Pentax continues its journey through the alphabet with the Optio S5z, which replaces the popular Optio S5n, in turn a replacement for the S5i. Once again, the principle change is an increase in the size of the LCD, which has grown from 46mm (1.8 inch) on the S5i to 51mm (2.0 inch) on the S5n to a camera-dominating 64mm (2.5 inch) on the S5z. This is surely the end of the line, though: not only does the 'z' appellation leave little room for further upgrades, but also it's hard to see how it would be physically possible to put an even larger screen on this small camera.
Other changes include the replacement of the Optio S5n's docking station with a simple battery charger and a new Comment space function that leaves a blank strip along the bottom of your photo, so you can add handwritten notes.
Measuring 83 by 55 by 22mm, the Optio S5z is 3mm taller than the S5n, but it's still just possible to hide it behind a credit card. With battery and SD memory card in place, the S5z weighs 124g. Note that Pentax doesn't include a memory card with the camera, so you should budget for purchasing at least a 128MB SD card. If you want to record movies, get a fast 512MB or 1GB card.
The 64mm LCD takes up most of the back, leaving only a narrow strip on the right-hand side for the other controls. Consequently, all the buttons are small, with the smallest one measuring just 2.5mm across. That said, we like the use of four separate direction buttons around the central OK button, rather than a five-way rocker switch. There's only one place where you can rest your thumb, about one third of the way down the right-hand side, and all Pentax provides by way of a grip is five tiny rubber dots. The aluminium alloy front is stylish but slippery, so you'll want to use the supplied wrist strap at all times -- otherwise you'll risk dropping the camera.
The big LCD is bright and contrasty, making it usable even outdoors, although in bright sunshine we sometimes wished for an optical viewfinder. Although the LCD is significantly bigger than the one on the S5n, the resolution is unchanged, so you don't see any more detail -- you just get a bigger picture.
We were disappointed that the S5n's docking station has been replaced by a simple battery charger. The new arrangement is better for travellers, because there's less to carry, but it isn't as convenient for day-to-day use. With the S5n, you just dropped the camera into the stand to recharge the battery; now you have to take the battery out, put in the charger and then remember to put it back in the camera before you go out.
We were pleased to see that Pentax has retained the neat sliding doors that protect the USB and DC-in ports. They look good, aren't as fiddly as rubber port covers and seem unlikely to break or get lost.
The Optio S5z has the same 3x optical zoom, 36-to-107mm (35mm equivalent) lens as the S5n. A wider wide-angle setting would be useful for photographing interiors and groups of people, but the range is about normal for an ultracompact. In macro mode, the closest focusing distance is 180mm; Super-macro mode reduces this to 60mm.
The camera powers up in capture mode. Press the OK button to cycle the LCD through four different display options: basic settings, detailed settings including a (small) live histogram, rule-of-thirds framing guide, and no settings. The autofocus area is marked in all four displays and when you half-depress the shutter button to focus the lens, the display shows the selected focus point, the shutter speed and the aperture. The default option for the autofocus is a wide area spanning the centre of the image, containing three separate focus points, but you can set it to use only the central focus point if you prefer.