Where the E40 does start to reveal its limitations is in overall performance. It takes nearly five seconds to start up, although it shuts down rather faster in just over two seconds. Shot-to-shot time is under two seconds for the first three or four shots, but then slows down noticeably as the image buffer fills up and has to wait until it has written to the memory card. Even using a high-speed SanDisk Ultra II SD card the average shot-to-shot time over ten shots was nearly four seconds. Likewise in continuous shooting mode it shoots the first three shots in under two seconds, but then slows right down to one shot every four seconds for subsequent exposures, and annoyingly the monitor screen remains black as long as the shutter is held down.
As with most low-end Pentax models, the autofocus system is quite slow, taking over a second to lock on in good light, and even longer in dim light. However the E40 is equipped with an AF assist lamp, and while low light focusing may be slow it is at least reliable, and will work in total darkness at a range of several metres. Other performance criteria are also adequate, including flash range, which is an excellent 4.3m at normal ISO settings, and the movie mode, which is slightly improved from the E30, and now offers a full 30fps at 640x480 resolution. Battery life also seems to be good, although as always with AA-powered cameras the actual performance will depend on the quality of the batteries used. Using the two standard alkaline batteries that were supplied with the camera I was able to take over 100 shots before the battery level indicator changed from three bars to two.
Picture quality is much improved over the E30, although it is still not without its problems, some of them quite serious. Exposure and colour rendition are better, and dynamic range is also good, especially with highlight detail, something that was a weak spot for the E30, however I found image noise to be a major problem at all ISO settings, even the minimum of 80 ISO. There was visible image noise in the darker areas of every shot, which robbed the images of a lot of fine detail and introduced colour irregularities. This is doubly annoying, because the new lens appears to be significantly better than the old one, with good edge-to-edge sharpness, no chromatic aberration and relatively little barrel distortion at the wide-angle end. However I did also notice some slight vignetting, with the corners of some wide-angle shots noticeably darker than the centre of the frame.
For a rock-bottom price the Pentax Optio E40 offers good build quality, elegant design and a surprisingly complete set of features. Performance is a bit on the slow side, but it will reliably take usable pictures in most lighting conditions. Where it falls down however is on final image quality, with noise problems at all ISO settings, and vignetting is also an issue.