Our take
The BenQ TH671ST is a Full HD lamp projector that combines a stated 3000 ANSI-lumen rating with a 0.69–0.83 throw ratio and 16.7 ms input lag at 1080p60. Its optical design is short throw rather than ultra-short throw, so the lens still needs measured distance from the screen. BenQ lists a small built-in speaker and wired source connections, not an app platform. The model suits gaming or home video when the room can accommodate its lens distance and lamp-based AC design.
A gaming or movie room that needs native Full HD and a shorter screen distance with enough space for a conventional short-throw lens.
It is not for battery use, wall-adjacent ultra-short placement, built-in streaming, or a buyer who needs optical lens shift for a fixed off-center mount.
Pros & cons
What could work for you, and what to consider before buying.
What works in its favor
- Native 1920 × 1080 and 3000 ANSI lumens give buyers two clearly stated core specifications.
- A 0.69–0.83 throw range makes it easier to produce a large image in a shorter room than standard-throw designs.
- BenQ specifies 16.7 ms input lag at 1080p60 for responsive game input.
What to weigh up
- The model remains a lamp projector that requires AC power and unit-specific lamp checks.
- Its short-throw ratio is not an ultra-short-throw wall-placement solution.
- A 5 W speaker is basic room audio, and the source set does not establish streaming apps.
The key details
| Model covered | TH671ST |
|---|---|
| Image format | Native Full HD 1920 × 1080 with 3000 ANSI lumens |
| Rated light output | 0.69–0.83 throw ratio, 1.2× zoom, and no lens shift specified |
| Placement | Lamp illumination, 5 W speaker, HDMI/MHL inputs, and 16.7 ms 1080p60 input lag |
Performance figures are manufacturer claims. Source checked October 7, 2026. Regional models and included accessories can differ.
What the features mean for you
Short throw can solve a real room-distance problem
BenQ specifies a 0.69–0.83 throw ratio with 1.2× zoom, allowing a useful image from a shorter lens-to-screen distance than many standard-throw home models. That helps in a room where a rear ceiling mount would be too far away or where viewers might walk through the light path. It does not mean the projector can sit directly below the screen; measure the screen width against BenQ’s distance chart. A short-throw lens can also be sensitive to small placement changes, so allow room for final adjustment and keep the surface stable. The TH671ST has no lens shift in the cited specification, which makes physical positioning more important. Treat the ratio as a placement tool, not as a generic promise of a very large image in every room.
Full HD and ANSI brightness suit movies and games
The native 1920 × 1080 panel is a straightforward match for Full HD film, console, and streaming-device output. BenQ rates brightness at 3000 ANSI lumens, giving the buyer a manufacturer-labeled figure to compare with other ANSI-rated models. That number does not guarantee identical appearance at every screen size: lamp mode, calibration, screen gain, lamp age, and ambient light affect the picture. A modest screen in a room with controlled light is a more predictable target than a large image in direct daylight. The model does not use a laser light source, so the expected output and service needs of the lamp should be evaluated on the exact unit. Native resolution and a published ANSI rating are useful facts, but viewing distance and room conditions still decide whether the image looks satisfying.
Low input lag is relevant to a game setup
BenQ specifies 16.7 ms input lag at 1080p and 60 Hz, a figure that can matter to players who notice delay between a controller and the on-screen response. It should be understood under that stated signal condition rather than generalized to every refresh rate, resolution, or processing mode. Connect the console through a compatible HDMI input, select the appropriate picture mode, and check the full video chain if an AV receiver or capture device is involved. The specification makes the TH671ST more attractive for responsive casual gaming than a projector with no published timing figure. It does not make the device a gaming monitor, and lamp brightness, motion handling, screen size, and room light remain part of the experience. Buyers with competitive requirements should verify the exact input mode and source setup before committing.
External sources and sound keep the system flexible
The TH671ST has HDMI inputs, including MHL support on the documented connection, and a 5 W speaker. Those features cover basic playback, but the small speaker is a convenience for temporary use rather than a substitute for a soundbar or receiver in a dedicated room. BenQ’s materials do not establish a built-in streaming operating system, so connect a streamer, console, or computer as the source. Check how audio passes from the chosen device and whether an external speaker can sit near the screen. A separate source makes app compatibility independent of the projector, though it adds cables and power requirements. Plan these pieces together so a short-throw placement does not leave awkward source access or audio routing.
Lamp condition and placement are part of the purchase
The TH671ST is AC-powered and lamp-based, so its model specifications say nothing about remaining lamp life in an individual unit. Ask for operating hours and service records, inspect the image for color uniformity and dust, check focus at the edges, and confirm every required input before buying used equipment. Measure the room and screen before choosing a mount because the short-throw lens gives less placement distance than a conventional model but still needs a defined range. The adjustable foot and keystone options can help a temporary setup, but are not optical lens shift. Compare another projector if the room requires wall-adjacent placement, a quieter all-in-one streamer, or a battery. The TH671ST is strongest when low-lag Full HD and a measured short throw are the deciding criteria.
What else to compare
For a native Full HD model with a longer conventional throw and two-axis lens shift, compare the BenQ HT5550; for an ultra-short-throw classroom setup, compare the NEC NP-UM351W.
Before you buy
Is the TH671ST native Full HD?
Yes. BenQ specifies 1920 × 1080 native resolution.
Is it ultra-short throw?
No. Its 0.69–0.83 ratio is short throw, but it still needs a measured lens-to-screen distance.
What input lag does BenQ specify?
BenQ lists 16.7 ms at 1080p60.
Where can I check the current price?
Use the Amazon link for current offers. Check the exact model, seller, product condition, delivery, and return terms. This page does not display a live price or confirm stock.
Sources & review basis
We use the following manufacturer documentation for the product features above. Our suitability notes and buying advice are editorial judgments based on those features, not measured performance results.
- BenQ TH671ST official specifications ↗ — checked October 7, 2026.
- BenQ TH671ST official specifications ↗ — checked October 7, 2026.
- BenQ TH671ST official user manual ↗ — checked October 7, 2026.
The decision
The TH671ST fits a gaming or home-video room where Full HD detail, an ANSI-labeled output figure, and short-throw placement align. Verify distance, lamp hours, source compatibility, and external audio needs.
Is it the right fit?
Check the exact model and today’s offers on Amazon.