Projector Reviews Images

Acer K138ST Pocket Projector Review – Summary

Posted on November 29, 2017 by Nikki Zelinger

Acer K138ST Pocket Projector Review – Summary: Summary, Competitors, Pros, Cons


The Acer K138ST is a short throw pocket projector with an LED light engine. That light engine can last up to 30,000 hours when used in ECO, and up to 20,000 hours at full power. That means you can run the projector roughly 40 hours a week for about 10 years before the light engine will fail, so you’ll be replacing the projector for being outdated well before that moment. The K138ST is a $599 pocket projector that has WXGA resolution (1280x800) – WXGA is basically the 720p of the business world. No matter – this Acer can accept HD content that is both 720p and 1080p, but it will output the 1080p as 720p. Typical.

There are five Picture Modes on the Acer K138ST: Standard, Bright, Movie, Picture, and Game. All modes are similar in brightness, with none of them meeting claim. That is typical – most projectors fall up to 25% short of claim. Acer claims 800 lumens, but in its brightest mode, Standard (not Bright, surprisingly), the K138ST measured 576 lumens. While that’s bright enough for a fully darkened room, it’s not quite bright enough to deal with a lot of ambient light, so you’ll want to make sure you have some control over how much light hits the projection screen (or wall). There are a few other projectors that may be better suited for you if you do not have control over your lighting conditions, but I’ll get into that in the next section.

Of the Picture Modes, Picture is the best mode. Standard has some good color, but it’s not quite as natural looking as Picture, which does a great job on both skin tones and the rest of the scene. I tried Movie Mode for about half of the photos of The Hunger Games before switching over to Picture. Below, I have a slider showing the difference in color between the modes, which were already featured on the Picture Quality page. As for the other modes – I didn’t bother. They’re all so similar in brightness (with all ranging from the mid-to-lower 500s to high 500s) that I don’t really see any reason to use anything other than Standard (when the room conditions are at their brightest) and Picture.

The Acer K138ST is simple in design, and is light-weight and portable. It comes with an attractive carrying case, and includes an AC power cord and brick, a remote control with battery, the Quick Start Guide, and a CD-ROM User’s Guide, as well as a VGA cable for connecting old-school computers. It has a fixed, manual focus lens with a lens cap in the front, an adjustable foot to tilt the projector (it has Keystone Correction to correct the image back to its rectangular shape when using this adjustable foot), and enough inputs and connectors for your home entertainment needs: an IR sensor for the remote control, a Kensington Lock slot, an Audio In and Audio Out, that VGA port, and a single HDMI.

This little pocket projector is loaded with features. It has wireless capabilities via the optional WirelessHD Kit and WirelessCAST, so you can project from a gaming console or Blu-ray player wirelessly, or project your smart phone or tablet’s screen using the K138ST. It is Bluetooth enabled, so you can wirelessly connect external Bluetooth speakers for better sound. It is 3D capable! That means you’ll be able to watch your favorite 3D movies, though I would suggest doing so at night. 3D eats up about 2/3 of the projector’s brightness, and the Acer K138ST doesn’t have a lot to work with. Oh, and the project has got game.

The Acer K138ST has an incredibly low input lag of 16.8 ms. That’s about half a frame behind, which is about as good as it gets with projectors. My Epson Home Cinema 5040UB, a 1080p pixel shifter that costs about $2000 more, has an input lag of 30.9 ms. It’s about one frame behind, and we can’t even detect that when playing online games, which is where you’d really notice something like input lag. That said, gaming on the Acer K138ST was an enjoyable experience – the games looked pretty good and gameplay was just as good as it is on my more expensive Epson.

The Competition

The Acer K138ST’s direct competition is the AAXA M6, which is the same price as the K138ST - $599. It is a 1080p, 1200 lumen projector with reasonably good color and a rechargeable battery. It has the same rated light engine life, a fixed lens, and an on-board media player. The AAXA’s focus ring is on the side of the projector, and is a small dial, instead of being on the lens itself like the Acer. It’s just as easy to control.

