New developments in video displays are cropping up almost faster than we can keep up with them. Many have been exclusive to flat panel LCD and plasma sets. The once-dominant rear projection models are now relegated to the low end of most manufacturers' lines. Yes, there are RPTVs with dynamic irises, LED backlighting, and creative color adjustments, but these refinements are usually reserved for the few high-end models still on the market.

Panasonic, however, is now the first company to market with a new type of projection lamp for its RPTV sets, called LIFI. This lamp is now used in a new six-model line of popularly priced rear projection LCD sets, three of them 1920x1080, the others 1280x720. The smallest of the 1920x1080 models is our subject here, the PT-50LCZ70 at just $1,699.

Inner Light
Developed by LUXIM, LIFI is short for LIght FIdelity. Unlike the lamps traditionally used in rear projection sets, a LIFI lamp has no electrodes to fade or burn out. Therefore, it's claimed, it might well maintain its brightness for the life of the set— possibly never needing replacement. It's also said to be cheaper and easier to implement than the LED backlighting that's being used in a few Samsung sets.

A LIFI lamp is said to allow for faster turn-on time—about 10 seconds. I did not find it to be quite this quick, but more like 20 seconds. Nevertheless, that's significantly better than a conventional projection lamp.

There are three HDMI connections (one with L/R inputs for separate audio), two component inputs, and an SD card slot for viewing digital pictures.

The set also has EZ Sync, which provides for unified control of HDMI-connected components. Most manufacturers provide a similar feature in the latest sets under a variety of names. Whether or not it will work when you mix-and-match brands is something of a shot in the dark. This feature was not tested for this review.

The only obvious omission is the lack of any PIP or POP options. The set's audio quality is about average, but listenable.

The Just and H-Fill are horizontal stretchy aspect ratio modes designed to fill the 16:9 screen with 4:3 material. H-Fill is not available with 480i or 480p, and 4:3 is not available with 720p, 1080i, or 1080p—which could be an issue if your set-top box is set to upconvert standard definition programming to any of these formats. In that case, you won't be able to view standard definition program material without stretching, cropping, or both.

There are three operating modes: Vivid, Standard, Cinema, and Custom. All of these may be individually adjusted by the user, but only Custom allows separate picture settings for each input.

The set will not properly display a 1080p/24 input signal. It will show it, but reduced in size and pushed into the upper left hand corner of the screen.

All the important adjustment and operating controls are accessible through the remote control and the on-screen menus. The remote can control three other components besides the TV. The important buttons are large and easy to find in the dark, which is fortunate since it's not backlit.

One ergonomic glitch that I've seen in previous Panasonic TVs is also present here. A "Normal" control on many of the on-screen menus is actually a reset control. Select it and press enter and the items on that menu are automatically returned to their factory settings. Since it's confusingly named, resets the settings with no "are you sure" warning, and, worst of all, sits on the top of each menu, it's easy to select by accident, wiping out your carefully performed setup preferences. Beware.

Performance
The Panasonic's main strength is its excellent resolution over HDMI and good resolution on component (except at 720p). This is a fine result for what is, in today's market, a bargain big screen set. While it isn't quite as subjectively sharp looking as some set's I've tested on a one-pixel sharpness pattern with its Sharpness control on minimum—technically, the best setting—you can push this to -20 without incurring the full wrath of the edge enhancement gods. Even at -30 no one could call the Panasonic soft, and at -20 good HD program material was always beautifully detailed.

While out of the box the Panasonic's color temperature is higher than desirable even in its Warm setting, that's still the only setting you should use even if you don't choose to have the set fully calibrated.

When I performed a calibration using the coded service menu (the Pro Setting sub menu does offer high and low level adjustments for blue ands red, but not for green), I initially obtained reasonably good results. But the result turned out to be unstable, with the measurements sometimes zeroing in nicely on D6500, but jumping to around 7400K at other times—without me making any additional adjustments that should affect color temperature. For more details on this, see "Measurements."

