As often happens in the war between DSLR manufacturers, one suddenly steals a march on the others by introducing new features while also driving the prices down. I had nearly given up on Pentax just before the K10D appeared, believing that they had permanently lost the market to Nikon and Canon. This camera is revelation because it has the solid build and features of a £1000+ 'prosumer' rival for under £500; in fact it has decidedly more features.
There are modes galore, including the ability to three-way balance shutter speed, aperture and floating ISO number against each other. The ability to fine-tune colour temperature is a delight for indoor photography and, using the rear display panel, there is colour-bias 'moveable spot in a box' control built on top of that. I take a lot of pictures in places with truly horrible lighting, such as high pressure sodium illumination. I can adjust the image colour on the fly, so I go home with naturally lit images needing little computer correction. In all, the controls have evolved intelligently while somehow retaining a familiar feel from Pentax's first autofocusing SLR's in the 1980's. Controls and functionwise, there's far too much to describe here, needless to say.
The camera feels solid and ergonomically well laid out. Its shape also fits snuggly in the hand. I bought the battery grip with the camera. This provides a compartment for a second battery and a spare SD card but also has duplicate shutter button, as well as shutter speed and aperture dials. These are arranged for use when the camera is held sideways for portrait shots. All the camera's opening panels are rubber sealed. Several have fiddly little twist locks which are a begger to find in low light.
My camera came with an 18-55mm lens which looks well built. Two features caught my eye, which may seem trivial but which are important. The first is that the lens can be manually focused without having to first fiddle about switching off the autofocus at the camera; there appears to be a disengagement 'clutch'. Secondly, the lens filter size is just 52mm. Hooray, that means I can buy cheaper filters and use my existing set collected over several decades. (The lens on my last DSLR took a whopping 62mm filter.) However, there is a problem with this lens; its edge definition at open aperture is truly terrible. I suppose I should take a star away from the rating for this but this type of lens is just a cheap afterthought with cameras like this. I just put it aside and fitted one of my existing Pentax-fit lenses instead.
The shake reduction feature of the camera is truly excellent. I took a series of handheld images in a chapel, down to 1/15th of second, and all came out sharp. Because the shake reduction is in the camera body, every lens you fit has the benefit...even my old 1970's lenses. These work on fixed aperture Av and variable aperture manual modes. The shake reduction works by moving the sensor chip in response to twitches of the hand while shooting. This mechanism doubles up as a dust removal system by vibrating the sensor to shake off bits of dust. However, it couldn't shift a tiny hair which got in so I used the mirror-up-shutter open option and blew the hair out with a dust extractor.
Having mentioned that old Pentax K bayonet lenses can be retrofitted I should add that my old 1980's Pentax flashgun works with the camera too, thus saving even more cash. They said in the shop that it wouldn't and I said 'it will you know' and it does (although I have to add that I haven't tested all its functions yet). The camera's small built in flash is adequate; handy for fill in but with a limited range, as one might expect.
Power is provided by a rechargeable lithium-ion battery and the optional grip carries a second battery. I take a lot of long exposures (e.g. astronomy stuff) so I was unsurprised to run each battery flat with 300 exposures. Typically, they run to 450+ exposures. Battery health indicators are never really reliable but I know when the batteries are on their last few shots; the rear (aperture, etc.) selection dial on the camera stops working! (On my old Pentax DSLR the warning sign was rapid repeated firing of the shutter; ironically frenetic, given that the power was running out.)
Image quality has come up in several reviews. There is general agreement that the K10D takes excellent RAW images but there are mixed feelings about its JPEG images. The truth is that, like all sophisticated instruments, the camera simply needs calibrating, using the on-screen menu, before starting. Like earlier Pentax DSLR's this one is best adjusted away from the default values to slightly brighter, sharper and more saturated settings.
I also own an older Pentax *istD DSLR and can see the best of its features brought forward into this model while the worst have disappeared (e.g. the noisy shutter). The new camera is inevitably bigger and heavier but it is also better spec'd, faster and more versatile. Because I had a Pentax lens set, this camera was a no-brainer, but others should look at it too. It is not a beginner's camera but experienced users should seriously consider it (provided they don't need truly exotic types of lenses to fit to it) instead of being carried along by the Nikon/Canon bandwagon.