BenQ TH671ST 1080P DLP Projector
Projector Central Highly Recommended Award

Highly Recommended Award

Our Highly Recommended designation is earned by products offering extraordinary value or performance in their price class.

  • Performance
  • 4.5
  • Features
  • Ease of Use
  • Value

Designed with gamers in mind, the $699 BenQ TH671ST projector combines a short throw, 1080p resolution, a 3,000-ANSI lumen rating, portability, and—most important to serious gamers—a quick 16.4 ms input lag. It also delivers good color accuracy and suitable contrast for film and video, a combination that puts it in the same league for watching movies or TV as similarly priced home theater projectors. It can even handle presentations nicely. All this makes it a prime candidate for both gamers and anyone else who wants a lightweight projector for home or office, including one they can set up in the backyard for a movie night.

Among the TH671ST's most noteworthy features is its 1.2x zoom, an unusual extra for a short throw. Any short throw lens lets you set up the projector close to the screen for a big image in a small room—for example, small apartments or dorm rooms. But a zoom lens adds convenience and offers greater flexibility of placement, letting you adjust the zoom, rather than move the projector, to match the image to the screen size. This is particularly welcome for portable use, where moving from one location to another means having to set up the projector each time. Portability is also enhanced by surprisingly robust audio for such a small projector.

Brightness is another key feature. We measured the TH671ST at a little over 2,600 ANSI lumens, which is enough to light up a 130-inch 1.0-gain screen in moderately bright ambient light. Even its video optimized setting, at a measured 1,887 lumens, is bright enough at the same light level for a 110-inch 1.0-gain screen or a 120-inch 1.2 gain screen.

BenQ TH671ST

BenQ TH671ST Features / Advantages

  • Rated at 3,000 ANSI lumens, measured at 2,638 ANSI lumens
  • Six-segment RGBYCM color wheel delivers good color accuracy with saturated, bright color
  • 16.4 ms input lag with Fast Mode On
  • Full 1080p 3D; compatible with DLP Link glasses
  • Contrast ratio rated at 10,000:1 (full on/full off)
  • Two HDMI ports, one with MHL
  • USB A port for powering HDMI streaming stick
  • Short throw; 100-inch, 16:9 image from 5 feet away
  • 1.2x zoom
  • Small size and sub 6-pound weight (5.95 pounds) for portability and easy handling for setup
  • 4,000-hour lamp life at full power, 10,000 hours in Economic and SmartEco modes, 15,000 hours in LampSave mode; replacement lamp costs $119
  • 5-watt speaker delivers surprisingly robust audio for such a small projector, with enough volume to fill a large family room; five sound mode presets plus User mode.
  • Manual vertical keystone: +/-40 degrees
  • Three-year warranty; 1 year or 2,000 hours on lamp
  • Rated at 92% Rec.709 coverage
  • LumiExpert feature senses ambient light level and adjusts gamma automatically

BenQ TH671ST Limitations

  • Cannot read files from USB memory; USB A port is strictly for powering HDMI dongle

BenQ TH671ST Performance

Brightness. The BenQ TH671ST test unit came in at 2,638 ANSI lumens in our tests, a solid 86% of its 3,000 ANSI lumen rating. With the 1.2x zoom lens at its widest angle setting, our measurements for Normal and Economic power modes are as follows:

BenQ 671ST ANSI Lumens

MODE Normal Economic
Bright 2638 1696
Vivid TV 1949 1253
Cinema 959 617
Sport 1887 1213
Game 1960 1260

Low Lamp Mode. Compared with the full power mode, Economic mode reduces brightness by about 36%. Two other settings, SmartEco and LampSave, are dynamic power modes that are intended to lenghthen lamp life by adjusting the power level based on scene content. With a standard 100% white image, we measured SmartEco at the same brightness as Normal power mode. LampSave peaked at 1,767 ANSI lumens in Bright mode, just a touch brighter than Economic mode. BenQ says there is no noticeable effect on the image with these modes, nor did we observe any.

Zoom Lens Light Loss. The 1.2x zoom isn't large enough to curtail brightness significantly at the telephoto end of the lens. You can safely ignore the potential light loss when choosing how far to put the projector from the screen.

