Short-throw interactive projectors like the Dell S320wi are best understood as less expensive, but nearly as good, alternatives to ultra short throw models like the Editors' Choice Epson BrightLink 485Wi. For any given size image, you can't put them as close to the screen as with ultra short throw projectors, but they generally work just as well otherwise. More important, the S320wi in particular is a reasonably capable representative of the breed.

Built around an XGA (1024 by 768) DLP chip, the S320wi offers a 3,000-lumen brightness rating, putting it in the typical range for current models meant for small to medium-size rooms. It weighs only 7 pounds, which makes it potentially portable. If you want to carry it with you, however, you'll have to buy a carrying case separately. Dell doesn't include one with the projector, which isn't surprising given that projectors in this weight class--particularly interactive projectors—are most likely to wind up on a cart or permanently installed in a wall mount.

Short Throw vs. Ultra Short Throw

Short-throw projectors have the advantage of projecting a big image from a short distance. They're not a match for ultra short throw projectors, on this score, but the difference isn't as much as you might think. For the 78-inch wide image we use for most testing, I measured the distance between the screen and the front of the S320wi at just 49 inches, which is a lot less than the 110 inches or more for most standard projectors at maximum zoom. I measured the Epson BrightLink 485Wi's distance at just 10-inches, but that's not a truly comparable measurement.

With almost all ultra short-throw projectors, including the 485Wi, the image comes from the back of the projector rather than the front. For the 485Wi, the actual throw distance for a 78-inch wide screen comes out to 21 inches. As a practical matter, if the projectors are mounted above the screen, that doesn't give it much advantage over the S320wi for eliminating shadows when you're standing near the screen. However, it can make a more noticeable difference for projectors on a cart.

Setup and Interactivity

Setting up the S320wi is standard fare. Connection options on the back include an HDMI 1.3 port for a computer or video source, plus the usual assortment of VGA, composite video, and S-Video ports. There's also a  USB A port for reading files from a USB key, a USB B port for connecting to your computer for interactive control and mouse control, a LAN port for both sending images to the projector and controlling it over a network, and support for a Wi-Fi connection.

As with most DLP-based interactive projectors, including, for example, the Editors' Choice Optoma TW610STi the S320wi uses the Texas Instruments interactive technology, which doesn't need calibration between the supplied pen and the projector. In addition the pen doesn't need to touch the screen to interact, so you can turn literally any surface into the equivalent of an interactive whiteboard.

As is typical for projectors using TI's approach to interactivity, I saw a slight lag between moving the pen and the results onscreen at times, but the responsiveness was good enough so I don't consider it a problem.

Brightness and Image Quality

The S320wi is bright enough for the 78-inch wide (98-inch diagonal) image size I used in my tests to easily stand up to the level of ambient light you'll find in most offices and classrooms. Turn on interactive mode, however, and the brightness drops noticeably. The good news is that even with interactive mode, the image was bright enough for a 66-inch wide (83-inch diagonal) image with moderate ambient light.

Very much on the plus side, the S320wi did reasonably well for data image quality on our standard suite of DisplayMate tests. Color balance was good, with most preset modes delivering suitably neutral grays over the entire range from black to white. Colors were a little dark in terms of a hue-saturation-brightness color model, but the colors were generally well saturated. More important for data images, the projector holds details well, with text easily readable at sizes as small as 6.8 points.

Video quality is also good for a DLP data projector. The S320wi handled skin tones well, I didn't see any posterization (shading changing suddenly where it should change gradually) even in scenes that tend to cause the problem, and I saw only minimal noise in large solid areas, like blank walls. I also saw moderate loss of shadow detail (details based on shading in dark areas) in scenes that tend to cause the problem, but many, if not most, data projectors do far worse with shadow detail.

One potential issue for any DLP based projector is rainbow artifacts, with light areas breaking up into little red-green-blue rainbows. I see this rainbow effect relatively easily, but it showed so rarely with data screens on the S320wi that few people, if any, are likely to find it bothersome. As with most DLP projectors, however, the rainbows show more often with video. Anyone who's sensitive to the rainbow effect may well see it often enough with video to consider it annoying.

Other Issues

Two other issues that demand mention are the S320wi's audio system and its 3D support. The audio quality is good enough so I could hear every word of some quietly spoken dialog that's almost impossible to make out with most projectors. Unfortunately, that's balanced by low volume, with a five-watt speaker. For larger rooms, you'll want to use an external sound system.

The 3D support, using DLP-Link glasses, is typical for DLP projectors, which means the S320wi is designed to work with computers that include Quad Buffered, Open GL 3D-compatible graphics cards. It also comes without any DLP-Link glasses, which are currently about $30 each for the cheapest models available. Buying enough glasses for a large audience can be costly enough to make 3D impractical. But at least the feature's available if you want it.

Overall, if you need an XGA interactive projector, the Dell S320wi offers a lot to like, with its short throw and its level of data and video image quality. However it's also a little pricey. Comparable in most ways to the Optoma TW610STi but with a lower resolution, at XGA (1,024-by-768) instead of WXGA (1,280-by-800), it should cost less. Instead, it costs more. That said, if XGA is the resolution you need, the Dell S320wi will be the better fit. And despite its price, it's a fairly reasonable choice.

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