We in the industry, were so excited. You can present in an auditorium with 110 lumens! Well, sure, in near complete darkness, but that's how presentations were being done, all slide presentations and much of everything else. Those projectors were VGA - 640x480. Price tag was many thousands of dollars.
Fantastic! That was about 18 years ago. Now, we can, again, present - in an auditorium, no less, with a projector that fits into the palm of your hand, and runs on batteries Yes, you need the small battery pack, or AC to get the full 100 lumens. And the PK320 pico projector is even higher resolution at 1280x800.
I still own an XP8000 external battery pack. This nifty device should provide more than an hour of charge while pumping out about 100 lumens.
That battery pack was $99 when I first looked at it - the XP8000, which weighs (per Optoma) one entire gram more than the projector - 228, vs 227. Together - that's 455 grams - one pound is 454 grams. Bottom line - with the battery pack you have a 1 pound portable 100 lumen PK320 pico projector!
For a DLP Pico projector, the Optoma PK320 produced a satisfactory image. I've said that elsewhere in this review, and about other pico projectors.. While the PK320 image clarity is sufficient for many uses, including many types of presentations, it is definitely soft compared to any "full sized" projector - some of those weighing under 4 pounds. Keep in mind this is only a WVGA projector - 854x480 - the same resolution as an "old fashioned" DVD (which is about 1/5 the resolution of 1080p and Blu-ray. Here's a test image at 720p resolution that gives you a good idea how sharp the projector is (click the image for higher resolution): Chart image from the Optoma PK320 projector. Of course WVGA projectors are barely around in traditional projectors - just a few mostly for K-12 school purchases, those too will offer a sharper looking image. It's tough to create a great little projector with sharp optics and optical path. Small text is tough, but Powerpoint-like presentations can be just fine, with their larger type and graphics/images. You don't want to be doing spreadsheet work!
There is almost little to no light leakage. Like other pico projectors, the buttons only light up for a few seconds while navigating around the projectors features and very little light leaks through other open areas of the projector. Overall, internal reflections may have something to do with the image softness.
Because of the light technology being used, the projector produces no sound when on battery. A very low level fan noise when operating on AC power, or with the battery pack.