I favor the AAXA M6 for its resolution. I am a resolution snob (I’ll be the first to admit it), so the large pixels of the Acer K138ST really bum me out. I would say that the K138ST is the better choice, hands down, for color, features, and input lag (the AAXA M6 has an input lag that lives at the higher end of acceptable at 42.4 ms), but that 1080p resolution and higher lumen output is a clear winner in my book for those who have brighter room conditions. It also did not meet its claim (835 in its brightest mode), but the AAXA M6 has enough lumens to handle quite a bit of ambient light as compared to the Acer K138ST, which basically sucks at it.

They’ve got pretty much the same amount of inputs and connectors, although the M6 has a Micro SD card slot for sharing photos directly to the media player. You’ve got some trade offs here in terms of features, so I’m going to provide a list below of both the Acer K138ST’s and AAXA M6’s:

Acer K138ST Features

  • LED Light Engine – 20,000 Hours at Full Power
  • 576 Lumens in Brightest Mode – Not Good at Handling Ambient Light
  • 720p Resolution
  • 16.8 ms Input Lag
  • 3D Ready
  • Bluetooth Ready
  • Wireless Networking
  • No Rechargeable Battery
  • No On-Board Media Player
  • Better Color – No Real Adjustable Parameters to Customize
  • 3-Watt Stereo Speakers
  • 1 Year Parts and Labor Warranty

AAXA M6 Features

  • LED Light Engine – 20,000 Hours at Full Power
  • 835 Lumens in Brightest Mode – Can Handle Ambient Light
  • 1080p Resolution
  • 42.4 ms Input Lag
  • No 3D
  • No Bluetooth
  • No Wireless Networking (Does Have PC-Free Presenting via USB or Micro SD Card)
  • Rechargeable Battery
  • On-Board Media Player
  • Reasonably Good Color – Lots of Adjustable Parameters to Customize
  • 2-Watt Mono Speaker
  • 1 Year Parts and Labor Warranty

So, it will really come down to what is most important to you when deciding on which pocket projector to get. If you need a battery powered projector, the AAXA M6 is a good choice. If you need to connect Bluetooth speakers – go with the Acer K138ST. Neither projector is truly “better” than the other, only possibly better for your particular situation.

I mentioned that ViewSonic has a similarly priced projector – that’s the PJD-7828HDL, which Art is currently reviewing. We got to test it out after Eric calibrated it, and it has really great color. That one is a little more pricy, but not by much - $679.99 on ViewSonic’s website, though it can be found online for about $100 less, making it a direct competitor with the Acer K138ST and AAXA M6. The ViewSonic PDJ-7828HDL is a whopping 3,200 lumens, with full HD resolution and a loud 10W speaker. Now, this is a bright room projector, so it’s meant for rooms that don’t have a lot of control over ambient light and where the projector will be watched during the day – not so much for a fully darkened cave.

Epson also just released a few home entertainment projectors this year that are similarly bright. The Epson Home Cinema 1040 is a 3,000 lumen projector that costs $549.99 and comes with an MHL port for those streaming sticks like Chromecast, Amazon FireTV, Roku, etc. It is a 3LCD projector, so it has as many color lumens as it does bright ones, meaning an exceptionally vibrant image in the face of ambient light. The other three projectors mentioned are DLPs, which have lower color lumens than white ones. Neither of the two projectors from ViewSonic and Epson are pocket projectors, but they are quite small and portable. Either can easily fit in a backpack and are smaller than a 13” laptop.


  • WXGA resolution (1280 x 800) with 1080p maximum resolution
  • LED light engine life of up to 30,000 hours
  • DLP technology
  • 100,000:1 contrast ratio
  • 7x digital zoom
  • Manual focus
  • Short throw
  • Vertical keystone correction -20°/+20°
  • Large image – up to 100” diagonal
  • Lots of inputs and connectors
  • 2 stereo 3-watt speakers
  • 3D capable
  • Great for gaming (16.8 ms input lag)
  • Wireless LAN
  • Lightweight and portable at 1.65 lb
  • Comes with extras – box includes K138ST DLP projector, AC power cord, remote control with battery, Quick Start Guide, User's Guide (CD-ROM), attractive carrying case
  • One-year limited warranty on the projector with 90-days on the light engine


  • Did not meet 800 lumen claim (576 lumens)
  • No onboard media player
  • No rechargeable battery
  • No real way to customize color

© 2024 Projector Reviews

crossmenu linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram