TK705i vs TK705STi

Flexible Zoom or a Shorter Room? Measure the distance from your planned projector position to the screen before choosing. The TK705i gives you optical zoom from farther back. The TK705STi makes a large picture in a shallower room, but its fixed lens leaves less room for placement mistakes. Most of the headline smart-TV and gaming features are shared.

The choice that matters

Choose the zoom-equipped BenQ when your shelf allows flexible standard throw.

Choose the short-throw BenQ when limited room depth determines placement.

At a glance

The screen distance is the answer, not a footnote

For the same 100-inch 16:9 image, the TK705i's 1.0–1.3 throw ratio calls for roughly 7.3 to 9.4 feet from the lens, depending on zoom. The TK705STi's fixed 0.8 ratio needs around 5.8 feet. That can determine whether a bookshelf, table or ceiling position works at all. But measure from the actual lens, not the back of the projector, and leave enough space for ventilation and cables. If the seating area ends six feet from the wall, a projector needing eight feet is a nonstarter. If your existing mount is nine feet away and cannot move, the STi may produce the wrong picture size. The model name suffix describes a genuine different optical configuration, not just a minor accessory choice.

What you gain and lose with optical zoom

TK705i's 1.3x optical zoom lets you adjust image size from a fixed installation point without digital scaling. If you're renting and the shelf is already fixed in place, that zoom flexibility may save you from moving furniture or drilling another mount hole—provided the projector is within its permitted placement range. TK705STi has no equivalent optical zoom: the fixed ratio is a benefit only when the chosen lens distance is suitable. Both include manufacturer-listed automatic keystone assistance, but moving a corner electronically can cost effective image detail. Neither becomes ultra-short throw with a keystone adjustment. A dedicated UST such as Hisense PX3-PRO would sit near a specialized screen and needs a very different media-cabinet plan. Be clear whether you need six feet, eight feet, or mere inches from the wall.

Why the gaming and smart features don't decide this pair

The two projectors share 4LED lighting, 4K UHD output, Google TV, two 8W speakers and a 3,000 ANSI-lumen manufacturer rating. BenQ lists the same 5ms 4K60 input-lag proposition for each under its stated mode conditions. Neither should be called a native 4K120 projector merely because both have HDMI 2.1 connectors; their listed scan specifications remain 60Hz oriented. A 2K60 signal may be accepted but shown at 1080p60. These distinctions make a spec-sheet race unhelpful here. The person who wants family movies and occasional console games is deciding where a usable picture lands on the wall, not which sibling is fastest by an unsupported fraction of a millisecond.

Setting up without sacrificing the picture

Keep power-outlet location, power-cord path and airflow in mind. An ideal lens distance is useless if the projector blocks a walkway or its beam passes directly behind a standing person. At shorter throw, small positioning errors can make the image alignment more noticeable. Use the BenQ projection calculator with actual screen width, and favor physical alignment before heavy digital keystone. Verify the seller's model suffix, since many retailer thumbnails look nearly identical. An open-box TK705i is not the same as a new TK705STi, even if both headline Google TV and 3,000 ANSI lumens. Also confirm audio-return behavior for your soundbar and the app services you rely on rather than treating built-in Google TV as permanent license insurance.

What the numbers do not prove

These specifications come from manufacturer pages for the exact US model variants, not one controlled PIQSY laboratory comparison. Advertised brightness is not the light output measured in your preferred calibrated mode. An input-lag rating is valid only for its stated signal format and picture-processing conditions. The projector's underlying imaging hardware also must not be described as native 4K simply because the unit outputs a 4K UHD picture.

There aren't enough dependable exact-model US owner reviews to judge which sibling lasts longer. Check current seller prices, stock, included accessories and warranty; those details haven't been confirmed here. Those factors could change a purchasing decision without changing the underlying technical difference between the two projectors.

Who should buy each one?

Choose BenQ TK705i when: you have at least the longer lens distance needed for your screen and optical zoom would help adjust the final image size.

Choose BenQ TK705STi when: your room is shallow, the fixed 0.8 ratio matches the planned screen and you can put the lens in the correct position.

Choose neither when: your projector must be only inches from the screen wall or you need battery power. Neither sibling solves those requirements.

Before you buy

Mark the picture width and both lens distances with tape. Check the real cabinet or ceiling mount, not just the sofa-to-wall distance. Verify whether the seller lists the precise i or STi variant; confirm new-condition kit, cables and US warranty separately.

PIQSY conclusion

The TK705i is the more accommodating lens for a room with standard projection distance. The TK705STi is the simpler answer for a shallow room with a known fixed mounting position. Don't choose the STi just because 'short throw' sounds superior, or the i because zoom sounds premium. Put a 100-inch rectangle on your wall and see where the lens can physically go; that is the useful final switching rule.