Yea I know this can be a bit confusing.
Rtings saying that the LG has no judder (they might mean with what ever motion effects are turned on to make it smoother during pans or movement.) That effect at least to me makes it look like something was shot on video (30fps) rather than film or video shot at 24fps. However I do understand what they mean when they say "motion is less fluid at low frame rates than the Kuros." That is simply what 24fps sources look like, however from what you wrote down I read it as saying the effect is more noticeable on the OLED. Let me explain...
The Kuros play each frame three times (just like what happens when film is being ran through a film based movie projector.) In other words, the Kuros have a refresh rate of 72hz. The LG has a refresh rate of 120hz (plays each frame five times.) The end result is both types of displays do not have to perform any pulldown to properly play back 24fps content. (Just so you know, I don't know what the refresh rate of cinema digital projectors are.)
Each type of display does not have to do any pulldown to properly play back 24fps content. What is different about the two displays types; is plasma reacts differently when compared to how OLED technology reacts when emitting light. Now here is where I get a little confused
; one of those two types when emitting light responds quicker than the other. I think it's the plasma that decays (goes to black) slower when compared to OLED. When that happens, our eyes see the light as being more persistent when compared to how our brains perceive light coming from a OLED. So that slower decay gives a perception of smother (even with judder) when compared to something that turns to black much faster. When the OLED turns to black faster, it's easier to notice the small movements that each frame create (what was actually captured on film.)
To combat that effect, OLED manufactures have turned to motion enhancers to smooth the effect of the more noticeable judder. The problem is most of these features (not all) makes 24fps material look too smooth and it all ends up looking like something shot on video.
Then there's BFI (Black Frame Insursion) used (or will be used) on some flat panel displays. From what I've read, "It simulates CRT flicker, which is necessary for the human eye to perceive fluid motion."
The point being is CRT and Plasma reproduce movement in a way that looks more like what we would see at a movie theatre playing back 24fps content. OLED manufacturers I think are still working on getting that look that people are used to. It's close, but the way it is now for some it's bothersome, and for others it's simply not anything they notice or get used to.
I have a Kuro, and I have not seen that effect you mention where the image appears to jump backwards during slow pans. I know the effect your talking about and I've seen it before, but that happens on a display that can't properly do 2:3 pulldown when playing 24fps movies sourced at 60hz like on regular TV channels. By the way that effect is called Stutter.
And in my opinion, my Kuro does have the smooth blurred look like what I see in the cinema. But again, that's simply my point of view.
Originally Posted by RichB
These terms or not well defined. For example Rtings reviews rate the LG as no judder but in fact motion is less fluid at low frame rates than the Kuros.
To avoid confusion, the Kuro (Pure Cinema mode and not 60 Hz) and to a larger extent the LG OLEDs display an effect where the image appears to jump backwards during slow pans, even though, in reality, it does not. This does not occur in the cinema's I go to. The image blurs but does NOT jump.
IMO, the desired panning motion is not the Kuro, it is the smooth blurred look in a cinema.
Frame interpolation can sharpen slow pans which is not cinematic while reducing the jumping effect, so you have to pick your poison.