Pentax K-30 Review
Now, let's take a look at one of the areas which Pentax claims to have improved the most in the K-30: its autofocus.
Phase Detect (Traditional)
The implementation of phase detect AF (PDAF) on the K-30 will be instantaneously familiar to anyone who's used a Pentax dSLR before (or, indeed, anyone who's used any dSLR before). There are three autofocus drive modes: AF.S (Single), AF.C (Continuous), and AF.A (which lets the camera decide whether to use AF.S or AF.C). Within these drive modes, there are four autofocus area modes: Auto 11, Auto 5, Spot, and Select. As this suggests, the K-30's PDAF system has 11 total AF points, nine of which are "cross-type" (the more desirable kind).
Auto 11 mode: This option uses all 11 AF points, and the camera takes a swing at figuring out what you want to focus on, using a very complex set of algorithms that prioritize different types of subjects. Most newbies will gravitate to this setting or the Auto 5 setting, because it's how most point & shoot cameras focus. We suggest moving away from this mode as quickly as possible, since it gives you very little control over what you're getting in focus.
Auto 5 mode: See above, just uses fewer points.
Spot mode: Uses only the center AF point. When this mode is selected, focus tends to be very precise, and you definitely always know which part of the frame will end up in focus. However, quality framing often requires the user to focus and then recompose, which might affect the final focus on the subject due to movement of the focal plane (especially at wider apertures).
Select mode: Also uses only one point, but lets you choose which one. We use this mode almost all the time, since it provides great accuracy and lets us frame our shots creatively without having to focus and recompose. When this mode is selected, the user can press the OK button to switch the d-pad buttons between controlling their secondary functions and controlling the focus point. The selected focus point is shown on the LCD and lights up red in the viewfinder.
Last but not least, PDAF has one more trick up its sleeve: Expanded Area AF, an option buried in the AF Settings submenu of the Record menu. To use Expanded Area AF, you must turn it on in the AF Settings submenu, set the AF drive mode to AF.C or AF.A, and use Select for the AF area mode. With these requirements met, the camera will let you choose a focus point as you normally would in Select mode. When you do so, the points immediately surrounding it will light up in pink on the LCD. If you then focus on a subject using your chosen point and it subsequently moves, the AF system will attempt to track your subject throughout all of the highlighted AF points. In other words, this is your best bet for trying to shoot birds in flight, dogs running across fields, and so on.
Contrast Detect (Live View)
When shooting using the LCD, the K-30 offers four autofocus modes: Spot, Select, Face Detect, and Tracking. You can select the AF mode from within the Record menu, or through the INFO screen. Each mode makes use of one or more of the K-30's 100 CDAF focus areas, which cover all but the extreme edges of the frame. Note that these areas aren't physical sensors as in a PDAF system; they simply represent a section of the frame as recognized by the camera's CDAF algorithm.
Spot mode: The camera uses the four central focus points to focus on what's at the middle of the frame. This is a good mode to use if you like to focus and recompose, but most will find Select mode to be more useful, as you can set it up to work like Spot mode but can also adapt it to other purposes.
Select mode: Allows the user to select any group of either 4, 16. or 36 AF areas from the 100 total on the screen. Pressing OK while in Live View brings up the grid of 100 areas; you turn the rear e-dial to change the size of the selection area and use the d-pad to move it around the screen.
Face detect mode: The camera activates the central 36 AF areas and tries to find a face in this zone. If it locks on to a face, it will use all 100 points to track it. This is the default mode, but we strongly recommend that people move on to Select mode except in cases when they're shooting portraits.
Tracking mode: In this mode, the user focuses on their chosen subject and the camera tries desperately to keep it in focus. Typically, it doesn't work so well. The camera loses track of the subject easily, and reacts slowly to changes in the scene's composition. It's important to note that this mode essentially tries to keep a single, static point in the frame in focus as the camera itself moves; it will not track a moving object.
Focus Peaking and Zooming, and Manual Focus
Another feature that the K-30 has inherited from the K-01 is focus peaking, which outlines high-contrast edges in the frame that are currently in focus. It's an easy way to tell if you've focused correctly, since you just have to look for the white halo around your subject. Focus peaking is only available in Live View shooting, for obvious reasons. Less obvious is why focus peaking is not available in movie mode. But maybe we'll see it in a firmware update.
Manually focusing with fast lenses is made much easier by the inclusion focus peaking, but it's not a cure-all. The area that gets highlighted by peaking is actually quite large when you're working with fast glass, and you need to sort of target the "center," or most intensely shaded part of the highlighted area to get exact focus when using a f/1.4 or f/1.2 lens. Sony's focus peaking feature offers more finely tuned control, and we hope to see Pentax work on something similar in future attempts.
Focus zooming (Autozoom) is available in AF mode. This feature enlarges the central focal point area after the camera has locked focus, so that you can be sure your subject is in focus. Autozoom activates about one second after focus is achieved, giving you a moment to assess your framing before it zooms in.
Autofocus (and Shutter) Noise
The action of the K-30's focusing system sounds pretty much like what you'd get from any other Pentax dSLR. The pitch and volume varies a little bit depending on the lens currently mounted (a shorter focus throw and a lighter-weight lens typically means a faster, higher-pitched focusing sound), but they all whine and they're all fairly loud, at least relative to Nikon's SWM, Canon's USM, or even Pentax's own SDM and DC lenses.
The shutter sound is, to our ears, very similar to the K-r's—perhaps a little quieter. It's not as quiet as the K-5's, nor quite as loud as the K-x's. Pretty much run of the mill for a Pentax camera.
You can get a quick sample of both in the video below, phase detect autofocus first, then contrast detect.