The Pentax K-x follows the cheaper K-m in its use of AA batteries. This makes it unique compared to competitors - Sony, Canon, Nikon and Olympus all use rechargeable lithium-ion batteries in their DSLRs.
The use of AAs is a disadvantage out of the box. You get four non-rechargeable lithium batteries with the camera: according to Pentax that's enough for 640 shots, or 420 shots if you use the flash half the time.
That's reasonable - we took well over 270 shots plus videos in a single day and didn't run out of power. However, if you want to recharge the batteries you'll need to buy four Ni-MH AAs plus a charger - count on spending £20 on a complete set.
The use of AAs does have its advantages though. Firstly, Pentax claims that four rechargeable Ni-MH batteries will be enough for 1,100 shots with 50 per cent flash use, which far outstrips the Canon 500D's lithium-ion battery (400 shots) or the Nikon D5000's (510).
Secondly, if your proprietary lithium-ion battery dies in the middle of nowhere you're stuck until you can find somewhere to plug it in; AA batteries can be bought virtually everywhere on Earth.
The K-x's performance is typically DSLR-like. We measured its start-up time at 0.20 seconds, which unless you have the twitch muscles of a cheetah is much quicker than you could bring the camera to bear on a subject.
There's no shutter lag to speak of and unless you're in continuous shooting mode the time between shots is negligible too - in our tests we measured times as fast as 0.3 seconds between shots.
There are two continuous modes - Hi and Lo. Pentax claims the high mode should produce speeds of up to 4.7 frames per second if you keep your finger on the shutter button. We took 11 shots in 2.16 seconds, which is actually slightly faster - 5fps.
That's impressive for a mid-range camera. It's not so proficient at prolonged bursts - after around 17 shots speed slowed, and over the course of 11 seconds the K-x averaged 2.21fps. At its peak, though, the K-x is faster in continuous mode than either the Canon 500D or the Nikon D5000, although it only squeaks past the latter.