Zoom
Good performance from the Pentax K100D's 18-55mm kit lens.

18mm	55mm

The Pentax K100D is available bundled with the Pentax SMC-DA 18-55mm f/3.5-5.6 kit lens. The K100D works with a huge array of K-mount lenses. Results are good at wide angle, with a slight softness throughout the frame. Some coma distortion and chromatic aberration in the corners, as expected. The lens shows a good deal more detail at telephoto, and is fairly contrasty. This far field performance differs slightly from what you'll see below in the Corner Softness section, where the wide angle lens is sharper in the center and corners and softer at telephoto (which is precisely why we shoot a "far" shot, because lenses are often quite different focused near compared to far).

Macro
A small macro area with good detail. Flash performs well up close.

Standard Macro	Macro with Flash

As with zoom performance, the Pentax K100D's macro performance will depend on the lens in use. However, with the 18-55mm kit lens set to 55mm, the K100D captured a small minimum area measuring 2.58 x 1.72 inches (66 x 44 millimeters). Details are a little fuzzy throughout the frame, with some additional softness in the corners from the lens, but resolution is still good. There's a slight reddish color cast from the automatic white balance setting. The flash exposure looked pretty good, with nearly even coverage (though some slight falloff in the lower corners).

Distortion
Moderate barrel distortion, and slightly high pincushion.

This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide angle) or inward (like a pincushion -- usually at telephoto). The Pentax K100D's 18-55mm kit lens produced about 0.72% barrel distortion at wide angle, which is actually slightly less than average among the cameras we've tested, although still noticeable in its images. At the telephoto end, the lens produced about 0.15% pincushion distortion, which is slightly more than average.

Barrel distortion at 18mm is 0.72%

Pincushion at 55mm is less than 0.15%

Chromatic aberration
Moderate to very low distortion with the 18-55mm kit lens.

Wide: moderate but bright, top left @ 200%	Wide: bright, top right @ 200%
Tele: low, top left @200%	Tele: no visible pixels, top right @200%

Chromatic aberration with the Pentax K100D's kit lens is moderate at the 18mm setting, though fairly bright, showing about 5-6 pixels. At 55mm, the distortion is very slight in the top left corner, and virtually invisible in the top right. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.)

Corner Sharpness
Slight softening in the corners with the 18-55mm kit lens.

Wide: Slightly soft in the lower corners (lower left)	Wide: sharper at center, though still slightly soft
Tele: slightly soft in the corners (lower left)	Tele: still slightly soft at center

The Pentax K100D's 18-55mm kit lens produced slightly soft corners in a few shots. At wide angle, corners were a hint soft, particularly in the lower corners, compared to the center of the frame. At telephoto, corners showed stronger blurring, but the center was also a bit soft. Still, not a bad performance.

Coverage
A very accurate optical viewfinder.

18mm eq., optical viewfinder	55mm eq., optical viewfinder

The Pentax K100D's optical viewfinder proved reasonably accurate, showing about 99% accuracy at wide angle, and about 96% accuracy at telephoto. This is quite a bit better than most digital SLRs.