Best in Class – Pocket Gaming Projector: Acer K138ST

Posted on November 6, 2018 by Art Feierman
Acer K138ST

Of all the projectors I’ve reviewed and that are included in this report, none have measured so well as the Acer K138ST when it comes to input lag. Input lag refers to the amount of delay in between the signal from your game console to the display (projector), and is measured in milliseconds. A handful of milliseconds probably doesn’t seem like it could really make a difference, but in the world of competitive gaming, it can mean the difference between life and death… of your character.

I’ve mentioned the scale of input lag several times already in this report, but just in case you’re hopping in on this page, I’ll do a brief refresher. 50ms is at the top of what is considered acceptable for input lag – for the typical gamer. It would not be tolerated by the most hardcore gamers who engage in competitions, often for cash prizes. 33ms to 40ms is considered good (again, for the average gamer), as these measurements translate to just over one frame behind on a 30fps game, two frames behind on a 60fps game. 16ms is considered to be the best measurement, and is about as good as we can get on projectors (for now). There are even faster gaming monitors on the market, for the total hardcore gamer.


The Acer K138ST is a $599.99 gaming projector with WXGA resolution – 1280 x 800 pixels – and has an input lag of 16.8ms. Until gaming on this projector, I didn’t notice much of a difference between projectors at 31ms (like my Epson Home Cinema 5040UB), and those that measured in the higher range of acceptable. Though those 33ms to 40ms+ projectors are a split second behind (literally), there appeared to be no time at all in between when I pressed buttons and when the action was displayed on my screen. Now I know better.

Best Pico and Pocket Projectors Report - Best in Class: Pocket Gaming Projector Acer K138ST

I’m not a competitive gamer, preferring to play my RPGs in campaign mode where no petulant children can annoy me by spewing incessant nonsense into the mic (real talk), but I could see how in online play, being a frame or two behind could be awful – especially if you’re playing against people who live and breathe Battlefield 1 (or any similar FPS game). Those guys are nuts – and gals. My friend Windi is so good at Battlefield 1 that I wouldn’t want to be anywhere near her on the opposing side of things. She games on a TV, but if she were to get a projector, I’d suggest she get one with an input lag around 16ms.

The Acer K138ST is another with an LED light engine that has a rated lifespan of up to 30,000 hours. Like the others, it has a fixed lens, so you’ll have to place it closer to the wall or screen surface to get a smaller image – as small as 25” – or further away to get a projected image of up to 100” diagonal. That’s sure to impress any of your friends who are still gaming or watching movie/TV content on their tiny-screen-TVs.

Acer claims 800 lumens for the K138ST, but it didn’t quite get there. This is a running theme of most projectors – it’s even acceptable for them to measure up to 25% below their claim. Hey, that’s why we measure and report on the lumen count for you – so that you can make sure the projector you are choosing will be bright enough for your room. It measured 576 in its brightest mode, which is, oddly, not named Bright, but Standard. Bright came in at 542, and is the second brightest mode. Both Movie and Game Modes measured 535 lumens, with Picture Mode measuring the least of them all – 532 lumens. Picture Mode is the projector’s best mode, as it has the best color handling on skin tones.

This projector has a few extras not found on all pico or pocket projectors. It is 3D ready, so you can watch your favorite 3D movies if you have them. It even comes with an attractive carrying case, one that reminds me of men’s toiletry/shaving bags for travel.

The Acer K138ST has wireless LAN capabilities, and you have two choices for doing so – WirelessCAST and the WirelessHD Kit. WirelessCAST is a dongle that allows for wireless projection from PCs and Macs. If you are running Windows XP (I know a few people who still do), you can project without audio, but Vista and above can project video with audio. It supports Mac OS X 10.8 or higher, iOS 7+, and Android 4.0+. The WirelessHD Kit is a dongle that hooks into the back of the projector and your gaming console or player, and allows for wireless communication between the two devices. A nice touch for us cord cutters.

This projector comes with stereo 3-watt speakers, which is plenty loud for movie watching and gaming. I tend to like when projectors have stereo speakers more than mono – just a preference. I think they sound better. It does have an Audio Out port if you do want to hook up external speakers such as a real AV surround sound system, or a fancy stereo rig. After all, this projector may have great sound for its size, but you can spend far more on good audio than a projector. Other than that, as far as inputs go, there’s one HDMI input, a VGA connector, a DC 5V Out port, and, of course, a DC connector for the power cable. The Acer K138ST comes with a standard 1 year parts and labor warranty, with 90 days on the light engine.

The Bottom Line on the Acer K138ST

Bottom Line: Natural looking color in Picture Mode, lightweight and portable with an attractive carrying case, long light engine life and the best of the best for gaming in the world of pocket projectors. An all-around awesome projector for college students and young adults who are looking for the immersive, big screen gaming experience on a budget. It’s great for travel, of course, and if you were to pair it with the NVIDIA Shield, you could easily take it in your carry on when flying, or pack it in a suitcase for other means of travel.

Acer K138ST Review

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