Pentax announced the ultra-compact (in the most accurate sense of the phrase) Optio S at CES 2003 in January 2003. The Optio S measures just 83 x 52 x 20 mm (3.3 x 2.0 x 0.8 in) and weighs in at just 115 g (4.1 oz) ready to shoot, specifications we'd expect to see from an ultra-compact fixed lens digital camera, all the more amazing then that it has a three times optical zoom lens. Pentax has achieved this feat of miniaturization by altering the lens design so that when retracted three of the lens elements actually move upwards allowing the lens to take up less space. The only hint of this design from the outside is the vertically offset front lens element. The Optio S has a three megapixel sensor, lightweight Lithium-Ion rechargeable battery and stores images on SD / MMC cards.

Pentax Optio S sliding lens design

Lens at power off, note that three elements slide upwards out of imaging path thus a thin profile can be maintained
Lens at wide angle (elements back in the image path)
Lens at telephoto