnicol

    grnicol
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    Hmmm, I'm surprised True Cinema is still allowing the dynamic to work. My 2nd (current) tv went through a software update when I first switched it on the other day. My software version (setup > system menu > System Information) is 1256-10302 - may be worth comparing?

    As a thought, could the shop try playing the recording through another make of tv such as a Sony...Plasma isn't the only other option, if you are otherwise happy with LCD? As I mentioned before, Plasma doesn't come issue free and an extra 10" on the screen diagonal isn't insignificant if 32" is the right size for the room - not to mention your extra cost?

    Very disappointed that Panasonic aren't playing ball, especially not publishing your review. :mad:

    I just hope we can find a way to help you.

    Graham.
     
    Last edited: Aug 25, 2012
  9. Judesman

    Judesman
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    Hi Graham,

    I have changed all the settings as you suggested but the problem persists. With C.A.T.S. off the problem is very bad. I find with some dark scenes the brightness is constantly changing, it is very annoying. I have the current update. In every other respect I am quite happy with this TV and a 42" plasma is far too big for the room.

    The only other TVs the shop stocks are Samsung as far as I know and I wondered if anyone had experienced this problem with a Samsung LCD? But as I said I also invested in a DVD recorder so feel locked into Panasonic. I might just have to accept the problem and learn to live with it.

    I have another five year old Panasonic TV and will try playing the recording through that but I will not be around to do that tomorrow. I will let you know how I get on in due course.

    Thanks for your help.

    Judesman.
     
  10. grnicol

    grnicol
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    Hi Judesman,

    Would certainly be worth trying your recording through a Samsung and also through another ET5B set on True Cinema. The True Cinema and the dynamic backlight doing it's thing just doesn't seem right.

    I'm wondering if there is a way you can get your recording to me, so I can try it out on mine?

    Enjoy a tv-free day today! :)
     
  11. luggsie

    luggsie
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    Haven't had any problems of fluctuation within a program, but different sources seem to play musical chairs with the screen modes. Each source has its own individual setting memory of course, but every time I change sources, eg. cycling around Inbuilt FV Tuner/ Humax FV STB/ Humax freesat STB/ Sony DVD recorder/ Sony Blue Ray player all on HDMI's, I find the last used setting isn't right any more so I have to go into Menu and change the screen settings again. The best mode seems to be a random selection every time, though "dynamic" is the most consistent, but "normal" sometimes has most contrast and crisper picture. CATS is OFF after I found it just screwed things up.

    I can always get a good picture eventually but am baffled as to why it should be such hard work, especially as Panasonic have even gone to the effort of offering individual settings for each source to get round just this exact problem.

    If I can sort out why it's so unstable I'll report back !


    luggsie.
     
  12. grnicol

    grnicol
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    luggsie,

    I'm wondering if it is the different HDMI input on the tv that is creating the differences rather than the source itself? Have you tried swapping HDMI port on the tv and seeing if the differences you are seeing remain or change?
     
  13. Judesman

    Judesman
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    Luggsie, I thought from your initial post that we had the same problem, that is the fluctuating backlight that in my case makes the picture quickly jump around from dark to very dark. I have noticed that when you change the mode from Normal to True Cinema it also changes the contrast, brightness and colour.

    Graham, this is really weird! First of all I played my problem DVD recording through my old five year old Panasonic and there is no problem so it must be the new set that is at fault (As expected). Previously changing to True Cinema did not make any difference but I have tried again this morning in True Cinema and the problem DVD played perfectly. This is all very odd because when I watched some drama, live so to speak, over the weekend I had backlighting problems. The other problem is that I don't really like the True Cinema mode as it seems to make the picture a bit soft (not so sharp).

    I happened to notice that if I change the mode to True Cinema in a recording on the DVD recorder it changes the mode for every recorded programme on the recorder.