Brightness Uniformity. The test unit's brightness uniformity is 63%. Somewhat surprisingly—because short throw projectors tend to have problems maintaining uniform brightness—this is actually a better than typical result for standard throw home theater projectors in this price range.

As with virtually all inexpensive home theater projectors we've tested, the brightness variation is easy to see with a 100% white or light colored image. With the projector sitting on a table, brightness is highest at the bottom center of the image, and gradually falls going up and to either side, making the upper left and right corners the dimmest. Those who are particularly sensitive to brightness variations may find this unacceptable. However the difference is hard to see with any image that breaks up the field of view.


Video Optimized Lumens. Both the Cinema and Sport modes are good starting points for optimizing settings for video. Both deliver color that's well within a realistic looking range and close enough to accurate so you wouldn't know that any color is off without a reference image to compare to. However, Sport mode delivers a higher ANSI lumen measurement and brighter shades of yellow, which prove to be more accurate when comparing with a reference image.

With default settings, Sport mode has a slight yellow-green shift, but it is easy to tweak for suitably neutral color, and without affecting either ANSI brightness or the brighter shades of yellow. BenQ's Color Management settings let you adjust hue, saturation, and gain individually for all six primary (red, green, blue) and secondary (cyan, yellow magenta) colors.

At 1,887 lumens for the optimized video settings, the TH671ST can light up a 110-inch 1.0-gain 16:9 screen or a 120-inch 1.2-gain screen in moderately bright ambient light. Even in Economic mode, at a touch over 1,200 lumens, the projector is bright enough for a 100-inch 1.2-gain screen in moderately bright ambient light or a 110-inch screen in typical nighttime lighting in a family room.

Color Preset Mode Performance. Most of the TH671ST's color modes are usable straight out of the box, even for film or video, with varying degrees of color accuracy. As with the brightest mode for most projectors, the TH671ST's Bright mode shows a slight green shift. However it is less than with most projectors, particularly those in this price range.

The bigger problem with Bright mode is the loss of gradations to the point of showing a hint of posterization in demanding images. Despite that, Bright mode with defaults is our choice for the presentation-optimized setting, even for presentations that include photorealistic images. Most people will also consider it acceptable for occasional use in, say, a family room in daytime when they absolutely need the extra brightness.

Vivid TV mode has a slight blue shift from neutral, which is much less of an issue than a green shift for most people, and in any case is slight enough that you're not likely to notice it without a reference image to compare it with.

Cinema and Sport modes, as already mentioned, both deliver good color accuracy by default, and the best accuracy of any of the modes. Game mode straight out of the box is a little cooler than the Cinema and Sport modes, with a whiter white and skin tones that look a little too porcelain in some images.

Contrast. As is typical for BenQ projectors, the TH671ST test unit's defaults for contrast and brightness were set properly in all modes to maximize shadow detail and highlight separation in a dark room. The most we would change is a single step in one direction or the other for some modes, but whether it actually needs a settings change is a judgment call. Contrast, shadow detail, black level, and three dimensionality are all excellent for the price.

Those seeking to to improve contrast will want to experiment with the LumiExpert feature. LumiExpert detects the ambient light level and adjusts gamma appropriately for the lighting. You can also turn it off and adjust its setting to make the overall picture a little darker or a little brighter at any given ambient light level. We found that choosing the right setting can significantly increase contrast and the sense of three dimensionality in dark scenes.

Note that we saw an occasional skipped frame when watching movies at 24 frames per second (fps)—though not at 60 fps. Skipped frames are usually visible as a random, judder-like jump (only bigger) in the middle of a camera pan, or in the movement of an on-screen object when the camera is fixed. It seemed to happen more frequently with LumiExpert on, however, these skips were rare and not reliably repeatable. BenQ has been looking into the issue to determine if it's isolated to our set-up or something that might require a firmware correction.

