BenQ TH685

The BenQ TH685 ($799) is one of a growing number of 1080p projectors that can accept 4K (3820-by-2160) HDR input, downconvert the image to show at 1080p resolution, keep the HDR, and deliver a bright, highly watchable picture. Like other projectors in this category, including the Optoma GT1080HDR  and Optoma HD39HDR, it supports HDR10, found on UHD Blu-ray discs and other recorded material. Unlike many, it also supports HLG, the emerging standard for broadcast TV. For both HDR and SDR (standard dynamic range) content, it delivers good color accuracy and contrast, especially given its relatively low price. And at a rated 3,500 lumens, it’s easily bright enough to deliver a satisfyingly big picture in ambient light. 


Built for Both Brightness and Color

The TH685 pairs a single 1920-by-1200 DLP chip with a six-segment, RGBWYC (red-green-blue-white-yellow-cyan) color wheel, but uses only 1920-by-1080 pixels on the chip as its native resolution. The extra pixels let you shift the picture up or down from the center position by 5 percent of the image height, as a convenient way to position the image for your screen.

The color wheel’s white segment lets it deliver a brighter image than you would get from an otherwise identical projector without one. However, it also affects color accuracy, which is why color wheels in projectors meant for traditional home theater in a dark room—such as the BenQ HT2150ST—don’t include white panels. The yellow and cyan segments help correct for that, with the yellow segment helping deliver brighter, more vibrant yellows than many DLP projectors can manage. 

BenQ TH685 top

The TH685 is small, light, and easy to carry.

Setup and Viewing

At 6.2 pounds and 4 by 12 by 9 inches (HWD), the TH685 is easy to handle for setup. The digital image shift and 1.3x zoom lens also add flexibility for positioning. And if you need to tilt the projector up or down even after adjusting the shift, you can square off the image with the +/- 30 degree vertical keystone control.

I set up the projector for a 90-inch image at 7 feet, 3 inches from the screen. One small annoyance is that it’s harder than it should be to get the image well focused. Moving the focus ring just a little changes the focus a lot, making it hard to adjust without overshooting the right setting.

Image inputs include two HDMI 2.0b ports, which both support HDCP 2.2 (the copy protection version on 4K Blu-ray discs). There’s also a USB port, meant strictly for supplying power to HDMI dongles. 

BenQ TH685 back ports

The back panel hosts various ports for input and power.

Even with default settings, image quality is good for the price, and easily rates as more than acceptable by most standards. Once you get the focus right, image detail is appropriate for the 1080p resolution, and colors for movies and video are well within the range for realistic color in all but one of the predefined color modes. As with most projectors, Bright mode sacrifices color accuracy for visibility in a setting with lots of ambient light, such as in a family room with lots of sunny windows. But most people will find the slight green shift tolerable if they only need to use Bright mode occasionally.

For SDR content, Cinema mode has the best color accuracy and is the one I chose for most of my testing. But Living Room, Standard, and Game modes were not far behind. Sports mode isn’t as good, but its color was rarely outside of a realistic range in my tests, and only slightly off when it was. The four modes with better color accuracy were all closely matched on contrast, black levels, and sense of three-dimensionality in dark scenes. Living Room and Game modes both brightened up shadow detail just a little. This can steal visual impact from dark scenes in movies, but can help gamers spot what’s happening in dark areas more quickly. All these modes did a good job of showing the subtle gradations that make close-ups of rounded objects, such as faces, look three-dimensional. 

BenQ TH685 front and top

For a small and relatively inexpensive 1080p projector, the TH685 produces impressive color accuracy.

For HDR testing, I used 4K discs only, since HLG content is still more of a promise than a reality at this writing. But, according to BenQ, both modes work essentially the same way. In my tests, the TH685 switched to its single HDR10 mode and automatically downconverted the 4K image to the projector’s native 1080p. As with most HDR projectors, the TH685 offers what’s usually called an HDR brightness setting for manual adjustment. The best setting will vary with the ambient light level as well as from movie to movie.

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In my tests with 4K HDR movies, brightly lit scenes had nicely saturated color and good contrast. Dark scenes were similar enough to the SDR versions of the same movies that—with no way to do a side-by-side comparison—differences were hard to pinpoint. My impression is that they offered the same shadow detail as in SDR, but with darker gray levels to yield a more dramatic image and greater sense of dimensionality. 

Like most of its direct competitors, the TH685 has several settings for fine-tuning the image range: general brightness, contrast, and gamma adjustments, plus a color management system for adjusting hue, saturation, and gain separately for each primary and secondary color. 

The rated 3,500 lumens is bright enough, according to the Society of Motion Picture and Television Engineers (SMPTE) recommendations, to light up a 270-inch diagonal screen in a dark room or a 150-inch screen in moderate ambient light, assuming a 1.0-gain, 16:9 white screen. As with most projectors, however, the modes you’re most likely to use don’t project at full brightness. For my formal tests in a dark room, Cinema mode was bright enough to fill a 90-inch-diagonal white screen. In informal tests in a family room with lots of windows, it was still bright enough to light up an 80-inch 1.0-gain white screen for nighttime viewing with lights on or for daytime viewing on a rainy day. 

As is typical in this price range, the TH685 offers a single 3D picture mode and works with DLP-link glasses only. I saw no crosstalk or ghosting in my tests, and only minor 3D-related motion artifacts. 

BenQ TH685

The TH685 gets mixed reviews for rainbow artifacts. I saw these red-green-blue flashes often enough to notice, but they were fleeting, so if you’re not sensitive to them, you may not see them at all. As with any single-chip projector, if you see these artifacts easily—or don’t know whether you do—buy the projector from a source that allows returns without a restocking fee, in case the artifacts do end up bothering you.


Light and Fast With Good Sound

Gamers will appreciate the TH685’s fast lag time. With Fast mode on—the default setting for Game picture mode—my Bodnar meter measured the lag for 1080p, 60Hz input at 16.4 ms. BenQ doesn’t include a carrying case, but the projector is still quite portable; gamers who need a projector they can easily carry from room to room or to a friend’s house will appreciate the small size and light weight.

As a pleasant surprise, it also delivers far more robust audio than you would expect from its onboard 5-watt mono speaker, thanks to the chamber design. Audio quality is good for such a small projector, and the volume is high enough to fill a large family room. For stereo or truly high quality, however, plan on using an external sound system. 


A Top Contender

If you’re on a tight budget, you might want to consider less expensive 1080p projectors. The ViewSonic PX701HD ($590) and BenQ’s own TH585 ($599), for example, are also designed for gaming and for watching movies and video in ambient light. But they leave out support for HDR and 4K input.

Two other choices that are more directly competitive and worth a close look are the Optoma HD39HDR and Optoma GT1080HDR. Both share the TH685’s ability to accept 4K HDR input and downconvert it to 1080p HDR, and both offer somewhat higher brightness ratings. However, the TH685 is the only one of the three that also supports HLG, which gives it an important edge.

Our tests found little to complain about, and perks such as the good onboard audio sweeten the deal. If you want HDR and HLG support in a sub-$1,000 1080p projector, the BenQ TH685 is the one to beat. 

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