    When I first complained to the shop about the backlighting problem, they brought a new ET5B but the recorded programme displayed exactly the same. Thank you for your offer but technically I wouldn't know how to get a copy of the recorded problem programme to you and I think I have proved that it is a problem with the Panasonic model. I am suprised that more people have not complained about this but I think I will just have to live with it.

    Thanks for your help.

    Judesman.
     
    Last edited: Aug 27, 2012
  14. grnicol

    grnicol
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    Hi Judesman,

    I'm glad it played correctly in True Cinema - it's easy to think you've selected a viewing mode sometimes, but have in fact exited without changing it - been there, done that :D

    You can still tweak settings in True Cinema mode of course to counter the seemingly "dull" picture, but bear in mind the Normal and Dynamic can be a bit too bright/colourful and we need to adjust to different viewing settings.

    I would live with TC for few days and I think you will find it's not as dull or strange as it seems to you at present.

    This mode really is more realistic in terms of colour, colour temp, brightness etc, but you can tweak it if needed (except for the colour temp). All I've done is knock the colour down 6 notches.

    Do persevere :) we need to adjust to what we're now seeing. Hopefully you will be happier with it in a few days time.

    Keep in touch and let me know how it goes.

    Graham.
     
  15. grnicol

    grnicol
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    Judesman,

    I'm not sure if I'm understanding this correctly but, you can only be in one viewing mode at anytime. So selecting a mode (e.g. True Cinema as per your example above) means the tv will be in True Cinema mode for all other viewing, be that off-the-air or a recording, until you change the viewing mode again. It doesn't latch onto specific recordings.... I've probably misunderstood you, and if so, please let me know.
     
  16. Judesman

    Judesman
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    Graham, all my off-the-air programmes are set to Normal but if I press "Direct Navigator" to access the recorder all the programmes there are set to True Cinema. I can change the modes on the TV and it does not alter the mode set when watching a recorded programme and vice versa. If I change the mode whilst watching a recorded prog it changes the mode for all recorded progs but not the mode set for off-the-air progs. Are you saying this should not happen?
     
    Last edited: Aug 27, 2012
  17. grnicol

    grnicol
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    I may be confusing things....

    The viewing mode seems to be source dependent, so as you've seen, all off the air will use whatever mode is selected e.g normal, until you change it.

    All recorded material from a DVD player uses a view mode (all material from that source will use that same mode) until you change it...and then all that source's recordings will use that new mode.

    In fact, I'm now wondering if that was what Luggsie was referring to.....
     
    Last edited: Aug 27, 2012
  18. Judesman

    Judesman
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    Yes, so view settings in off-the-air and recorder act independently. Yes I think it might be what Luggsie was referring to.

    I am going to watch programmes carefully over the next couple of days to see whether I can get rid of this backlight problem before going back to the shop. They have been very good, the TV is already two months old and they have said that they will exchange it.

    The trouble is that if no-one else is noticing or experiencing this problem Panasonic will not do anything about it.

    Thanks for your help.
     
    Last edited: Aug 27, 2012
  19. grnicol

    grnicol
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    Hi,

    So long as you are in True Cinema for both OTA and the DVD you won't see the dynamic backlight doing its worst ever again. :smashin:


    Graham.
     
  20. Judesman

    Judesman
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    Many thanks, Graham.
     
  21. coops233

    coops233
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    My TV is a different model but it's a Panasonic.

    Do you have access to professional mode setting? I noticed the same problem with my blacks when watching The Dark Knight, setting was True Cinema.

    I have now switched to Professional mode 1(or 2 can't remember exactly), this has solved my problem.

    I believe it has something to do with the C.A.T.S trying to find the perfect black and is more obvious in a dark room.
     
  22. Judesman

    Judesman
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    Hi Coops, I can't find a professional mode setting. I am watching everything in True Cinema at present but haven't done much viewing over the past couple of days so there is nothing to report. In normal mode the problem is a lot worse with CATS off.

    Thanks for your input.
     

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