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Showdown at the DLP Coral...
LCD, DLP, CRT - which projector runs the wild west?
by Max Christoffersen
September 2001
NEC LT150 DLP projector. $12995
This
was going to be a showdown. In the past 10 months I’ve enjoyed the
luxury of seeing first-hand some of the current best of the crop of HT
projectors ranging from the Sony VW10HT
and NEC540 LCD units to the CRT-based Barco
Cine 7.
But the real buzz in HT circles is DLP. Digital Light Processing (DLP) is a new and fast growing projection technology. Developed by Texas Instruments, (DLP) uses hundreds of thousand of tiny mirrors (!) instead of pixels to produce an on-screen image. Each mirror (less than one tenth the diameter of a human hair) is loaded on a semiconductor that reflects light onto the screen.
This new digital approach also minimises some of the problems of other projection platforms. Unlike CRT there is no convergence to worry about and unlike LCD there is no visible pixel lattice structure. A combination of the strengths of both CRT and LCD projection perhaps?
So a showdown it was - how good is DLP? To answer that, let’s define what we want to see.
Typically, CRT has superior black rendition and a more film-like image overall than its digital counterparts. Depth of field and natural looking skin tones and colours are a hallmark of quality projection. And a real point of difference is contrast ratio; the difference from deep black to white light. A typical CRT contrast ratio is 1000:1 - typical LCD is 400:1 while the NEC LT-150 has 800:1
So the smaller than pint-sized NEC 150 DLP arrives to have its say.
Did I say it was small? It is smaller than the screen you are looking at right now. If you are looking at a CRT based computer screen, chances are the NEC 150 could fit inside it!
The LT-150 also features:
-
A credit-card sized remote and very intuitive on-screen menu;
-
Selectable standard 4:3 and 16:9 screen ratios;
-
A low but very adequate 800 ANSI lumen light output;
-
A native resolution of 1024x768
-
Selectable white segment (turn it off)
So the showdown begins. Setting up was a snap, but LT-150 has no zoom, only a focus control, so positioning relative to the screen is crucial. It does however have keystone control and a wide range of image controls including Gamma and individual colour controls for RGB.
So how’d it look? First up was a composite DVD/TV image and the image looked soft and lacking dynamic impact. I suspected things may change with a high gain screen and my Toshiba Progressive Scan 5109 DVD player as a source.
So with A Bug’s Life and my high gain (4:1) Draper screen ready, the NEC was fired up again. And very suddenly the ‘wow’ factor was there. I mean WOW! Gob smacked, jaw dropped and bowl me over - wow!! In particular the "Where’s My Food" underground scene has dark blacks with high contrast images almost side by side.
And the colours were simply eye candy! Glorious! And with such delicate detail (ever noticed the dimple's on Flick’s head?) and add in the blue of these scenes and you have a tricky task for any projector to handle. And while it still failed the real black test (see NEC 540 sidebar), the deep space scenes on Starship Troopers were the best I had seen from digital projection.
The fan noise was high from such a small box, but all things considered, the first night’s viewing had me conceding defeat: CRT is an endangered species and DLP is going to knock it off.
Spinning colours - the DLP Rainbow Effect |
|
The DLP 'rainbow' is a visual effect unique to DLP projectors. The rainbow appears as a prism 'after-image' or colour streak, that viewers notice for a millisecond when changing focus from one part of the screen to another. It appears as a ghost-like image that can't be seen directly, but is at the edge of the viewer's peripheral vision. Reading on-screen credits or sub-titles can also result in viewers seeing the rainbow artefact. Curiously, some people appear more sensitive to it than others. And some films, high gain screen types and processors appear to accentuate/minimise the effect. There is no consistency with the DLP rainbow other than it appears to be more prominent with single chip DLP projectors and with the early colour wheel models that rely on slower processing speeds of the video signal. The slower processing speed allows the eye to 'catch-up' and synch to the digitally constructed image and in doing so, effectively deconstructs the on screen image into its primary colours. More expensive and sophisticated 3-chip DLP units appear to be minimising if not totally eliminating the effect, but it remains an anomaly (like TV screen 'flicker') that some people appear to be more sensitive to than others. As with any projection type there are compromises (CRT - convergence, LCD - pixel failure) to live with and the DLP rainbow appears as an unusual if very visible projection issue to consider before making a final purchase decision. |
Day 2 with DLP dawned. And then I saw it. My first rainbow.
I didn’t know what it was at first. But on Terminator 2's dark scenes (‘Take a hike Bozo..’) had prism like after-images that were imaging on straight lines whenever I moved my focus from one side of the screen to the other.
Some people aren’t affected by this DLP on-screen artefact, and some people are.
Other factors to consider are a high fan noise and 1000 hour life of the bulb. At $800 a bulb, that running cost is climbing towards 80 cents an hour.
But all factors considered, DLP was a revelation. And it is very easy to say that digital projection is the way of the future for home theatre projection.
But see it - before you buy it. The colour, and detail are all very seductive and the set-up and size convenience are sure-sellers.
The only question really is: are you among those that see the DLP rainbow? If you are lucky enough not... Buy it!
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