One way that the 850 SW improves on the 790 SW is in its overall performance. The 790 was pretty good in this department, but the 850 is even better. It starts up in about the same time, a very respectable 1.5 seconds, while in single-shot mode its shot-to-shot time is approximately 1.9 seconds, a little quicker than the earlier model. In continuous shooting mode with a H-type high-speed xD card it can maintain a shooting speed of just over one frame a second, although using the slower M-type cards limits this to a burst of three frames before the camera has to pause to write to the card.
The autofocus system is very good, focusing quickly and accurately in good light, and only slowing down a bit in lower light conditions. Low-light focusing without the LED lamp is not the best I’ve seen, but nonetheless it copes well with most situations. The Bright Capture system brightens the monitor in low light conditions, making it much easier to frame your shot.
I was reasonably impressed by the image quality of the 790 SW, but unfortunately the 850 SW seems to have taken a bit of a step backwards in this department. Image noise, or rather the effect of the heavy-handed noise reduction system, is visible in all shots over 100 ISO, blurring fine detail and reducing overall picture quality. Colour reproduction is rather muted, with even shots taken in bright sunshine looking dark and muddy. I thought this might be an effect of the contrast-limiting Shadow Adjustment option, but even with this feature turned off, colours are still disappointing.
The lens performs fairly well, with adequate centre sharpness, and the camera seems to remove wide-angle barrel distortion in processing. This results in nice straight parallel edges, but does produce some blurring in the corners of the frame. However it is pleasingly free from chromatic aberration and purple fringing.
Although the mju 850 SW continues the rugged tradition of its predecessors, with bomb-proof build quality, attractive design and excellent overall performance, its restricted zoom range and limited list of features are starting to look a bit dated in today’s market. At £155 it is attractively priced, but compared to the superior photographic capabilities of the Pentax W60 it looks a bit weak, and its relatively poor picture quality is also a disadvantage.