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40 hours a week for about 10 years before the light engine will fail, so you’ll be replacing the projector for being outdated well before that moment.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.