Introduction

Optoma is a little late to the game with its first ultra short throw interactive projectors, but its first generation TW675UTi-3D is fully competitive with other companies' second and third generation models. In addition to interactivity and the ultra short throw, it's 3D-ready and, according to Optoma, will work just as well projecting downwards to create an interactive table top as in a horizontal position for projecting on a screen.

Built around a 1280x800 DLP chip, the TW675UTi-3D offers a 3200 lumen rating, the ability to turn on both interactive and 3D modes at the same time, and a size and weight that's appropriate for either permanent installation or a cart. It also offers a longer than usual, three-year warranty, which helps make it a more than reasonable choice at $1,799, with an education discount available through Optoma.

Advantages

It's Interactive. As with any interactive projector, the interactivity is the main reason for considering a model that costs about 30 percent more than comparable choices without the feature. The TW675UTi-3D uses TI's interactive technology, which works by superimposing a grid on the image, with the grid serving the same purpose as map coordinates. The grid is invisible to the human eye but visible to the interactive pen, which lets the pen tell the projector what it's pointing at. Optoma includes one pen with the projector.

As is standard, you can use the pen as both a mouse and a drawing tool. It should work with any annotation software, but in case you don't already have a program, Optoma provides WizTeach, which includes some special features for the classroom, like built-in maps, but will serve just as well for business use.

Ultra short throw. At least as important as interactivity is the ultra short throw, which lets you project a large image and still stand close to the screen without worrying about shadows. Optoma's stated range for image size runs from 77" to 100" diagonally at a distance of 19.3" to 25.8" from the screen to the mirror at the back of the projector. That translates to roughly 4" to 10" from the front of the projector. For our tests at the native 1280x800 resolution, we measured a 92" diagonal image at 10" inches from the front.

No calibration. One of the strengths of TI's interactive technology is that because the grid always falls on the same place relative to the image, there's no need for calibration. This is particularly welcome if the projector is on a cart that you move into place each time you use it. Simply turn everything on, and the interactive feature is ready to use.

Can use any surface and can move away from the screen. Because the pen only has to see the screen, rather than touch it, you can use literally any surface. You can also stand to one side of the screen or step away and interact from a distance. Keep in mind, however, that it's hard to control what you're pointing at from more than a few feet.

Reasonably fast reaction time. One minor issue with early TI-based interactive projectors was a slight lag between moving the pen and seeing a result on screen, which took some practice to get used to. The TW675UTi-3D shows just a hint of that lag, but little enough so that using it feels natural immediately.

Bright enough to leave the lights on. Optoma rates the TW675UTi-3D at 3200 lumens, and we measured it as just a touch brighter, at 3338 lumens. That's more than bright enough to stand up to typical conference room or classroom lighting with the 92" diagonal image we used. Turning on interactive mode has only a small effect, basically dropping the projector to its rated brightness, at 3187 lumens. The lamp's Standard mode, which is the equivalent to an Eco mode, drops the brightness by about 15%, to 2840 lumens, which is a fair trade for increasing rated lamp life by 20%, from 2500 hours to 3000.

Various other presets came in at a range of 958 to 2168 lumens, which makes it easy to adjust the projector for lower levels of ambient light. Note too that the TW675UTi-3D is unusual, if not unique, in letting you turn on both interactive and 3D modes at the same time. However the brightness drops to just 565 lumens.

Good data image quality. The TW675UTi-3D's image quality is more than good enough for business or classroom use, despite some minor flaws. In the brightest mode, colors were a little dark (in terms of a hue-saturation-brightness model), but well saturated and suitably eye catching. In the default Presentation mode, colors were more vibrant. However, yellow was verging on a mustard color in both modes. Both black on white and white on black text was crisp and readable even at the smallest sizes we test with, except at the extreme upper right and left corners of the image. Both corners were in slightly soft focus compared to the rest of the screen, by just enough to make fine detail a little hard to make out.

