Pentax K-x review
The biggest improvement in the AF is that the AF points can now be selected individually. However, the AF point in use is not illuminated in the viewfinder, which can make it difficult to remember which point is in use and where it is placed in relation to the subject on which you are trying to focus.
On the whole, the AF system of the K-x seems slightly faster than the AF of the K-m. I found that the K-x still searches for focus a little too much when in AF-C mode and it isn’t as ‘snappy’ as more expensive cameras.
That said, unless you intend to photograph sports or fast-moving wildlife, the AF should be able to cope adequately with most situations.