Designed for both gaming and home entertainment, the Optoma UHD55 projector ($1,799) offers 4K resolution (3,840 by 2,160 pixels), impressive color quality, and the short input lag that gamers demand. The competing BenQ TK700STi has a few more features, including fully integrated Android TV. But the UHD55 wins on the core issue of image quality. Although it falls just short of being an Editors' Choice pick, that's enough to earn it the higher rating of the two.

How Short a Lag Measure Do You Need?

The UHD55's input lag, as measured with a Bodnar meter, was 16.9 milliseconds for 60Hz input at both 4K and 1080p resolutions. That translates to a faster 4K response than most projectors can manage, putting it within the range that a serious gamer would consider acceptable. Even better, the lag dropped by roughly half, to 8.6ms, for 1080p/120Hz input. Note that for all three measurements, the UHD55 was essentially tied with the TK700STi. The results are also consistent with both projectors' ratings of 4.2ms for 1080p/240Hz input, of which the most serious gamers may want to take advantage.

As is standard for 4K DLP models, the UHD55 is built around a 1,920-by-1,080-pixel DLP chip that uses TI's fast-switch pixel shifting to generate 3,840 by 2,160 pixels on the screen. Many newer projectors use lasers or LEDs as their light sources, but the UHD55 takes a more traditional approach. It uses a lamp paired with an eight-segment color wheel that offers two sets of red, green, blue, and white panels. The white segments are common in DLP projectors designed for rooms with ambient light, because they boost brightness. They can also hurt color accuracy, but Optoma has done a good job of countering that tendency. The loss of color accuracy shows only in the brightest mode, and even then is less obvious than typical.

At 8.6 pounds and 4.7 by 12.4 by 10.6 inches (HWD), the UHD55 is a little heavier than the TK700STi, but light enough to bring with you for gaming on the go. Physical setup is straightforward. A 1.3x zoom and a small vertical lens shift—5% of the image height up or down from the centered position—add welcome flexibility for where you can place the projector and for avoiding using digital keystone correction.

There are two HDMI ports, but only one supports the short input lag, so you'll want to be sure to connect your gaming source to the correct port. There's also an Ethernet port and built-in Wi-Fi for connecting to the internet to enable the projector's smart features. In addition to voice control using Amazon Alexa or Google Assistant, the UHD55 also offers Optoma's InfoWall feature. InfoWall lets you assemble a set of tiles to show assorted information, including weather reports, your calendar, and news. Both voice control and InfoWall make use of Optoma's online servers. Unfortunately, the servers were undergoing some updates during my testing, so the smart features didn't work as promised. Optoma says the updates should be finished by publication time.

The projector also offers streaming apps from Optoma's Marketplace. I counted a total of 18 apps; however, only 10 of them were for streaming video. The good news is that Netflix and Amazon Prime Video are included. Other popular staples, like Hulu and YouTube, are not. You can always plug a streaming dongle into one of the HDMI ports, of course. A final smart feature is support for IFTTT (If This Then That) applets, which can do things like automatically mute the projector when someone rings your smart doorbell.

The onboard 10-watt chamber speaker offers usable sound quality at high enough volume to fill a large family room. For connecting to an external sound system, there's a 3.5mm analog stereo output and an S/PDIF digital output.

Top-Tier HDR Picture Quality

The UHD55 offers high dynamic range (HDR) color, with support for both HDR10 and HLG HDR. There are 10 predefined color modes plus three ISF modes—Day, Night, and 3D—if you want to pay someone to do a full-scale calibration for your room and screen. Six of the 10 predefined modes are for SDR input, two for HDR10, and two for HLG HDR.

After some preliminary tests, I chose Cinema mode for watching SDR movies and video. Game mode offered better shadow detail, but it brightened up dark scenes more than they should have been. That's good for spotting objects in the shadows quickly in games, but not good for movies, where it can lessen the visual impact. Note that Bright mode (the brightest) was not as green-shifted as many projectors' brightest modes, making it at least tolerable if you need the projector's top brightness on a particularly sunny afternoon in a family room, for example.

For 1080p SDR movies and video, Cinema mode delivered top-tier color accuracy for the price class, and good contrast in both dark and brightly lit scenes, using a 90-inch, 1.0-gain screen. In a dark room, the shadow detail, contrast, and sense of three-dimensionality combined to offer an appropriately dramatic visual impact. The image was also easily bright enough to stand up well in a family room at night with lights on.

For my 4K HDR tests, the UHD55 delivered a notable step up in image quality, which isn't true for all projectors that support HDR. I chose the HDR mode for my tests rather than the WCG_HDR setting. (WCG is short for wide color gamut. There are two equivalent choices for HLG.) I also turned on frame interpolation (FI). The feature smoothes motion, but it also tends to make 1080p filmed material look like live video. With 4K HDR, on the other hand, it can add a greater sense of contrast and three dimensionality—as it did with the UHD55—without the digital video effect. In the viewing tests, the 4K versions of the discs for the same movies I viewed at 1080p SDR delivered more saturated, more accurate color, and the shadow detail was better enough to give objects in dark scenes a far more three-dimensional look.

The UHD55 also supports Full HD 3D using DLP-Link glasses. Compared with most current projectors, the 3D-related motion artifacts were a little more obvious than typical, but I didn't see any crosstalk.

As with most Optoma models, the UHD55 also did a good job of resisting showing rainbow artifacts (red-green-blue flashes). Despite seeing these easily, I encountered almost none when using 1080p input. They showed a little more frequently with 4K input, but still not as often as with most DLP projectors. As always, however, if you're concerned about seeing these artifacts, buy from a dealer who allows easy returns, so you can test it out for yourself.

Based on the Society of Motion Picture and Television Engineers (SMPTE) recommendations, the rating of 3,600 ANSI lumens for the UHD55 would be bright enough for a 275-inch diagonal, 1.0 gain, 16:9 screen in a dark room. In my tests using the lower-brightness Cinema mode, it was easily bright enough to light up my 90-inch, 1.0-gain screen well enough to be watchable even in moderate ambient light. It was also quite watchable, if a little washed out, on an 80-inch, 1.0 gain screen in a family room with lots of windows on a bright afternoon.

Good for Gaming, Just as Good for Movies

If you'd rather shop in a lower price range, you might want to consider 1080p projectors, including the Optoma GT1080HDR and the BenQ X1300i. But if you're looking for a 4K projector for gaming, home entertainment, or both, the Optoma UHD55 is a strong contender, along with the BenQ TK700STi.

For serious gamers, the BenQ projector offers multiple game modes that optimize video and sound settings quickly and easily for different types of games. For some gamers, that could be enough to give it the edge. For watching video and movies, on the other hand, both projectors delivered top-tier picture quality for 1080p SDR, but the UHD55 did a better job for 4K HDR. The UHD55 also shows fewer rainbow artifacts, which is a big advantage for those who find them bothersome. If you want 4K resolution for gaming and home entertainment, both are worth a look, but the UHD55 belongs on your must-see list.