3D Performance. The TH671ST delivers usable 3D with support for DLP Link glasses only, but its 3D performance doesn't stand out from the crowd. I saw no crosstalk in my tests, and 3D-related motion artifacts are less obvious than with earlier generation 3D projectors. However they are more obvious than with most current models. The single 3D color mode is roughly as bright as Cinema mode—the least bright 2D mode—before factoring in the loss of brightness from using 3D glasses.

Rainbow artifacts. The TH671ST gets mixed results for rainbow artifacts. I saw them more often than with most current models, but they were surprisingly fleeting. If you're not sensitive to rainbows, you may not see them at all. But if you are particularly bothered or don't know if you are, consider purchasing from a dealer that allows easy returns so you can test this for yourself.

Onboard audio. The TH671ST's audio is a pleasant surprise for such a small projector. The 5-watt mono speaker delivers high enough volume to fill a large family room, and the audio quality is surprisingly good, with five sound mode presets to choose from—Standard, Cinema, Music, Game, and Sport—plus a User mode. BenQ says it uses digital audio enhancement algorithms to enhance bass and treble. You may still want an external sound system—to enjoy stereo sound, for example—but for portable use or a backyard movie night, the built-in audio should be all you need.

Fan noise. BenQ rates the TH671ST at 33 dB in full power mode and 29 dB in Economic mode. In either one, you can hear it in quiet moments from anywhere in a typical-size family room, but it is the sort of steady whoosh that tends to fade into the background in rooms with other ambient noise, particularly in Economic mode.

BenQ recommends using High Altitude mode at 4,921 feet and above. With High Altitude on, most people will want to stay with Eco mode, which is quieter than full power mode with High Altitude off, but with a higher pitch that makes it a little more intrusive. With full power, High Altitude mode both increases volume and raises the pitch.

Input lag. With Fast Mode on, the TH671ST's input lag is 16.4 ms in Bright and Sport modes and 16.6 ms in Vivid TV and Game modes. Both are fast enough for serious gamers. Input lag for Cinema mode is only slightly longer, at 18.8 ms. With Fast Mode off, the lag jumps to about 50 ms for all modes but Cinema, which is 52.2 ms. The default setting for Fast Mode is On for Game mode, and Off for all other modes.

BenQ TH671ST Connection Panel Inputs

BenQ TH671ST Connections

  • (2) HDMI v1.4a, 1 with MHL
  • (1) VGA in
  • (1) VGA monitor out
  • (1) 3.5 mm audio in
  • (1) 3.5 mm audio out
  • (1) USB A (for power only)
  • (1) RS-232
  • (1) USB mini B (for firmware upgrades only)

Setting Up the BenQ TH671ST

Throw Distance. Unlike most short throw projectors, the TH671ST offers a zoom lens, which adds flexibility for positioning the projector to help make setup easy. Simply place the projector at approximately the right distance from the screen, and then fit the image to the screen by adjusting the 1.2x zoom, rather than moving the projector. The range for a 110-inch 16:9 image is roughly 5.5 to 6.7 feet. The BenQ TH671ST Projection Calculator will let you find the throw distance range for the image size you want.

Lens offset. The lens offset for the TH671ST is designed for placement on a low table, with the bottom edge of the image falling somewhere between the lens centerline and up to 5% of the image height above it. For example, with a 100-inch high image the bottom edge would be anywhere between even with the lens centerline and 5 inches above it. The bottom edge of the image on our test unit was about 4% of the image height above the centerline, which is within typical sample-to-sample variation.

Our Take on the BenQ TH671ST

BenQ TH671ST

At $699, the BenQ TH671ST is an impressive gaming projector and a solid value. It delivers nicely saturated color, suitably good contrast and shadow detail for dark scenes in games, and an input lag of just 16.4 ms. Beyond that, most of its strengths for gaming, combined with its not quite 6-pound weight, also make it a highly capable portable projector for home, office or both, with the short throw making it of special interest to anyone who is looking to project a big image in a small room.

The ease of setup, thanks to the short throw lens and 1.2x zoom, along with an excellent sound system for such a small projector, are just as helpful for a portable home theater or business projector as for gaming. Even better, the TH671ST is very much in the same league as similarly priced home theater projectors for color accuracy, black level, and shadow detail, while color for animations or business graphics is vibrant and suitably eye catching.

