Autofocus
One of the criticisms often levelled at Pentax SLRs is that their autofocus system is slow and noisy. While the SAFOX VIII+ 11-point autofocus system in the K-7 is an improvement upon earlier versions, it struggles with less than perfect targets and the familiar ‘zzz-zzz’ sound of the motor is still present at these times.
In good light, AF adjustments are conducted quickly and surprisingly quietly, considering the noise produced when the lens hunts.
Although the nine cross-type AF points positioned around the centre of the imaging frame can usually be relied upon to find their target even in quite low light, in the very overcast conditions I experienced during some of this test the outer two linear AF points were almost useless. Further testing conducted once the firmware upgrade (V.1.01) was issued suggests that this has been significantly improved. The situation is also much better in brighter weather and with high-contrast subjects.
When set to continuous AF, I found that the K-7 does a reasonable job of keeping track of moving subjects provided one of the central cross-type AF points is selected and the target doesn’t move too quickly. Although it managed to keep up with children bouncing on a Bungee trampoline (elasticated ropes help them bounce higher and descend more slowly), it struggled with the faster, more random movements of swans at close quarters. I think the K-7 is unlikely to be the camera of choice for sports photographers, despite the 5.2fps maximum continuous shooting rate.
As we now expect with new DSLRs, the K-7 has both contrast and phase detection AF in its Live View mode. The contrast detection system is on a par with that used in most other DSLRs. Sharp focus is achieved, but not quickly enough to use it with moving subjects. There’s also a face detection option, which is good at recognising that there is a face in the scene but it’s slow to focus on it.
When set to its movie mode (via the main control dial), the K-7 can only focus automatically before the shutter release button is pressed to start recording. Once video shooting has been started, the focus can only be shifted manually using the lens focus ring. This is generally preferred by experienced videographers, but it may not be so popular with those who are more familiar with small, mass-market video cameras.
This shot, taken using the smc Pentax DFA Macro 50mm f/2.8 lens on the K-7 at ISO 400 and an aperture of f/2.8, has plenty of detail. However, the out-of-focus area bokeh looks rather unnatural, as there appear to be sharp halos or bands around some of the edges of this crocosmia flower
