Autofocus
One slight niggle with the Pentax K-7 was the slow and noisy AF. The K-5 features a revised Safox IX+ AF system, which maintains the 11 selectable AF points, nine of which are cross-type. The main difference with the new system is that the 11 AF points are spread wider over the frame. The AF uses a dedicated AF assist lamp, which helps in low-contrast light.
Although the AF is still characterised by its noisy motor when it hunts for a focus subject in low-contrast light, the revised Safox IX+ is an improvement on its predecessor. I found it generally responsive and accurate, even in low-contrast light, and the situations in which it struggles to lock onto a subject are less frequent.
As the K-5 offers a shooting rate of 7fps, it may be of interest to action photographers. This makes the autofocus particularly important.
I spent a couple of hours photographing people snowboarding and sledging (and an overexcited dog running) down a hill during the snowy week using continuous AF mode. The K-5 is good at tracking moving subjects, especially if one is in the centre of the frame. Also, as the 11 AF points are set wider over the frame, the Safox IX+ has a larger and more forgiving focus area. The AF will struggle if the subject slips out of the focus area, and the two non-cross-type AF points on the edges of the AF area are of little help.
Although the AF system is quick in low-contrast light for single-frame shooting, in low light and crowded scenes the continuous AF takes longer to find a focused subject. This affects the frame rate.
In raw mode, seven frame per second shooting is available for one second
I took the K-5 to a floodlit football training session and in continuous AF with focus priority setting I could often only achieve two or three frames at a time. In the custom menu you can change the priority to frame rate, but the continual control over focus is compromised.As in the K-7, only manual focus can be used in the K-5 once recording has been started in video mode when the initial auto focus has been made.
