NHL 13 and P50GT50 (or any plasma, if I'm not mistaken)

Why don't use just turn the auto-brightness feature off?

The Panasonic GT50's auto-brightness setting is called C.A.T.S. and it can be turned off in the user menus. Menu -> Picture -> CATS.

Also, if you change the picture mode to Custom it will automatically turn CATS off. You'll have to adjust the picture manually from there.

Well, then whatever you're seeing isn't due to an auto-brightness adjustment. Something else is going on. Have you tried turning AGC off? Those are the only 2 settings that should automatically do something like what you're describing.

I'm not saying it doesn't have it, I'm saying that on the Panasonics it can be turned off.

"I'm not saying it doesn't have it, I'm saying that on the Panasonics it can be turned off."

You are entirely missing the point. CATS and ABL are two different things. CATS is dynamic contrast, a user adjustable setting that is intended to increase perceived contrast at the expense of overall image quality. ABL is a hardware limiter built in to prevent drawing too much amperage from the power supply, killing the power supply in the process. Auto Brightness Limiters can not be turned off by the end user.

"Just a couple of more pics, showing what I mean by ABL."

Throughout my three plasmas, I have very rarely run in to the ABL, and never after doing a proper calibration on them. I notice your Contrast is at 85, and I immediately question that. Contrast controls how bright whites are, and therefore how quickly you will run in to the ABL. On my previous plasma, which was Panasonic, I ran Contrast in the 60 range and never noticeably bumped in to the ABL. Also, what temperature mode are you running in? Warm or Normal is pretty normal, and I wouldn't be surprised to find that running in Cool makes the rather blue ice extremely noticeable in ABL moments.

Your Sharpness is also cranked up way too high. 0 is likely the "off" point, and around 15 is where you will probably find perceived sharpness improvements at viewing distance without over-sharpened artifacts. Back in post #4 you say:

"Now, I could live with the dimmer ice, but the ABL drowns out details in the players by lowering the contrast ratio. In the second shot, notice that the player lights up and details on his jersey can be more easily made out."

You'll also notice in that seconds shot that the player has a nice glowing halo around him. This is due to Sharpness being cranked up to ridiculous levels. When ABL kicks in, that halo reduces in presence leaving you with the impression that the image is less sharp. In actuality, the less sharp image is more correct, but the human visual subsystem is super-easy to trick with things like over-sharpening.

You need to go back to calibration basics, get used to a properly calibrated set, then play the hockey game. A properly setup display is a lot dimmer than people think it should be, but after a day or two of use, you'll notice that things are actually a lot more film-like and natural. You'll also notice that cranking Sharpness down to 0-15 A) reveals a lot of detail that over-sharpening artifacts hide and B) makes aliasing a lot less pronounced on the current consoles as high contrast lines now don't have a halo highlighting them drawing attention.

Go back to post #4 and look at your two images again. Look at the black circles on the white ice. Notice how in your brighter image it goes "white ice - bright white line - black line - bright white line - white ice". Look at your dimmer ABL image. Notice how it goes "white ice - faint halo - black line - faint halo - white ice". The dimmer image is still wrong, but not by nearly the degree. The game is rendering "white ice - black line - white ice". Your display should not be trying to add in detail to the rendered image. Anywhere that the display is artificially adding in sharpness like that is where the display is actively destroying detail.

Without getting Sharpness under control, you can not accurately judge anything related to detail. Once you correct Sharpness, then you can start working on correcting Contrast and avoiding the ABL.

In an effort to help further, I skimmed your post history real quick. The common thread I see is that you keep using terms like "pop" and "vibrant". These are traits that point to everything that is wrong with modern displays, as they are initially set up to look as bright and appealing next to their cheap neighbors at the Best Buy. A display set up to pop and be vibrant has little regard for an image that looks correct. My best recommendation? Calibrate for correct, hate it for a day, get used to it over a week, and then forever wonder how you've spent the last decade looking at such terrible popping, vibrant displays. "Correct" is better than "vibrant".

If you have no interest in "correct" and instead insist on an image that "pops", then return your plasma and buy an LCD. That display technology has it's own host of problems, but at least it will look wrong in the way that you want it to look wrong.

I'll end this with a little story: Every time we get a new plasma the first words out of the girl's mouth are almost always "Oh wow, it's so much brighter than the last one!". I then remind her that it's still set up to look as good as possible on the Best Buy floor, and it will be much dimmer over the next couple of days as I dial it in. That night she usually complains "Gah, this new one is way too bright. I'm going blind over here!" as it takes a couple of days to figure out exactly where I want the display to ride in it's settings.

Here's the best part. Every time she comes back from a friend's house that she has watched a movie at she talks mad-trash about their display. "Jesus, dude. It was too bright, all the shadows were bright gray, the actors were tomatoes, and everything had a blue tinge to it. It was hard to not grab the remote and start fiddling with crap to at least make it look acceptable." Yes, even people that don't care about TV settings at all vastly prefer "correct" once they actually know what correct looks like.

When a plasma's screen is showing mostly whites, they will get dimmed to gray. it's part of the tech, and no screen options can change that, though the screen shots above look terrible.