Pentax K-x Review

by Jeff Keller, DCRP Founder/Editor

Originally Posted: March 5, 2010

Last Updated: February 13, 2011

The Pentax K-x (from $649) is an entry-level digital SLR that doesn't skimp on features. It features a 12.4 Megapixel CMOS sensor, a compact, well designed body, full manual controls (plus an auto scene recognition mode), fast continuous shooting, live view, 720p video recording, and more. And, unlike most D-SLRs, the K-x uses AA batteries (and gets great battery life, to boot).

The K-x has some tough competitors, including the Canon EOS Rebel XS, Nikon D5000, Olympus E-620, Panasonic Lumix DMC-G1, Samsung NX10 (coming soon) and the Sony Alpha DSLR-A380. How does it fare against those cameras? Find out now in our review!

What's in the Box?

The K-x is sold in a variety of kits and colors, though you won't find a body-only kit. The camera and 18 - 55 mm lens kit ($649) comes in black, white, navy blue, and a red that will certainly get you noticed. If you want more than one lens, it'll be black only. The dual lens kits include the 18-55 and either a 50-200 ($749) or 55-300 ($849) lens in addition. Here's what you'll find in the box for each of those:

  • The 12.4 effective Megapixel Pentax K-x camera body
  • F3.5-5.6, 18 - 55 mm Pentax D-AL lens
  • F4.0-5.6, 50 - 200 mm Pentax D-AL lens [50-200 kit only]
  • F4.0-5.8, 55 - 300 mm Pentax DA lens [55-300 kit only]
  • Four AA lithium batteries
  • Body cap
  • Shoulder strap
  • USB cable
  • CD-ROM featuring Pentax Digital Camera Utility 4
  • 315 page manual (printed)

Whichever kit you buy, it includes a lens, so you can start taking pictures right away. The main kit lens is a lower cost version of the F3.5-5.6, 18 - 55 mm lens that's been around for a while. Pentax swapped the metal lens mount on the retail lens (which also version 2, this one is version 1) with a plastic one here, to keep costs down. While not spectacular, it's a decent kit lens, with good sharpness (though it falls off toward the sides of the frame), relatively little barrel distortion, and (usually) low levels of purple fringing. If you want to use another Pentax lens, there are plenty to choose from, whether they're brand new or decades old (though old lenses may require an adapter). Whichever lens you use, you'll have a 1.5X focal length conversion factor to keep in the back of your mind.

As with all D-SLRs, Pentax does not include a memory card in the box with the K-x. So, unless you already have one, you're going to need to pick up an SD or SDHC memory card right away. I'd recommend a 2GB or 4GB card to start with, and it's worth getting a card rated as "Class 4" or higher for best performance.

The K-x is one of very few digital SLRs that use AA batteries for power. I, for one, happen to like this, as they're cheaper than their proprietary counterparts, and you can easily get them in an emergency. I'd recommend picking up a set or two of NiMH rechargeable batteries (2500 mAh or higher) which will save you money in the long run (and help the environment while you're at it). Here's what kind of battery life you can expect from the K-x and its competitors:

Camera Battery life, live view off
(CIPA standard)
Battery used
Canon EOS Rebel XS 500 shots LP-E5
Nikon D3000 510 shots EN-EL9a
Olympus E-620 500 shots BLS-1
Panasonic Lumix DMC-G1 * 330 shots DMW-BLB13
Pentax K-x 420 shots 4 x 1900 mAh NiMH
Samsung NX10 * 400 shots BP1310
Sony Alpha DSLR-A380 510 shots NP-FH50

Battery life numbers are provided by the manufacturer

* Live view only

Pentax isn't doing themselves any favors by testing the camera with anemic 1900 mAh batteries! I figure that you can take at least 550 shots per charge using more powerful 2500 mAh batteries. At that point, the K-x beats all of its competitors. If you use non-rechargeable lithium batteries, you can take a whopping 1100 shots per charge. While you can use alkalines, you can only take around 130 shots per charge.

Pentax doesn't publish live view battery life numbers for the K-x, but it's safe to say that it's at least half of what you see above.

Pentax does not offer a battery grip for the K-x.

Being a digital SLR, you shouldn't be surprised to hear that there are plenty of accessories available for the K-x. Here are the most interesting ones:

Accessory Model # Price * Description
Lenses Varies Varies The K-x supports all Pentax K-mount lenses with a 1.5X focal length conversion ratio
External flash AF200FG
From $112
From $235
First one is pretty basic (doesn't bounce) and has a GN of 20. The other two are more powerful, can bounce, and support high speed sync and wireless.
Auto macro flash AF160FC From $439 Ring flash for close-up photography
Off-camera shoe adapter Shoe Adapter F $25 Gives you a flash sync port and keeps the hot shoe available
Wireless remote control Remote control F From $24 Another way to take photos without touching the camera
A/V cable I-AVC7 $10 Since Pentax doesn't include one, you'll need to buy this to connect the camera to a TV
AC adapter K-AC84 $65 Power the camera without draining your battery
* Prices were accurate at time of publication

Notice how the A/V cable is included in that table -- Pentax doesn't include one in the box, I guess to keep the price of the camera down. There are a couple of other things available, including various viewfinder accessories and camera cases.

Pentax Digital Camera Utility 4 for Mac

Pentax includes a single software product with the K-x, and that's their Digital Camera Utility version 4. This software -- for Mac and Windows -- is based on SilkyPix, which is often bundled with many other RAW-capable cameras. Thankfully, the interface in the Pentax Utility is a lot cleaner than in regular SilkyPix, though it's a bit sluggish at times.

This software can be used in a few ways: for acquiring images from your camera, for managing them in a lightbox-style interface, and for performing some pretty heavy-duty edits (for RAW images, specifically). The editing tools are quite powerful, and can be used for both JPEG and RAW images. Here are some of the things that you can do:

  • Crop, rotate and "shift" an image
  • Change the Custom Image setting (more on this later)
  • Adjust and fine-tune white balance
  • Adjust exposure and image tone
  • Select amount and type of noise reduction applied
  • Correction for distortion and chromatic aberration
  • Adjust coloring of highlight areas
  • Expand dynamic range
  • Fine-tune color in a given range

In other words, this software covers just about anything you can possibility imagine. I should also add that Pentax Utility supports batch processing, and the whole user interface is quite customizable.

If you want to use Photoshop CS4 or a recent version of Photoshop Elements to work with the K-x's RAW files, you'll just need version 5.6 or newer of the Camera Raw plug-in.

What's the deal with RAW images anyway? These files contain unprocessed data straight from the camera's sensor. The benefit of this is that you can tweak many camera settings (white balance, exposure, color) without reducing the quality of the image. It's almost like getting a second chance to take a photo. The downsides are the need to post-process the images on your computer, and the huge file sizes, which reduce camera performance and quickly fill up your memory card. The K-x is somewhat unique in that it supports two RAW formats. You can use Pentax's own PEF format, or Adobe's open standard known as DNG (digital negative).

While it's not perfect, the manual that comes with the K-x is definitely better than average. It's thick, detailed, and has good explanations of everything, without too much fine print. As for documentation for the Pentax Digital Camera Utility software: it'll be installed onto your computer.