Pentax's 2005 entry compact — 4MP CCD, 3x sliding-lens zoom, 2.5in screen, AA power
The Pentax Optio S45 was an entry-level digital compact announced in May 2005 together with the 5-megapixel Optio S55. Both developed the earlier Optio S40, keeping the AA-powered, all-metal formula while adding a larger screen. It is a separate model from the S40, S50 and S55 around it in the range.
It pairs a 4-megapixel 1/2.5-inch sensor with the 3x SMC Pentax zoom built on the company's Sliding Lens System, which lets the optics collapse into the slim 89x58.5x27.5mm body. Images up to 2304x1728 pixels are composed on a 2.5-inch LCD, video records at 640x480 and 15 frames per second, and twelve picture modes cover subjects from portraits to night scenes. Power comes from two AA batteries or a single CR-V3 lithium cell, and the camera weighs about 180g.
This was a family snapshot camera and it still works best in that role: simple mode-driven operation, a usefully big screen for its day, and AA power that any household can feed. Four megapixels remain plenty for prints and sharing, though low light pushes the small sensor quickly into noise.
AA power means no charger hunt — just check the contacts for leakage corrosion and use fresh NiMH cells, as alkalines drain quickly with the screen and flash. Confirm the sliding lens deploys and retracts smoothly, the SD-type card slot reads reliably, and the large screen is unscratched. Sellers frequently mislabel S40, S45, S50 and S55 bodies, so verify the badge.