A portable projection device comprises a housing, a handle, and an optical engine. The optical engine comprises an illumination source, an imaging system, and a wide angle projection lens that includes a first lens group of negative refractive power, the first lens group having at least one aspheric surface, a second lens group, and a third lens group of positive refractive power. For the wide angle projection lens, the following Conditions (1) to (4) are satisfied: |F.sub.1/F|.gtoreq.4.5 (Condition (1)); 2.5.ltoreq.|F.sub.2/F|.ltoreq.6.0 (Condition (2)); 3.8.ltoreq.|F.sub.3/F|.ltoreq.5.0 (Condition (3)); and 0.8.ltoreq.BFL/F.ltoreq.1.4 (Condition (4)). The portable projection device can be implemented as a personal gaming system and can also be configured as a portable, fully integrated video gaming system that allows gamers to plug in and play at nearly any location, with only a wall or other viewing surface being used to view the projected image.

 
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> Imaging method for a capsule-type endoscope unit

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