For some years now, BenQ seems to have been able to supply DLP home theatre projectors at lower prices than you’d expect. The BenQ W7500 is its latest top of the line model. Stephen Dawson investigates.

The BenQ W7500 is a full HD projector, offering a resolution of 1,920 by 1,080 pixels. Single chip DLP technology is used as the engine. This has been placed behind a lens capable of a 1.5:1 zoom range and with a built in lens shift.

Lens shift allows the picture to be moved across a screen without keystone distortion. This is controlled using a small joystick on the front panel. I shuddered when I first saw it as similar contraptions have in the past made it very difficult to exercise the precise control required to get the projected image accurately onto the screen. This one worked smoothly, though, and allowed excellent precision.

The zoom range of 1.5:1 combined with the lens shift capability provides good installation flexibility. To fill a 100” screen the projector needs to be located from 3.591m to 5.386m away. Among the aspect ratios permitted by the projector is one (LB) which is compatible with the use of external Panamorph lenses to stretch the image sideways – something that is useful for constant image height enthusiasts.

The 300W lamp is rated to deliver up to 2,000lm on the screen and BenQ says that the unit can deliver a native contrast ratio (i.e. without the use of a dynamic iris, which this projector does not have) of 60,000:1. Run in ‘Normal’ mode the lamp has a rated life of 2,000 hours. In ‘Eco’ mode it is extended to 3,000 hours.

The projector has the usual inputs (even S-Video, although it’s hard to see this being of any use these days), including two HDMI ones. There’s also a 12V trigger output and both RS-232C and USB connections are provided for control applications.

Picture Quality
Rare for a projector, this one defaults to full power output, which it calls ‘Normal’ lamp brightness. So one of the first things you might want to do is knock it back to ‘Eco’ level. In a dark environment on a normally sized screen this provides plenty of brightness and extends the lamp life by 50%. If you pop in a Blu-ray 3D, where the additional brightness is useful, the projector will automatically switch to the ‘3D’ picture defaults, which include full lamp brightness.

Out of the box the picture was a touch iffy. In part this was due to the ‘Sharpness’ setting being up to high. The appropriate setting is ‘0’, otherwise a harsh kind of distortion tends to create a wearying fussiness in the picture. Also consider turning down ‘Detail Enhancement’ to zero for the same reason (this is under Picture – Advanced/Clarity Control).

Another issue was that the reds were a touch too hot. Generally that just gave a healthy glow to the cheeks of the actors, but there were scenes where the reds really stood out artificially on the faces of the actors. In particular during the ‘stage’ scenes in the Blu-ray of Chicago, but also quite frequently while watching digital TV from a PVR. This, it turned out, was due in part to ‘Brilliant Colour’ being switched on in the advanced picture settings menu, and to a slightly high setting for saturation and gain for reds in the ‘Colour Management’ section of the advanced menu. Bringing both of those down to the low 50s tamed them and resulted in very natural colour.

With those adjustments the picture quality with decent source material was magnificent.

Now, if you want to get really picky, using grey scale test patterns there was a noticeable bias towards blue at around 5% black, but this had no visible effect on regular colour content and failed to draw any attention to itself, even with black and white material.

The black levels were quite deep, more than sufficiently so to allow good visibility of detail in dark scenes. This is impressive given this is due to the native capabilities of the projector, rather than the use of some kind of dynamic iris to control the light output.

That meant that there was none of the quiet chunking sound of a mechanical iris moving from position to position, nor any pumping of brightness levels.

There was a slight DLP rainbow effect that would fleetingly appear from time to time. But it was infrequent – I’d say I noticed it perhaps once per evening of viewing – and it mostly appeared when there was an unintentional sliding of the semi-focused eyes across the screen.

One of the virtues of DLP can also lead to bit of a problem. The virtue is the incredibly rapid rate at which DMD pixels can switch on and off, which is kind of odd considering that this is a mechanical process rather than a solid state one. Nonetheless, the pixels switching is for all practical purposes instantaneous, rather than in the millisecond range for LCD and LCoS projectors.

That creates a problem. During scenes in which a camera pans across a vista, or an object moves across the frame, at certain speeds ‘judder’ becomes apparent. That is a kind of step motion is perceptible to human vision as the vista or object moves in steps at 1/24th of a second. The relatively slow switching of other technologies tends to smear any judder so it isn’t quite as obvious. DLP, thanks to its greater accuracy, makes judder about as obvious as it can be.

Judder is best dealt with by a motion smoothing frame interpolation system. This works by taking two frames of the movie or whatever and calculating (interpolating) a new frame to go between them in which objects are halfway between the positions in the two frames.

This is not an easy thing to do. Although such systems have been around for around 15 years, they still tend to produce a kind of ‘heat haze’ artefact and can make movie look glossy and studio-shot.

This projector has a three level system, and the bottom level (‘Low’) turned out to be very good. The higher levels produced obvious artefacts, but with ‘Low’ there was improved clarity in moving scenes and any artefacts were so minimal that they were practically invisible.

I readily put purity in viewing the source aside, for the most part, to enjoy the cleaner image provided by this function.

While on the image processing, I should mention that as good as the projector’s motion interpolation was, its deinterlacing of 1080i50 and 576i50 – from a small number of Australian Blu-ray discs, and almost all Australian DVDs respectively – was pretty mediocre. Regardless of the ‘Film Mode’ setting, if fed these signals it treated the input as video sourced, even if it was clearly film sourced. So it employed the wrong deinterlacing strategy most of the time.

The ‘video’ style deinterlacing was pretty good, motion adaptive and all that so that maximum resolution was delivered on static parts of the picture. But unfortunate visual artefacts, such as moiré patterns and jaggies, appeared all too frequently as well.

For best performance with this projector, it’s best to feed it with a high quality progressive image, not leave it to the projector to cope with interlaced input.

Now while the fast switching speed of DLP may lead to greater perceived judder, it really offers an advantage with 3D. A huge advantage. Most 3D ‘crosstalk’ or ‘ghosting’, where one eye sees a small proportion of the content intended for the other eye, is due to timing issues. DLP can switch so very rapidly and cleanly between left and right eye views that these issues are diminished to insignificance. And that was the case with this projector.

It didn’t particularly matter whether the 3D content featured darker colour objects on a bright background, or bright objects on a dark background, there was no visible ghosting that I could detect. The result was a 3D effect that was stunning in its depth and immersion, since it left no clue of its artificiality.

Conclusion
The BenQ W7500 home theatre projector produces a high quality picture for a quite reasonable price, so long as you’re prepared to tweak the controls a little. And when it comes to 3D, it’s about as good as it gets.