Pentax K10D Exposure

Saturation & Hue Accuracy
Accurate color overall, though some oversaturation in some reds and greens. Generally good hue accuracy.

Most consumer digital cameras produce color that's more highly saturated (more intense) than found in the original subjects. This is simply because most people like their color a bit brighter than life. Like most pro DSLRs, the Pentax K10D renders colors much more accurately, showing almost dead-on hue and saturation, with only minor oversaturation of reds, greens and some blues.

Where oversaturation is most problematic is on Caucasian skin tones, as it's very easy for these "memory colors" to be seen as too bright, too pink, too yellow, etc. In this case, the K10D did produce slightly warm skin tones, but many consumers prefer the "healthier" appearance of warmer skin tones.

The other important part of color rendition is hue accuracy. Hue is "what color" the color is. The Pentax K10D often produced a slightly warm color balance, particularly with the Auto white balance setting. It also pushed yellow slightly toward green, and reds toward orange, but overall results were still quite good.

Exposure and White Balance

Indoors, incandescent lighting
Auto White Balance does not compensate for tungsten lighting at all. Good color with the Manual white balance setting, though just a hint warm. A little more positive exposure compensation required than usual.

Color balance indoors under incandescent lighting was pretty warm with the Auto white balance setting, though the Manual and Incandescent options both produced more accurate results. In the end, the Incandescent setting was just a hint too warm, though the Manual option was also on the warmer side. The Pentax K10D required a little more than the average amount of positive exposure compensation here, at +1.3 EV. Despite the slight warm cast, overall color with the Manual white balance setting is quite good, though the blue flowers appear very purple. (Many digital cameras have trouble here.) Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.

Outdoors, daylight
Bright colors overall, though a tendency toward a warm cast and high contrast under harsh lighting. About average exposure accuracy.

Outdoors, the Pentax K10D tended toward a warmer color balance, though overall color was generally pretty good. The K10D performed about average in terms of exposure, requiring the typical amount of positive compensation we're accustomed to seeing among consumer digital cameras. The K10D's default contrast is a little high, producing washed-out highlights and dark shadows under the deliberately harsh lighting of our "Sunlit" portrait test shown above left. The camera's contrast setting does tame the highlights and shadows slightly, but the overall effect is a slightly dimmer image.

See full set of test images with explanations
See thumbnails of all test and gallery images

Resolution
Very high resolution, 1,600 ~ 1,700 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,700 lines per picture height horizontally, and 1,600 lines per picture height vertically, with extinction past 2,000. Also note the mapping errors between the lines here, only on the vertical target at right; most disturbing is that they appear as colors, not just gaps or spots (see User Report on Overview tab for more). Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail. Our interpretation of this standard is somewhat conservative. We watch for artifacts and color fringing then move back to the nearest pure part of the scale. In our opinion, detail with artifacts shouldn't be considered detail. You may see other numbers quoted elsewhere, but across the site, our reviews judge this parameter by the same conservative standard.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Reasonably sharp images overall, though slight edge-enhancement on high-contrast subjects. Some noise suppression also visible in the shadows.

The Pentax K10D captures fairly sharp images overall, though some minor edge enhancement artifacts are visible on high-contrast subjects such as the crop above left. (Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.)

Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears. The crop above right shows some moderate noise suppression in the darkest areas of Marti's hair, though quite a few individual strands are visible in the lighter shadows.

ISO & Noise Performance
Low noise at the normal sensitivity settings, though a big jump in noise with strong blurring at the highest setting.

Noise levels are quite low at the Pentax K10D's lower sensitivity settings, with only moderately high noise at the ISO 800 setting. Noise increases at the 1,600 setting quite a bit, with much stronger blurring and increased chroma noise, though results are still quite good at such high sensitivity settings. Detail is reasonably usable even at 11x14 (see Output Quality section below).

Extremes: Sunlit and low light tests
High resolution with strong overall detail, but high contrast with strong highlights. Excellent low-light performance, capable of capturing bright images under average city street lighting and much darker conditions.

Sunlight:
Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here.)

The Pentax K10D produced high contrast with slightly washed-out highlights and deep shadows under the harsh lighting of the test above. However, shadow detail is pretty good, despite some noise suppression and bright-pixel image noise. Though some areas look a little hot at +1.3 EV, I preferred it to the image at +1.7 EV, which had too many blown highlights for my preference. (In "real life" though, be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible.) The camera's contrast adjustment does help tame the high contrast here, but overall results are just slightly dim.

Low light:
The Pentax K10D captured bright images down to the 1/16 foot-candle light level (about 1/16 as bright as average city street lighting at night), at all ISO settings. The camera's autofocus system was able to focus (albeit very slowly) on the subject down to just above the 1/16 foot-candle light level unassisted, which works out well for its exposure system. Do keep in mind though, that the very long shutter times necessary here absolutely demand the use of a tripod or other camera support to get sharp photos. (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)

NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) For such applications, you may have better luck with a digital SLR camera, but even there, you'll likely need to set the focus manually. For information and reviews on digital SLRs, refer to our SLR review index page.

Print Quality
Excellent print quality, great color, good 16x20 inch prints. ISO 1,600 images are soft but usable at 11x14.

Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon i9900 studio printer, and on the Canon iP5200 here in the office. (See the Canon i9900 review for details on that model.)

With the Pentax K10D, we were pleasantly surprised across the board. At 16x20, its ISO 100 prints were slightly soft, but quite good for wall or table display, retaining impressive detail in reds, where we're used to seeing oversaturation. ISO 400 shots were excellent at 13x19, with only some chroma noise in the shadows if you look very closely. ISO 800 shots stood up to 11x14 inch printing quite well. Though they were somewhat noisy, even our severe incandescent test produced usable images up to 11x14 at ISO 1,600, so long as we printed only the manual while balanced images (as we mention further up, the Auto White Balance's performance indoors with incandescent is the K10D's main shortcoming).

The K10D's printed results really impressed.