The Asus S1 is slightly larger and heavier than the smallest projectors, but goes almost in the trouser pocket and slides smoothly into a handbag. The built-in 6,000 mAh battery lasts for around 3 hours. It can also be used as an emergency charger for mobile phones. The projector does not read video files, but has an HDMI input that also supports MHL for Android phones.
For just 50 bucks more than the Philips PPX5110, the Asus S1 provides a significantly better picture experience. The resolution is the same, and round objects may look somewhat serrated, and S1 is not optimal as a text viewer. But for video it works quite ok, with about the same resolution as the old picture tube TVs.
The brightness is in a completely different league than PPX5110, and here you actually see the picture in all the scenes, even if you do not necessarily have it darkened in the room. Though, as always, it pays to draw the curtains. Doctor Strange provides a good picture experience, and the colors look neutral and nice. No burgundy faces here. The black level is a bit paler than, for example, Philips PPX3417, and the images are therefore somewhat flatter. But we think the compromise works well, and we like the extra brightness. The projection distance is short, here you get a 41 inch image from just one meter away, which is very good.
The 2 watt sound is louder than many of its competitors, which only have 1 watt. Of course, it gets much better with a speaker, which can be connected via the headphone output.
The Asus S1 is a compact travel projector with 200 Lumens, and is among the brightest in its class. It does not have the best black level, but with natural colors and short throw distance combined with a good battery life, the compromise is still one of the best we have come across in this price range.
That you can use the projector as an emergency charger for your mobile is a nice bonus, but not something we have emphasized.