Pentax KP Review

Focusing

The Pentax KP uses three different autofocusing systems: phase detect autofocus (PDAF) for viewfinder shooting, contrast detect autofocus (CDAF) in live view, and hybrid autofocus for continuous focus adjustments during video.  On this page, we will discuss the former two methods which pertain to still photography.

Viewfinder Autofocus

In the viewfinder, the Pentax KP features the 27-point SAFOX 11 autofocus system originally launched in the Pentax K-3 II.  Both these cameras incorporate software tweaks that deliver improved tracking performance over other models.  This is currently the highest number of AF points in any Pentax APS-C camera; the only Pentax model with more points is the full frame K-1 with its 33 points.  It shows that at least as far as focusing does, the KP is as good as the flagship line, and is thus set apart from lower models such as the K-70.

There are 25 cross-type autofocus points laid out in a 5 x 5 grid in the center of the frame, along with two line sensors in the off to either side.  Three points in the center of the frame are extra-sensitive and can work with additional light from fast lenses.  Per the specifications, all the points are sensitive down to -3EV of ambient light.  What this means in practice is that the KP is excellent at focusing in low-light conditions, and will almost always be able to lock focus if the scene is just bright enough to be seen by the human eye.

Pentax KP viewfinder autofocus system

The low-light performance of the KP continues to be class-leading, and is only bested by far more expensive flagship cameras such as the Nikon D500, which focuses down to -4 EV.  On the other hand, the AF point density is a bit behind by modern standards, and the large gaps between the line sensors and the central grid take away from tracking performance.

As far as AF modes go, you can choose from 27-point automatic, 25-point automatic, 9-point automatic, or single point.  A SEL mode complements all three automatic modes, in which you select a single primary AF point but allow the camera to "expand" to other points as the subject moves.  This is excellent for tracking, as you can tell the camera where to initially focus while allowing it to leverage the point density to maintain focus on the subject.  We discussed each of these modes in more detail in our K-3 review (they are the same on the KP).

The viewfinder has an AF point overlay consisting of red LEDs.  This can be enabled or disabled via the menu.  Unlike on the K-1, which has a LCD overlay, only a single point is highlighted at a time on Pentax's APS-C models.  We do miss the fancier system found in the K-1, but it makes sense that it is currently only present on the highest K-mount model.

AF Tracking Test

Moving subject tracking during burst shooting is a good scenario for stress-testing a DSLR's focusing system.  To find out just how much the KP's tracking autofocus has been improved compared to the K-3 (and older bodies), and how well it fares overall, we performed a moving AF test similar to the one in our original K-3 review.  As shown in the illustration below, a bicyclist rode past the camera along a semicircular track, thus changing both his horizontal and vertical distance at any given time.

KP vs K-3 autofocus test setup (camera hand-held)

The camera was set to continuous-high mode with focus priority set.  We used two AF point modes: center-point and SEL-M (25 points).  Each test was repeated 3 times; the summed result is presented below.  We used the DA 18-135mm lens (set to 135mm) rather than the faster 55-300mm PLM in order to better expose any differences between the two cameras.

Our motivation for the AF mode selection was simple: center-point mode allows the camera to concentrate on focusing speed and accuracy alone, while the SEL-M mode shows us how well the camera can do both at the same time.

In-focus photo rate (sharp photos / total photos)

The results show that while both cameras sustained roughly the same framerate, the KP outperformed the K-3 handsomely regarding AF.  What's more impressive is that these cameras differ solely in software tweaks to the AF system.  The test also shows that the single point mode can provide a higher keeper rate than multi-point mode assuming it is feasible for the photographer to keep the selected point on the subject at all times.

Overall this shows that the KP is quite good for tracking, even without the fastest-focusing lens available.  However, there is certainly room for improvement— the utility of the fancy multi-point mode is questionable as its focusing speed and accuracy falls noticeably short of center point mode.  We previously performed this test with the Nikon D610 in 39-point tracking mode and captured 80 sharp photos, out of 82.  While the KP can compete with this figure in single point mode, the competition's multi-point tracking is still comfortably ahead.

Autofocus Fine Adjustments

All Pentax DSLRs since 2010 allow for fine AF adjustments to remedy front- or back-focus when shooting through the viewfinder, and the KP is no exception.  Learn more in our AF adjustment guide.

Live View Autofocus

Like the K-70 which debuted the system, the KP incorporates phase-detect autofocus pixels on the imaging chip.  These are not used in stills live view, however— only video.  Instead, a pure contrast detect system means that the KP functions just like other recent Pentax bodies such as the K-S2 or K-3.

In practice, the KP’s non-video live view AF is still quite good.  It is surprisingly fast given the lack of PDAF— with DC or PLM lenses, it is generally as fast as viewfinder focusing, assuming you have a stationary subject and plenty of light.

