With the ASUS S1 Pocket Projector, ASUS has managed to shoehorn a surprisingly capable projector into a nearly rectangular block that's small enough to fit on your palm. It even looks good, with a silver metal case, rounded corners, and a high quality fit and finish. Like most projectors this size, it's built around a DLP chip and an LED light source. Also like most, it's meant for both casual home use and for business presentations on the go. The native 854x480 resolution, with its 16:9 aspect ratio, seems targeted more for home than business, but the 200-lumen brightness rating, measured at 150 lumens, makes it bright enough to be useful in either role.
Note that the only input is MHL-enabled HDMI. That makes it easy to use with an MHL-capable phone or tablet, but also means you may not be able to connect it to your laptop. Assuming you can connect it, however, it can be a highly useful traveling companion, and nearly an impulse buy, at $319.99.
Like most projectors in its size and weight class, the S1 is built around a DLP chip that's designed to maximize brightness, but also adds apparent scaling artifacts. The artifacts are most obvious as added patterns in areas filled with repeating patterns of dots or fine lines. They can also give images a soft focus look.
You'll see similar artifacts with any DLP or LCD projector if you use an input signal that doesn't match the projector's native resolution. With the S1, however, they also show up at the native 854x480. Fortunately, this isn't necessarily a problem. If you don't use patterned fills in graphics, you may never see the artifacts, and even if you see them, you may not mind them.
The S1 has an advantage as well, compared with higher resolution models with the same issue. If 854x480 is the appropriate resolution for your needs, you probably won't be showing images with a level of detail that will be noticeably affected by a slightly soft focus. And given the SD resolution, you're not likely to notice any effect in video or photos either.
Rainbow artifacts (flashes of red, green, and blue) are another potential issue for any DLP projector. With the S1, I saw them infrequently enough with data images that it's unlikely anyone will find them bothersome. With video, I saw them often enough that anyone who sees them easily will notice them, but infrequently enough that few should find them annoying.
Also demanding mention is that the S1's color brightness matched its white brightness in my tests. That's notable because many DLP projectors, including models that use LEDs, have significant differences between the two, which can affect both color quality and the brightness of color images. Having the same value for both means you don't have to worry about that possibility.
Data image quality. In most other ways data image quality was impressive for a projector in S1's size and brightness range. Color balance was excellent, with definitively neutral grays at various levels from black to white in all predefined image modes. Color quality was just as good, with vibrant, eye-catching color in all modes. More important for data images, the S1 handled detail well enough for any images you're likely to use an 854x480 projector for, including PowerPoint slides. White text on black, for example, was crisp and readable at 9.0 points, and black text on white was easily readable at 7.5 points, despite a minor soft focus effect.
Video quality. Although the S1's video quality is limited by its native SD resolution, its (nearly) 16:9 aspect ratio at least lets it take full advantage of the resolution it has with widescreen video. Colors are within an acceptable range, as long as you're not too much of a perfectionist. However, the predefined Theater mode has obviously better color than the brightest mode, which tends to give skin tones a green tint. That basically leaves you a choice between noticeably better color and a larger usable image. Colors also tend to be a little flat, as you would expect from a low contrast ratio.
On the plus side, the projector did a good job with shadow detail, even with clips that many data projectors have problems with, and it showed only a hint of posterization in scenes that tend to cause that problem. As long as you don't see rainbow artifacts easily, or don't mind seeing them occasionally, the video is more than watchable for long sessions.
Setting up the Projector
Limited Connectivity. The back panel on the S1 offers only three connectors:
1 HDMI, MHL enabled for easy connection to an MHL-capable phone or tablet.
1 mini-plug audio out
1 USB A (For providing power to a USB device)
Keep in mind that you can connect between the HDMI port and a DisplayPort, Apple Lightning port, or a DVI-I or DVI-D port. If you don't have at least one of these on the image source you want to use, however, you won't be able to connect.
Setting up. Assuming you have an appropriate connector on your image source, setting up the S1 is easy. Plug in the cable, turn the projector on, point it at the screen, and focus. Using the power cord is optional, assuming the S1's battery is charged.
One welcome touch is that the focus ring moves more than is typical with small projectors before you'll see a significant change in focus. That makes it easier than with most models to find the best setting. Another plus is that the two rubber feet--one all the way across the front and one across the back--do a good job of holding the projector in place. Most small projectors pivot away from the screen easily if there's even the slightest tension on the cables.
As with most projectors this size, there's no zoom, so you have to move the S1 to adjust image size. For most of my tests, I used a 52" diagonal image with the projector 45" from the screen.
Note too that the S1's vertical offset lines up the bottom of the image with the center of the lens. That works particularly well if you're using a table-top screen on the same table as the projector. If you need to adjust the image position and don't have a tripod, you'll need to tilt the projector up or down by putting something under its front or back edge. If you do that, however, you won't be able to square off the image, since there's no keystone adjustment.
Highly portable. The S1 measures 1.2" x 4.4" x 4.0" (HWD), and weighs just 13 ounces with its rechargeable battery. That may be all you need to carry, since the fully charged battery is rated at 3 hours in the S1's Battery mode. Add the power block, supplied HMDI cable, and soft carrying case the S1 comes with, and it's still only 1.75 pounds.
Low running costs. ASUS rates the light source at 30,000 hours, which means it should last the life of the projector.
Surprisingly capable audio system. The 2-watt mono speaker offers good sound quality and enough volume for a small room. You can also plug a headset or external audio system into the mono audio output.
Brightness. Using AC power, I measured the S1 at 150 lumens in its brightest predefined image mode and at 127 lumens in Theater mode. That makes it bright enough for a 30" to 35" image for extended viewing in moderate ambient light, or a roughly 45" to 65" image in theater dark lighting. The 52" image I settled on for testing is also quite watchable for short sessions in moderate ambient light.
Using battery power, the brightness dropped to 108 lumens in Presentation mode and 71 lumens for the low power Battery mode. That translates to being suitable for roughly a 20" to 25" image for long sessions in moderate ambient light.
Good brightness uniformity. The projector did an even better job maintaining uniform brightness than its 78% uniformity measure suggests. The dimmest and brightest areas were far enough apart, with the brightness changing gradually enough, that I couldn't see any difference even with a solid white screen.
I've already touched on all of the S1's limitations worth mentioning. All but one are typical for this category of projector.
No zoom. Like most small projectors, the S1 lacks a zoom lens.
Apparent scaling artifacts. As with all projectors with a similar DLP chip design, the S1 shows apparent scaling artifacts even at its native resolution.
Rainbow artifacts. As with the vast majority of DLP projectors, the S1 shows occasional rainbow artifacts.
Limited connection choices. You can only use image sources that can connect to an HDMI port.
The ASUS S1 sits in a comfortable niche between competing pocket projectors that are similarly portable but not as bright, and 300- and 500-lumen models that are brighter, not as portable, and more expensive. Unfortunately, if you need to use an image source that can't connect to an HDMI port, it's useless. But if HDMI will work with everything you need to connect to, the S1 delivers a winning balance of image quality, portability, brightness, sound quality, volume, and price. That's more than enough to make it an attractive choice.
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