With video optimized settings, the TH671ST can light up a 120-inch 1.2-gain screen in moderately bright ambient light using full power, or a 100-inch 1.2-gain screen in Economic mode. And the LumiExpert feature can adjust gamma automatically for the current ambient light level, with a dedicated menu button on the remote so you can easily tweak its effect to taste.

The BenQ TH671ST's combination of brightness, color accuracy, contrast, ease of setup, short throw with zoom, quick input lag, and light weight makes it easy to recommend both as a gaming projector and for broader use. It is particularly well suited if you need a portable projector, whether for carrying to the office occasionally, setting it up for a backyard movie might, or moving it room to room for movies or game playing. For any of these applications, the BenQ TH671ST should definitively be on your short list.

For more detailed specifications and connections, check out our BenQ TH671ST projector page.

To buy this projector, use Where to Buy online, or get a price quote by email direct from Projector Central authorized dealers using our E-Z Quote tool.

Comments (24) Post a Comment
Mike Posted Jan 22, 2019 7:09 PM PST
I can confirm I also get the judder with the LumiExpert on. The judder/jump really ruins an otherwise great feature. I have to turn LE off or it is too distracting watching sports or anything with a scrolling ticker on the screen.

I would love to see a firmware update to solve this issue... Come on BenQ!

I'm really happy with TH671ST otherwise. I use it for TV and movies is a fairly bright space and it has enough punch to deliver a quality image. I wish the blacks were blacker when watching a movie at night, but room treatments have help quite a bit.
Rob Sabin, Editor Posted Jan 23, 2019 8:26 PM PST
Michael, thanks for the feedback. I've forwarded your comment to BenQ to assist them in their investigation.

Jerome Posted Jan 25, 2019 3:12 AM PST
Hello, which will advise you between the TH671st and the Viewsonic PX706HD?
Rob Sabin, Editor Posted Jan 25, 2019 8:04 AM PST
Jerome, published specs are very similar on these. I'd compare our reviews carefully, or perhaps a reader with experience can share some comments.
Tom Posted Jan 27, 2019 6:21 PM PST
Is this Benq better than the Optoma Gt1080Darbee? It would be for mixed use PS4 games and BluRay movies. I'd use it in a bedroom and I hope I could project a 160-inch. Thanks to anyone who can help me to choose.
David Posted Feb 1, 2019 8:54 AM PST
Any possible plans to review the BenQ LK970 laser projector? I haven't been able to find a single review on that unit, but on paper it seems like it would blow away a lot of competing projectors.
Rob Sabin, Editor Posted Feb 1, 2019 9:18 AM PST
Nothing in the works right now, David. But we'll keep it in mind. We do have BenQ's HT9050 in our schedule, which is their new model using Philips's LED light engine.
A Torgersen Posted Mar 28, 2019 5:55 AM PST

Had this a few months now, and am overall very pleased with the purchase, bright enough even for Tv-watching in the afternoons, a lot of fun watching cartoons with the kids and great for late movie-nights. The occasional flicker when adjusting to bright scenes had me wondering though, if it is a sign of failing bulb or something with the light-sensor not working as intended. Occurs when changing to bright scenes or a portion of the picture is very much brighter than the rest, also when displaying static slideshows using a Chrome-cast ultra.Also tried experimenting with the LumiExpert on and off, still makes no difference best regards, A Torgersen, CZ
Mike Posted Apr 2, 2019 8:08 AM PST
Try switching between the lamp modes. I'd guess you're on SmartEco... I've seen a little bit of the same issue when a scene is bouncing back and forth between a bright image and a dark image. I've narrowed it down to SmartEco making quick adjustments on the brightness. It's rarely bothersome, but just setting it Eco or Normal lamp modes always seems to resolve it.

BenQ customer service has been awesome! They did release a firmware update to fix the LumiExpert studder and it is running smoothly.
Nathan Posted May 3, 2019 12:30 PM PST
Good Day,

I have looked at a few websites and reviews but cannot find, or at least not that seems to be, an answer to the following question. Can this projector be mounted behind the screen for rear projection?

