Pentax's 2005 aluminium compact — 5MP CCD, 36-107mm 3x zoom, 2.5in screen, AA power
The Pentax Optio S55 was announced in May 2005 alongside the 4-megapixel Optio S45, both developed from the previous year's Optio S40. It was the better-specified of the pair, a 5-megapixel AA-powered compact with an aluminium alloy body pitched at everyday family use.
The 5-megapixel sensor sits behind a 3x zoom equivalent to 36-107mm, built on Pentax's Sliding Lens System so the optics collapse into a slim body. A large-for-the-era 2.5-inch LCD handles composition and review, and images go to SD-type cards. Power comes from two AA batteries, which period reviewers noted the camera drains fairly quickly when the screen and flash work hard.
As a used buy the S55 is a friendly, no-surprises snapshot camera: aluminium shell, big screen, familiar controls and nothing proprietary in the battery compartment. It suits beginners, children learning photography, and anyone wanting a cheap CCD-era digicam for casual colour. Low-light work is not its strength, so keep it to daylight and flash range.
Check the battery door and contacts for corrosion from leaked alkalines and budget for NiMH rechargeables given its documented appetite for power. Confirm the sliding lens deploys smoothly, the 2.5-inch screen — the only finder — is free of scratches and dead pixels, and a small SD card is recognised, since large modern cards may not be. Distinguish it carefully from the S45, S50 and S5i when comparing listings.