Camera Test: Pentax K-x | Popular Photography

Camera Test: Pentax K-x

This DSLR delivers HD video, live view, and ISO 6400 at a great price.


When knowledgable (and thrifty) photographers want a good deal on a budget SLR, Pentax has been the go-to brand for decades. To this day, you can still fi nd young photography students shooting with Pentax K1000 fi lm SLRs.

Does the company’s current entry-level DSLR, the 12.4MP K-x ($537, street, with 18–55mm f/3.5–5.6 lens), live up to the Pentax legacy? It sure does.

In features and performance, the little K-x stood up very well against its major competitors from Canon and Nikon. Starting with Pop Photo Lab tests, the K-x served up a Very High rating in overall image quality thanks to a Very High resolution score of 2125. That puts it on par with Canon’s 10.1MP EOS Rebel XS ($570, street, with 18–55mm f/3.5–5.6 IS lens) and Nikon’s 10.2MP D3000 ($550, street, with 18–55mm f/3.5–5.6 VR lens), which scored 2150 lines and 2100 lines, respectively. Like its two rivals, the K-x earned an Excellent Color Accuracy rating, again scoring in between them, with differences in results of the three so close as to be insignificant.

Noise, Autofocus, Speed

Noise suppression wasn’t terribly impressive at the lower end of its ISO range (both the Canon and Nikon beat it through ISO 400).

But at its highest ISOs, the K-x shined: At ISO 800 through 1600 (the Canon’s highest sensitivity), the Pentax edged ahead of the Nikon. While they both got Unacceptable ratings at ISO 3200, the Pentax showed significantly less noise (3.2) than the Nikon (5.5). And at ISO 6400—a sensitivity the Nikon doesn’t reach—it still did better than the D3000 did at ISO 3200.

The K-x’s autofocus tested well, too, with very strong performance in brighter light. At EV 12 through EV 6, it was equal to or faster than the two competitors. Though its AF was slower than the Canon and Nikon in dimmer light, it remained within 0.6 seconds of them even at its worst.

The K-x’s 11-point AF system offers a real improvement over the five-point system found in its predecessor, the K2000. It focused about 0.4 sec faster on average in the light levels below EV 4 in our lab tests. Plus, nine of the K-x’s AF sensors are cross-types concentrated in the center portion of the frame, for better sensitivity in both the horizontal and vertical planes.

Burst shooters will be glad that the K-x can capture up to 17 fullsize, highest-quality JPEGs at a rapid 4.7 frames per second. That makes it the fastest DSLR in this class, though not the most prolific burster. Canon’s Rebel XS can rack up 514 Large Fine JPEGs, albeit at a significantly slower 3 fps.

Ergonomics and Controls

One of Pentax’s strengths is body design, and the K-x is no exception. The grip includes a nice divot for your middle finger, and angles slightly inward to accommodate the fleshy part of your fingertips. Like those on most DSLRs in this class, the grip isn’t all that tall, so, depending on the size of your hands, you may find your pinky dangling below it while shooting. Around back there’s a clearly defined rest for your thumb, and a little bit of a ridge that provides leverage when angling the camera.

As is typical with entry-level DSLRs, there aren’t a lot of buttons dedicated to camera controls, and there's only one command wheel. Exposure compensation does get its own button, though, and it’s well placed next to the shutter release. During full manual shooting, you hold it down to change aperture.

We were happy to see that Live View also has its own button, but not so happy that the camera’s sensor-shift image stabilization didn’t get its own switch. You’ll have to jump into the on-screen controls to turn it on or off.

In our lab tests the IS system delivered an average of 1.5 stops of shutter-speed leeway when used with Pentax’s large 60–250mm f/4 lens zoomed all the way out. In practical terms, this means that if you normally have to use a shutter speed of 1/250 sec for sharp images while shooting handheld, you should be able to get similar results at 1/90 sec in identical conditions when IS is engaged. And, since the stabilization system is built into the camera body (unlike the Canon and Nikon lens-based systems), it will work with any lens you put on the body, even hand-me-down glass from Grandpop.

The info button on the back of the camera not only toggles through various configurations of on-screen information during playback, but also provides access to the K-x’s control panel, letting you change the most common functions quickly.

Looking for video? The K-x is one of the least-expensive DSLRs to offer HD capture. Sure, it’s 720p at 24 fps, not full 1080i at 30 fps, but at this price who can complain? The image quality of the Motion JPEG AVI footage we shot was on par with what you can expect from most DSLRs.

You can still find better image quality and a much simpler shooting experience with a camcorder, but if you’re comfortable with manual focus or don’t mind planning your shots to eliminate the need to refocus during a scene, then you’ll probably enjoy the footage you get from the K-x.

The Bottom Line

If you’re looking for a very inexpensive DSLR, you’re likely to be happy with the Pentax K-x.

Since nearly all the lenses Pentax has ever made will fit on any of its DSLRs, the frugal among us can find excellent older ones at used-equipment outlets and on eBay. Of course, some of these, such as the decades-old screw-mount lenses and medium- format lenses, require adapters to fit a modern body and have limited automatic functionality.

Prefer new optics? You’ll find some great ones, such as Pentax’s 100mm f/2.8 WR macro we tested this month.. And the superb Limited series of lenses is one of the most enjoyable sets of primes we’ve used.

Test Results

Imaging: 12.4MP effective, APS-C sized CMOS sensor captures images at 4288x2848 pixels with 12 bits/color in RAW mode.

Sorage: SD/SDHC stores JPEG, PEF or DNGRAW, and RAW + JPEG files.

Burst Rate: Full-sized JPegs (Fine mode), up to 17 shots at 4.7 fps using a SanDisk extreme SDHC card; PEF RaW; up to 5 shots at 4.7 fps.

AF System: TTL phase detection with 11 illuminated focus points (9 cross-type); single shot, continuous, or auto-select. Tested sensitivity down to EV –1 (at ISO 100, f/1.4).

Live View: Contrastdetection autofocus.

Shutter Speeds: 1/6000 to 30 sec (1/3- or 1/2-eV increments); not rated.

Metering: 16-segment TTL metering, evaluative, centerweighted, and spot (percentage of viewfinder not available), EV 1–21.5 at (ISO 200).

ISO Range: ISO 200–6400 (1/3-, 1/2-, or 1-EV increments).

Flash: Built-in pop-up with P-TTL autoflash and wireless triggering of optional flash units, gn 53 (ISO 200, feet); flash sync to 1/180 sec; dedicated Pentax hot-shoe.

Viewfinder: Fixed eye-level penta-mirror. LCD: 2.7-in. TFT with 230,000-dot resolution.

Output: Hi-speed USB 2.0/composite video.

Battery: 4 AA, CIPA rating 1,100 shots with one set of lithium batteries.

Size/weight: 4.8X3.6X2.7 in., 1.3 lb with an SD card and batteries.

Street Price: $537, with 18–55mm f/3.5–5.6 DA lens; $625 with 18–55mm and 50–200mm f/4–5.6 ED lens.