Multi-Point CDAF (identical on K-70)

The default focusing mode uses 15 focus points in a 5x3 grid, and it also allows for face detection within this region. If you switch to multi-point mode in the live view menu, the OK button can be used to adjust the size of the focusing area to 7x5 (the whole grid), 5x5, 3x3, or 1x1.  For best results we recommend using multi-point mode with a 5x3 grid.  This mode affords flexibility while minimizing mis-focusing on stray subjects.

AF locked in multi-point mode

One nice feature of the multi-point mode is that the camera does a fairly good job of predicting what you want to focus on. It can even outline your subject by covering it in AF points, as shown above.

AF in SEL mode

If multi-point mode gets it wrong, there is also a SEL mode that allows you to place a small AF area just about anywhere on the screen, as shown above. This mode enables the most precise focusing, but it is more time-consuming to use and the focusing speed will be considerably slower. We recommend this mode in scenarios where sharpness is critical, i.e. when shooting on a tripod.

In addition, the live view AF menu contains a spot focusing mode which is essentially SEL mode with the AF point centered, making it somewhat redundant. Also, if you stumble upon the tracking option in the menu, stay away—it simply does not work as one would expect (and is in our opinion of no practical use).

Manual Focusing Aids

While shooting through the viewfinder in manual focus mode, the KP offers AF confirmation. Catch-in-focus is also supported with manual lenses or any lens with an AF/MF switch.

When it comes to precision focusing, however, nothing beats live view. To this end, the KP features focus peaking and magnification. When enabled, focus peaking adds white outlines around objects that are in focus. Peaking can be enabled through the main menu or the control panel.

Standard Focus Peaking Off (Left) and On (Right)

The KP debuts a new, optional focus peaking mode called "extract edge".  In this mode, in-focus edges remain highlighted in while, but everything else in the scene is simply hidden and replaced by a flat grey color.

Extract Edge Focus Peaking

Customization is nice, and it's great that Pentax has finally started rolling out new focus peaking options.  However, since the subject itself can't be seen, the utility of this mode becomes situational.

The new focus peaking mode can be enabled through the Control Panel or main menu:

Outside of AF point selection mode, the OK button can be used to magnify the live view image up to the actual sensor resolution. Contrary to popular belief, this feature does not simply enlarge the small VGA image that's shown on the camera's monitor: it actually shows you exactly what the sensor sees. Zooming between 2x and 10x is possible, in increments of 2x. Best of all, magnification can be combined with focus peaking, which makes it perfect for manual focusing or fine-tuning the focus.

Live view magnification

There’s just one tweak we’d like to see made to this mode. Currently, if you engage the autofocus while the view is magnified, it will snap back to showing the standard live view image. It would be nice to keep the image enlarged to verify that the AF has done its job properly and to fine-tune it more easily. Currently, you have to zoom in manually every time after focusing.

Autofocus Speed

Assuming you're shooting in good light, the lens you choose has a much larger effect on focusing speed than the camera itself.  The fastest-focusing Pentax lens (by a large margin) is the DA 55-300mm F4.5-6.3 PLM.  With its new pulse motor, this lens focuses nearly instantly, many times faster than even the latest DC silent-focusing lenses.  It is thus an excellent choice for sports or any sort of action.

Screwdrive lenses with a short throw (such as DA Limiteds) are typically also very fast to focus, as are DC lenses such as the DA 18-135mm or DA 16-85mm with their rear-mounted focusing rings.  Slower-focusing lenses include screwdrive lenses with a long throw, such as the D FA 100mm macro or the DA 55-300mm F4-5.8, as well as DA* lenses with first-generation SDM silent AF.

If you are upgrading from the K-50 or older, you will notice much faster screwdrive AF speed, as the KP has a new generation screwdrive motor.

Everyday focusing speed is quite good for both viewfinder and live view shooting.  Gone are the days of hunting or slow live view AF, and only the most demanding action shooters will see the KP's AF performance as a shortcoming.

Verdict

Overall, the Pentax KP delivers excellent flagship-level autofocusing performance through the viewfinder, and it outperforms models that came before the K-3 II. The camera's solid low-light imaging quality is complemented by reliable low-light autofocus, which makes it a fine choice for shooting at night. Tracking performance is the only key area that could use improvement, though it has gotten quite a bit better over the years and will thus already satisfy all but the most demanding users.

Live view autofocusing is also quick, customizable, and user-friendly. We would still like to see more focus peaking choices, and of course the incorporation of hybrid AF into stills shooting to further speed up the focusing process and allow for effective shooting of moving subjects while in live view.

If you enjoy manual focusing, it's hard to go wrong with the combination of a tilting monitor and live view magnification plus focus peaking.  If you prefer to shoot through the viewfinder, the KP's catch-in-focus feature and focus confirmation can also make life easy.