I have a Panasonic plasma (1080p) and the tip below I found on a message board made an enormous difference in the SD quality. I mean huge! So, if you have a Scientific Atlanta cable box like I do you have to do this. If not, maybe there is something similar for other boxes. Also, to enter the special setup mode you have to hit the buttons on the box, not the remote.
Here is a little tip for people with this TV (I have 50pz700u) using a 8300HD DVR/cable box. This will allow as much up-scaling to be done by the TV instead of the cable box (the 8300hd has a crappy scaler). But best of all, SD channels will fill the screen by default instead of you having to change the Panasonic's Aspect or the STB's Zoom button everytime you change channel from HD to SD. This really minimizes the amount of times that I have to use the TV's Aspect button or the STB's Zoom button.
Enter the 8300HD's advanced set-up:
1) Turn 8300HD power off
2) Press Guide-Info buttons at the same time
Choose 16:9 and advanced setup. Follow the instructions to activate only 3 of the 6 resolutions:
1080i (top left option)
720p (top right)
480p Standard (bottom left)
So you should have only these 3 things in the list of display modes with green dots next to them in the STB's advanced setup. After that, when watching TV again use the STB's remote to make sure Picture setting is set on "DVI/HDMI" instead of Fixed or Upscale.
FYI, while viewing television, you can use the Recall button on the Panasonic remote to see what signal that channel is coming into the TV as. After following the above setup recommendations you should see 480p for all analog or digital SD channels, and 1080i or 720p for all HD channels.
Now whenever you change channels to an SD channel, that is a channel that is coming into your TV from the cable box as 480p, the SD channel will automatically default to the "JUST" Aspect ratio on the Panasonic. The image will fill the screen without any side-bars and without cutting things off the way the Zoom modes cuts things off.
HD channels, that is channels that are coming into your TV from the box as 1080i or 720p will of course will default to the "FULL" aspect ratio.
Now the only time you will see sidebars is when an HD channel is displaying 4:3 content material.
And the SD channels look fantastic being upscaled by the TV and displayed in the JUST aspect ratio. Especially if the SD channel is being broadcast digitally. Sometimes I find myself using Recall just to confirm that it's really only SD since the picture looks so good. If your SD channels look crappy, chances are they are analog SD channels and you have a not-uncommon crappy signal.
I learned this trick from a Cable TV technician who came to my house to troubleshoot a bad signal. He saw I had all the green dots in the advanced setup on and he goes, "I can fix this so it will almost always fill the screen, and this will be better". And he did. And it is!
ps: I have my stb hooked up via HDMI don't know if this will work otherwise.
Edit: Just confirmed that it's not that the TV defaults to JUST in 480p, instead the TV remembers what display mode you're in for 480p. So if you follow my Advanced Setup recommendations then set a 480p channel to FULL it will be FULL when I switch to any 480p channel. If I set to JUST it will stay JUST for all 480p channels. It was just coincidence I had 480p at JUST which is what I like anyway![]()