Better than par video quality. Although not in the same league as a home theater projector, the TW675UTi-3D does better than most data projectors with video. I saw no motion artifacts or posterization (colors changing suddenly where they should change gradually), even in scenes that tend to cause these problems, and it handled skin tones and shadow detail surprisingly well. More than most data projectors, it's suitable for relatively long video sessions as well as data.

Surprisingly few rainbow artifacts. Single chip DLP projectors can potentially show rainbow artifacts, with light areas breaking up into little red-green-blue rainbows when you shift your gaze or an object moves on screen. The TW675UTi-3D does a far better than average job of avoiding this problem. The artifacts show so rarely on data screens that even those who are sensitive to them should rarely see them. They show more often on video screens, but still rarely enough so that even among those who see the rainbows easily, few, if any, should find them annoying.

Good connectivity. The projector's side panel offers a full set of connectors, starting with an HDMI port for a computer or video source, two VGA ports for computers or component video, a VGA passthrough port, and both S-video and composite video inputs. For audio, in addition to the HDMI input, there's a single miniplug shared by the two VGA connectors and a set of stereo RCA phono plugs shared by the composite and S-video ports. There is also a miniplug for a microphone and another for stereo audio output.

The three USB ports include one mini-USB port for connecting to a computer for interactivity, a second one for a data connection to a computer, and a USB A port that lets you plug in a $29 optional WiFi dongle for data or plug in a USB memory key to read JPG and BMP files directly. Finally, there's a 12v trigger to let you automatically lower and raise a screen when you turn the projector on and off, and an RS-232 port for controlling the projector through a computer or third party controller.

Works for interactive table top. Setting up a projector to project down for an interactive table top can create problems. If the cooling system isn't designed for it, the projector may overheat and shorten lamp life. According to Optoma, however, you can use the TW675UTi-3D for an interactive table top with no change in settings and without affecting lamp life.

Better than typical warranty. The TW675UTi-3D's warranty is longer than most, at three-years for the projector and one-year for the lamp.

Limitations

Borderline acceptable brightness uniformity. Maintaining uniform brightness over the entire screen is a challenge for ultra-short throw projectors, so it's not surprising that the TW675UTi-3D's brightness uniformity is a relatively poor 56%. The brightness difference showed as cool spots at the upper left- and right- hand corners of the screen, but was obvious only on solid light colored screens. On screens broken up by text and graphics, we could still see the difference, but might not have noticed it if we didn't already know to look for it. Few people should find it objectionable.

Auto-Iris lag. The TW675UTi-3D doesn't have a physical auto iris to make dark images darker and bright images brighter, but it uses an electronic equivalent. Unfortunately, it shares one of the common flaws of the real thing, with a lag between an image appearing on screen and the brightness changing. Some people find this annoying. The good news is that you can turn the feature off easily. If you ever reset the projector to its default settings, however, you'll have to remember to turn it off again.

Low volume audio. The two 5-watt stereo speakers deliver reasonably good quality audio, but only enough volume for a small conference room. If you need a higher volume, you'll need to connect to an external sound system.

Limited 3D. The TW675UTi-3D earns points both for being 3D ready and for being able to use 3D along with interactive mode. As with most inexpensive 3D-ready projectors today, however, the 3D won't work with Blu-ray players or broadcast 3D signals unless you have an external converter. Potentially even more of an issue is that you'll need enough pairs of DLP-Link glasses (currently $70 or more each) for your audience.

Conclusion

Whether you want to set up the equivalent of an interactive whiteboard or an interactive table top, the TW675UTi-3D's strengths, particularly its brightness, ultra short throw, and data and video image quality, far outweigh its few weaknesses. Few ultra short throw, interactive projectors offer 3D, much less 3D that works along with interactivity, and few offer video quality suitable for anything more than short clips. Fewer still offer all of these features in the same projector, which means that the TW675UTi-3D's combination of features will be hard to find anywhere else.

For more detailed specifications and connections, check out our Optoma TW675UTi-3D projector page.

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