Quality & Size Options

The K-x supports four resolution settings. There are three available JPEG compression settings. In both RAW and RAW+JPEG modes, shooting is supported in Pentax’s PEF format or the DNG format created by Adobe. One of the many options for the programmable Green Button is switching temporarily to RAW+JPEG mode.

Dynamic Range (8.13)

The K-x performed well in our dynamic range testing, making it a good choice for handling high-contrast shooting situations without losing detail in the very bright or deeply shadowed areas. We test dynamic range by shooting a Kodak stepchart with 20 patches from solid white to solid black, with a range of gray values in between. Test photos are taken at each ISO level, across the full aperture range. These test images are then analyzed using Imatest software to determine how many distinct patches can be identified in each, then those results are compiled to create an overall picture of the camera’s performance.

The K-x delivers a 7-stop dynamic range at ISO 200, which is quite good, and retains nearly 5 stops out to ISO 1600. More on how we test dynamic range.

Comparing dynamic range for the cameras in our roundup at ISO 200, only the Canon T1i offered a wider dynamic range. After that, though, the T1i takes a steep dive, down to 4.27 stops at ISO 400, at which point the K-x still measures 6.21 stops.

Image Stabilization (2.02)

The K-x incorporates sensor-shift image stabilization in the body of the camera, so any attached lens reaps the benefits (versus Canon and Nikon SLRs, which use lens-based stabilization, with some lenses equipped with IS and others without). And there are benefits to be reaped here, in combatting up-and-down camera shake. When it comes to horizontal camera shake, on the other hand, the IS system was largely ineffective.

We test image stabilization by mounting the camera in a computer-controlled rig that produces programmed movement patterns at low shake levels (about what you’d find in a typical handheld shooting situation) and high shake levels (about the same as shooting one-handed, or while moving). We test at a variety of shutter speeds, moving the camera both horizontally and vertically, with image stabilization turned on and off. The thousands of test photos have their resolution levels analyzed using Imatest software, and the measured differences between results shot with and without IS lets us determine the system’s success. More on how we test image stabilization.

In our low-shake testing, we found the image stabilization system make very little difference when it comes to horizontal shake, but produced a worthwhile advantage when the camera bobbed up and down.

The same pattern holds true when we cranked up the level of shake, with a consistent and meaningful improvement.

The stabilization performance of the K-x is nearly identical to the K2000, which makes sense. The Canon T1i, with its lens-based stabilization, was by far the best of the bunch.

The table below provides representative same-size crops from our horizontal stabilization testing.

Image Stabilization Comparison Table			Expand
	Low Shake IS Off	Low Shake IS On	High Shake IS Off	High Shake IS On
1/500
1/250
1/125
1/60
1/30
1/15
1/8