The A40's overall performance is very good. It starts up in just under three seconds, which is a little slow, but not intolerable. It shuts down again a bit more briskly in 2.5 seconds. In single shot mode the shot-to-shot cycle time is very quick at about 1.2 seconds, while in continuous shooting mode it can maintain a speed of just under two frames a second, not bad for a 12MP camera. The autofocus system is a lot quicker than some of Pentax's previous efforts, and although it isn't as fast as Casio or Canon AF systems it isn't painfully slow, and also doesn't slow down much in low light or at longer focal lengths. Low light focusing is very good, and the AF assist lamp means it will focus fairly reliably in total darkness at a range of about three metres. Flash exposure is also very good, producing even exposures at close range and filling a large room easily. Battery duration isn't too bad either, managing to squeeze about 200 shots out of the small 710mAh Li-ion battery.
Image quality has never been a major problem for Pentax's high-spec cameras, and here the A40 shows its class. Focusing, exposure metering and colour reproduction are all excellent. The lens quality is also up to Pentax's usual high standard, with superb sharpness from edge to edge and no chromatic aberration. It does produce some barrel distortion at both ends of the zoom range, but it is fairly even. Noise control is about average for a 12MP compact camera, with very good picture quality up to 200 ISO, and then progressively lower quality from the just-about-printable 400 ISO to the pretty ugly maximum of 1600 ISO. With the Dynamic Range Adjustment set to strong or automatic, the A40 coped very well with high contrast lighting, keeping a good amount of shadow detail and not too many blown highlights.
Hopefully the Optio A40 doesn't represent the last generation of Pentax compact cameras, because despite its ultra-compact size it is packed with clever technology, including effective image stabilisation and dynamic range improvement. Build quality, design, performance and image quality are all very good, and the camera is easy and satisfying to use. It may be expensive at the moment, but it offers a very complete and attractive package, and compares well in quality and performance with the very best of the competition.