Nevertheless, even with this odd instability (which was less obvious in viewing normal program material than you might think) the Panasonic's color, after calibration, was good. Flesh tones could look a bit warm, but never objectionable, and greens were actually more neutral looking than I expected given the set's slightly too wide color gamut (again, see "Measurements").

The Panasonic's 480i-to-1080p video processing was generally good with either component or HDMI, apart from a few tests on which it was merely fair (the Jaggies 2 and waving flag tests on the Silicon Optix HQV Benchmark SD DVD). Its 1080i-to-1080p deinterlacing (as indicated on the HD HQV Benchmark HD DVD) was fair, and like most sets we've measured to date the Panasonic does not recognize 3/2 pulldown in a 1080i source.

But there was a serious issue with the Panasonic's reproduction of blacks and dark grays. There is no polite way of putting this: they were simply poor. Nearly an order of magnitude worse than the blacks I measured in a recent review of one of Panasonic's latest flat panel plasmas (admittedly somewhat more expensive than this PTV).

The net result of the set's combination of respectable color, excellent resolution, and poor blacks is a set that sparkles on the brightest images. The set is in its element with (daytime) sports and other inherently bright, punchy program material. But as soon as the average picture level of the images drops to the mid-brightness range and below the picture turns progressively more faded and two-dimensional, with increasing visibility of the "gray fog" that's typical of inferior blacks. The bright scenes in Dante's Peak (HD DVD), for example, looked fine. But when the scenes in that movie turned dimmer, with less intrinsic contrast, the Panasonic's image degraded dramatically. None of the Panasonic's controls or optional settings could significantly improve this situation.

As is often the case in a display that cannot reproduce convincingly deep blacks, dark scenes with bright highlights on the Panasonic could sometimes appear acceptable at first glance. There's a clip from a Nine-Inch Nails concert on a recent Dolby Demo disc (HD DVD and Blu-ray—to my knowledge the Dolby disc is not publicly available but Nine Inch Nails' live Beside You In Time is available on both formats). It's very dark, but relieved by bright highlights as the stage lighting plays against the performers. Because of these highlights, the image on the Panasonic looks acceptable on such material and doesn't immediately strike you as washed out. But if you look carefully at the black areas of the picture, particularly in what should be a solid black background, you'll easily see that those areas are a medium gray and nowhere near the inky blackness they should be.

Two other problems also intruded. The most serious was a pair of narrow, horizontal bands that ran across the center of the screen from left to right. I first noticed them when checking the set's (acceptable) color uniformity with full screen white fields at various brightness levels. The bands were most visible in the mid-brightness region. They were bright enough to be clearly visible on images with solid swaths of solid color or white, but were often masked by more complex scenes.

There was also a noticeable misconvergence at the very top of the picture, with slightly displaced reds that were visible mainly on a crosshatch test pattern but never obvious on normal program material.

Conclusions
The Panasonic's fine resolution would do justice to many sets at two or three times its price. If the rest of its performance were up to that level it would easily earn a recommendation. Panasonic is also to be commended for being the first to come to market with a new, potentially revolutionary lamp technology.

Unfortunately, however, there are issues here we cannot ignore. The most serious is the set's black level. You can get far better black and shadow detail performance in many flat panel sets, including Panasonic's own. These models carry street prices not much higher than this one.

The equation changes when you jump to larger sizes, particularly 60" and above. Then the alternatives become much more expensive. The 61" equivalent of this set, the PT-61LCZ70, is thousands of dollars less than most 60" flat panel displays. We have not looked at that model, so cannot comment on how it might compare with its smaller brother. But if you are considering it, I strongly recommend that you check it very carefully in the store for signs of the problems I experienced with the PT-50LCZ70, particularly its performance on difficult, darker scenes.

Highlights
•Good, but not excessive brightness
•Fine resolution
•Low price