Thank you.
Rob Sabin, Editor Posted May 3, 2019 1:22 PM PST
Nathan, this information in right there in the user manual, which is available for download on our database page for this projector if you use the Feature Search link on the homepage or type the model into the search engine.

The answer is that it has settings to accommodate either a low rear screen mount or a rear screen ceiling mount (with the projector hung upside down) along with the usual low front and front ceiling mount settings.
Troy Olson Posted Jun 5, 2019 4:11 PM PST
Exllent projector. Easy to use and an amazing picture for the price. Best projector I've ever owned. Short throw works perfect so I don't need a big room for a big screen. 100" is perfect in my little living room. Perfect for parties and gatherings.
Francine Posted Sep 9, 2019 1:27 PM PST
Recently purchased this unit through Telus and I LOVE the sharpness /picture quality! And my step son loves it for his video games!

Easy to set up and fairly light weight with the built in speakers that fill the room with clear audio! Very nice unit!
Robert Baggs Posted Oct 3, 2019 4:24 PM PST
On my Benq short throw, am I able to change the tint or hue. If so, then how. Thank you88
Rob Sabin, Editor Posted Oct 6, 2019 12:09 PM PST
Robert, please visit the ProjectorCentral database product page for this projector and download the user manual to find the tint/hue control if you can't see how to access it. It is usually among the primary controls in the first layer of the Picture or Image menu on any projector.
Artem Sorokin Posted Nov 6, 2019 11:03 AM PST

Can anyone help me with LumiExpert thing? I'm experiencing brightness flickering during changing of bright-dark scenes. How can I resolve it? LumiExpert is turned off (always), Lamp Mode is Normal either Economic. I've seen a comment, that there is a firmware with fix, but I was not able to find any firmware on BenQ's website.

Thank you!
Thai Posted Apr 20, 2020 5:12 PM PST
Hi there, I too am also experience the flicker and have tried to check all the settings. Any help I could get here?

David Leff Posted Apr 20, 2020 5:59 PM PST
Question on the usb A for wireless dongle. Can this unit be used wireless or am i reading this wrong. Will be connecting two devices to projector a computer and cable tv. Trying to see options for connecting said devices. if hdmi wires is there any that everyone prefers for running through attic in uncontrolled temperature changes. NJ have hot and cold seasons
darren mulcahy Posted May 17, 2020 12:22 AM PST
I've just bought a brand new Th671st and I'm having terrible flickering issues when the lamp is set to anything other than normal mode and it's driving me nuts.....Any help greatly appreciated. Is there a firmware fix for this as I've not come across one on the Benq site
Vijay Raman Posted May 22, 2020 8:39 AM PST
David, Why does the brochure /description on benq and amazon website say "5W stereo speakers?" Then if there is only one speaker, can it be stereo? Thanks.
Rob Sabin, Editor Posted May 22, 2020 8:45 AM PST
Vijay, BenQ and other manufacturers issue these spec sheets very early in product development and the reality is they are often wrong but live on without correction. Check their website to see if the specs there also reflect a pair of stereo speakers (which they do offer in some home theater projectors). But either way, be aware that the internal speakers in most projectors are really just there for a pinch and you should always plan on a standalone powered speaker or audio system.
Malcolm Adams Posted Aug 25, 2020 8:54 PM PST
Can this projector be used with a 16:10 aspect screen? Could be a great fit with my golf sim project with 10 feet throw. Thx
Nichole Posted Nov 23, 2020 5:54 PM PST
Is this projector a better option than the Optoma HD39HDR ? I am looking for an excellent long lasting projector for home theatre use under $1,000 ideally. May be willing to pay more for a 4K quality picture. What is your recommendation? I have been searching through reviews for far too long and still cannot figure it out. Any help appreciated! You guys are the experts and I just am looking to set up a nice place to watch movies as a novice home theatre set up.
David Milsom Posted Jan 21, 2021 3:18 AM PST
I love this projector my only issues were the shuddering on 24fps makes blu-ray unwatchable in fight scenes and if using the usb to power a chromecast etc the screen would split at times into an upper and lower half. That said compare to my old z3 or even older samsung projector and the picture is stunning

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