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Sometimes, a specialized tool is required. Maybe that Swiss Army knife has gotten you out of a few jams, but it lacks useful things like a hammer or a belt sander. Most home theater projectors are generalist tools as well, equally adept at a variety of content. BenQ TH685 is not a Swiss Army knife. It's a hammer. With low input lag and a massive, bright image, this is the kind of display gamers can use to effectively pwn the noobs, on a 100-plus-inch screen, while even leaving some lights on.
The downside is that its contrast ratio and overall image quality come up a little short, and when used in its most accurate mode for color, its brightness is basically the same as the competition. The TH685's short-ish throw distance lets you get a huge image from your coffee table, but combined with lack of lens shift it limits placement compared to other projectors.
The BenQ TH685 was designed to fill its niche as a gaming projector, but outside that role it falters a bit. The cheaper BenQ HT2050A has a superior picture with punchier contrast and comparable brightness in accurate picture settings, making it a better choice for all kinds of general viewing. But if your primary use is playing games, and you want to fill a massive wall doing it, the TH685 is an excellent tool for the job.
The TH685, like the Optoma HD28HDR, can accept a 4K resolution signal, but it's a 1080p projector. Ultra HD images will be scaled down to 1080p. This is likely done because 4K and HDR often go hand in hand, even though that's not technically necessary. Both HDMI inputs can accept 4K.
If you're still a fan of 3D, the TH658 can do that too, though the glasses aren't included.
BenQ claims 3,500 lumens of brightness. In its most accurate setting, with color close to what you want in a home theater environment, I measured just over 1,600. In the Bright picture mode the image is noticeably and unpleasantly green but measures an impressive 2,782 lumens. I don't recommend watching in this mode for any length of time, but if the room has ambient light, gaming with the lights on during a party, say, having the ability to be this bright can come in handy.
Though I should mention, no projector can compete with ambient light. All projectors will look better with some light control.
There's no manual lens shift, a feature found on the TH685's cheaper brother, the HT2050A. The TH685's digital lens shift isn't as good, but it is something. It moves the image center up or down on the DLP chip, cropping whatever part of the image doesn't fit. If you're watching a widescreen movie, for example, you can position the image up or down the screen since the back bars can be cropped out without losing any pertinent info.
Throw distance is on the shorter side. Despite having a 1.3x zoom, it requires closer placement to the screen than some of its direct competition. If you don't want to mount it on the ceiling, it's not going to work behind your head unless your sofa is fairly close to the screen, or the screen itself is quite massive. Conversely, you can put the projector closer to the screen, so coffee table placement would still allow a big image. It is not, however, a true short-throw projector.
For perspective, I have a 102-inch screen, and most sub-$1,000 projectors can fill that sitting on a stand behind my sofa, roughly 12 feet from the screen. The TH685 joins us on the couch like an untrained puppy. Also like a puppy its breath is hot and its bark is loud -- when you sit too close to any projector you can feel the heat as well as hear more fan noise.
Lamp life is a fairly average 4,000 hours in the Normal mode. This jumps up to 10,000 hours in the Eco mode, though you lose about 35% of the light output. There are two other lamp modes that sound like they do the same thing, but work slightly different. SmartEco mode decreases lamp power in darker scenes "while optimizing display quality," as BenQ describes. This results in a claimed lamp life of 8,000 hours. LampSave, on the other hand, decreases lamp power in darker scenes "while offering a longer lamp life." It does this primarily by limiting maximum light output to what you'd get in the Eco mode. It balloons lamp life out to 15,000 hours. Since the lamp itself is around $160 as of this writing, and even in the Normal mode will last upwards of three years, you probably don't need to sweat this too much.
Both the HDMI inputs are HDMI 2.0 and have HDCP 2.2, so they can accept 4K HDR signals from any current source. The USB has 1.5 amps of power available, meaning you can drive a streaming stick like the Roku or Amazon Fire.
Interestingly, there's a legacy analog PC input and output, though I can't imagine either will be used by many people. The same goes for the RS-232 port, something required by some high-end home theater control systems.
There's a 5W internal speaker that is about as good as you'd expect. A 3.5mm audio output is available to connect an external speaker. The remote isn't backlit, but it's small and simple and has dedicated and color coded on and off buttons.
I connected these three projectors via a Monoprice 1x4 distribution amplifier, and viewed them on a 102-inch 1.0-gain screen. The TH685 was like a combo of the Optoma and the HT2050A, sharing the above-average color accuracy of the HT2050A with the middling contrast ratio of the Optoma.
