Pentax's ultra-slim compact — 5MP CCD, 3x sliding lens, SD storage, 105g, announced 2004.
The Pentax Optio S5i was announced in August 2004 as the follow-up to the popular Optio S4i, adding an extra megapixel, minor restyling and a few new features. It sat in the credit-card-sized end of the Optio range, built around the sliding-lens trick that made the original Optio S famous.
It uses a 5.0-effective-megapixel CCD behind a 3x optical zoom covering a 35.6-107mm equivalent range, with a 1.8-inch LCD on the rear. Pentax's sliding lens mechanism lets the optics retract into a body only 20.5mm deep, and the whole camera weighs about 105g without battery. Storage is on SD cards, power comes from a proprietary rechargeable lithium-ion battery, ISO runs to 400, and it records 320 x 240 movie clips at 15fps.
This is a true shirt-pocket camera for casual snapshots and travel, and a neat example of mid-2000s miniaturisation. The small body means small controls and no viewfinder comforts beyond a basic optical tunnel, so it favours point-and-shoot use over deliberate manual work.
Used examples depend on the proprietary D-LI8-type lithium-ion battery, so check it holds charge and that a charger comes with the camera. SD storage keeps cards easy to find. Verify the sliding lens extends and retracts cleanly, since a knocked lens assembly is the common failure, and inspect the LCD for scratches as there was no cover glass to spare.