Backlight inconsistency, which was a major problem on the 55LW650T, is much reduced on the 42LW550T. The edges and corners of the picture exhibit more or less the same level of brightness – or rather, darkness - during dimly lit sequences as the rest of picture and there are no distracting pools or patches of extra brightness. This makes the smaller screen's pictures immediately more involving and natural.
A more surprising improvement in backlight consistency comes from the 42LW550T's local dimming function. On the 55LW650T this tended to throw up ugly misty 'chunks' of extra light around bright objects when they appeared against dark backgrounds, but these imprecise illumination 'haloes' are much less overt on the 42LW550T (provided you don't run the backlight too hard). They are still there, but much more infrequently and are only visible if you really look for them.
This is particularly important since the 42LW550T's black level depth with the local dimming engaged (even on the Low setting) is much better than it is with the feature off.
Having overturned the 55LW650T's backlight problems, the 42LW550T then has a good stab at overcoming its larger siblings' 3D issues. Whereas you can make out subtle horizontal line structure in the 55LW650T, especially (though not exclusively) when watching 3D, this is much less obvious on the 42LW550T. You can still see it if you stick your face right up against the screen, but of course, nobody in their right mind is going to do that.
A similar benefit of seeing FPR running on a smaller screen is that you're less aware of the resolution reduction. LG claims its technology is full HD, but this doesn't tally with the reality of watching a 3D Blu-ray simultaneously on a new big-screen LG set and a similarly large active set.
However, this 42-inch TV achieves more sharpness than you might expect considering that it's effectively sharing its full HD screen space between two images simultaneously rather than presenting full HD images to each eye in sequence. The effect is sort of a halfway house between standard-def and full HD and will probably be ample at 42-inch for mainstream viewers, especially given the advantages of the FPR system.
The first of these is flicker, or rather the lack of it. If you usually watch TV with a lot of ambient light in your room, active 3D TVs can generate a sense of flickering as their active shutter glasses open and close. This doesn't happen with the FPR approach.
The glasses are also less cumbersome and heavy than most active shutter ones and don't require any synching with the screen. The specs also reduce the brightness and colour vibrancy of 3D images less than active shutter versions.
Finally – perhaps chiefly because of the different types of glasses used – watching FPR 3D for long periods of time feels less tiring than watching active shutter 3D.
LG claims other strengths for FPR, including, most notably, freedom from crosstalk, but there are issues with this claim, not least that the very best active TVs have hugely reduced crosstalk noise recently, while there are definitely signs of it on the 42LW550T. That said, provided you watch this set reasonably square-on, crosstalk appears only rarely and is generally minor when it does.
It's interesting to note that crosstalk is more prone to appear on the 42LW550T with the 2D-to-3D conversion system in play, perhaps as a result of this making a few more depth-related errors than you might expect to see from the very best conversion engines (a crown that probably rests on Samsung's head at the moment).
It's also crucial to point out that the 42LW550T's 3D pictures break down into horrendous crosstalk if your viewing angle exceeds 10° above or below the screen. It also creeps in a little if you have to view the TV from a very wide angle to the right or left - a position that also reduces the depth effect of the 3D image. Unless you've got a particularly small room, though, you should be able to accommodate seven to 10 people around the 42LW550T reasonably well without any of them suffering any drastic reduction in image quality.
Weigh up all the pros and cons of the 42LW550T's 3D pictures and the result couldn't be more different than it was with the unforgivingly massive 55LW650T. Instead of ruthlessly exposing FPR's shortcomings, the smaller screen size shifts the focus to its strengths and by doing so makes it a fun and relatively affordable way for families and friends to get into 3D.
Colours are very good after a little tinkering with the set's tools. Tones are punchy and dynamic without any sacrifice in the subtlety of blends. Skin tones can look a fraction plasticky, but not so often or so much that pictures ever really look unnatural.
Using any of the TV's presets (except perhaps Cinema) rich reds and blues can look a little dominant, as well as suffering more noise than is ideal, but the balance issue can be resolved almost completely with a little tweaking of the colour settings, while the noise problem also calms down to tolerable levels if you rein in the contrast and backlight settings.
There's a trace of jaggedness to the edges of very bright, slightly countered objects, but this side-effect of the filter mounted on the screen is much less aggressively obvious than it was on the 55LW650T.
Rather more troubling is the 42LW550T's motion processing. Even if you turn the TruMotion engine to its lowest setting flickering artifacts are visible. Turn it off, though and the picture looks slightly juddery and suffers from a touch of motion blur.
Luckily, a partial solution lies in the way the TV enables you to adjust the de-judder and de-blur elements of TruMotion. Set these to their lowest levels, or possibly to level 2 at a push, and the artefacting is reduced, creating an acceptable balance between reduced judder/blur and unwanted processing side-effects.
Input lag is one problem for which there doesn't seem to be a solution. Our tests revealed an average delay of 114ms (varying between 100ms and a maximum of around 150ms), which proves particularly detrimental to gaming. Time-sensitive games such as Guitar Hero or Call of Duty (online) clearly suffer, producing a frustrating and unrewarding experience. Given how much else the 42LW550T does right, and its potential to be a fun way for friends to indulge in some 3D gaming, this input lag flaw (that exists even within the screen's own Gaming mode) is a real shame.