The BenQ TH685's color accuracy is welcome, and rare with projectors in this price range. Most sacrifice color for light output. The TH685 has both, which is great. Greens, like grass, plants or a TIE fighter's lasers, are all especially realistic. What, are you saying TIE fighters aren't real? How dare you. Both the BenQs outdid the Optoma here, with the 28HDR just looking a bit less vibrant.
Contrast ratio, as has been the case with all the projectors I reviewed this year, ended up being a no-contest win for the HT2050A. It's just noticeably better in this incredibly important test. The TH658 and 28HDR are basically tied, in terms of contrast. Their slight differences aren't visible side by side. The HT2050A has nearly 3x the contrast ratio, and it's obvious. Shadows are darker, the image has more apparent depth, it just has more punch. The other two look flat in comparison. I wouldn't call them "washed out" like early LCD TVs or projectors, but the 2050A just draws the eye to its more pleasing image.
The HT2050A isn't HDR, so for my final test I focused on the Optoma and the TH685. The Battle of Crait in the Last Jedi was a good test of the HDR, with bright white salt/sand, explosions, and the vivid reds of the underlying minerals. The TH685 had more natural colors, and a more natural color temperature, the Optoma having a green tint. The sky, however, was a richer blue on the 28HDR. In the end, the TH685's extra brightness and greater color accuracy won out, but it was hard to pick a favorite here. Neither looked hugely different with HDR compared to SDR, which is to be expected with projectors.
There is one last oddity. There are slight chromatic aberrations, caused by, I think, inexpensive lens elements. It's not really obvious from a normal viewing distance, but with fine lines, like white on a dark background, the issue becomes quite obvious. Closing credits in a movie, for instance. One edge will have a green tinge, the other magenta. It looks like a panel misalignment, except this is a single-chip projector. This slight tinted halo isn't something that you might notice when watching a movie, but if you've got a menu up, you might notice it.
There are two things that stand out about the TH685: the brightness and the color. It's great to have both those things available in the same projector. Adding in low input lag, and it's easy to see a place for this projector in some people's homes.
That said, more people would probably have better luck with the HT2050A. Putting out the correct color temperature, these two projectors have basically the same light output, with the HT2050A having a significantly higher contrast ratio. The HT2050A also has a game mode that matches the HT685's input lag, and it has lens shift.
So when it comes down to it, the TH685 is really just for people who need the extreme light output potential, either for a ginormous screen or if they want to leave some lights on in a room. If that's not you, the more well-rounded HT2050A is a better option.
|Black luminance (0%)||0.233||Poor|
|Peak white luminance (100%)||182.2||Good|
|Avg. grayscale error (10-100%)||4||Average|
|Dark gray error (20%)||6||Average|
|Bright gray error (70%)||3.427||Average|
|Avg. color error||11.056||Poor|
|Avg. saturations error||5.04||Poor|
|Avg. color checker error||4.8||Average|
|Input lag (Game mode)||16.4||Good|
For the most accurate picture, I used the Cinema mode, along with the Normal color temperature mode. This resulted in a fairly consistent and fairly accurate color temperature across the brightness range, though it was a bit warmer than D65 with an excess of red. With these settings, the TH685 was capable of 182 nits on a 102-inch, 1.0-gain screen, which calculates out to around 1,641 lumens.
Switch to the Bright mode and things change quite a bit. Color temperature accuracy goes out the window, everything looks quite green, but there's a nearly 70% increase in light output, approximately 309 nits, or 2,782 lumens. In a dark room this is incredibly bright. So bright, I doubt most people would use it in this mode to watch a movie. Movie theaters, for comparison, are a faction of this.
Back in the Cinema mode, colors are surprisingly accurate. Red is a little orange, magenta a little red, and green a little undersaturated, but overall quite good for a projector in this price range. You can adjust these some in the picture menu, but not perfectly. Color temperature adjusts far better, though it's pretty close out of the box.
Contrast ratio is fairly average for this category, measuring an average of 853:1 across multiple lamp modes. For comparison, the BenQ 2050A, which is also a DLP projector, averages over 2,000:1. This improves a bit in the Bright mode, thanks to the far greater light output. SmartEco, which varies lamp output depending on video content, has a dynamic contrast ratio of 2,844:1. This mode keeps the light output of the Normal lamp mode. The LampSave mode does the same, but uses the max light output of the Eco lamp mode. This mode has a dynamic contrast ratio of 2,208:1.
Picture Mode: Cinema