Pentax K2000 Digital Camera Review - Pentax DSLR

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	Resolution Summary
• Maximum resolution 10.2 megapixels • Surprisingly high scores for all three aspects of our testing with inexpensive kit lens • Inconsequential chromatic aberration and distortion • Sharpness impressive at most settings, falls off at very small apertures • Dynamic range comparable to higher-priced SLRs • Image stabilization helpful only at slow shutter speeds
	Noise	Page 5 of 18	White Balance

Resolution (10.28)

The Pentax K2000 delivers 10.2-megapixel resolution, a fairly modest figure by today's SLR standards. What we're most concerned about, though, isn't the number of dots but the bottom-line quality of the photo taken, which combines the effects of the image sensor itself, the lens optics and the image processing that takes place. In this testing, the K2000 did exceptionally well, especially for a $600 camera with a kit lens. We found very little distortion, minimal chromatic aberration and image sharpness with many strengths and only a few trouble spots.

We test the three aspects of overall resolution performance mentioned above, but based the scoring for SLRs on only chromatic aberration and sharpness, since the distortion performance will vary widely depending on the lens used. Shooting is done under bright studio lighting at three focal lengths (maximum, minimum and midpoint), and at three aperture settings for each focal length (again, the largest, smallest and the one in the middle). For details on our resolution testing process, see the How We Test section here.

Distortion
Overall the Pentax K2000 performed very well in our distortion tests. The only significant problem occurred at the 18mm focal length, where we found an average barrel distortion of 2.08%. Moving out to 35mm there was only a trace amount of pincusion distortion, at 0.48%. And at the maximium focal length, pincushion distortion rose to 0.90%, still a very impressive performance from the kit lens on an inexpensive camera.

Chromatic Aberration (8.02)
Here again, the Pentax K2000 more than held its own. achieving a higher score for chromatic aberration than the Sony A900 we tested using a 24-105mm lens that costs as much as the entire K2000 kit. As seen in the images below, the most notable flaws occurred at the 18mm focal length, where there is significant horizontal chromatic aberration from the midpoint to the edges of the image. This flaw largely corrected itself by the time we zoomed out to 35mm, to the point where it wouldn't cause visible problems even at substantial magnification. With this single exception, chromatic aberration is well controlled across the lens.

Sharpness (11.25)
We found the sweet spot for the 18-55mm kit lens when shooting at the 35mm focal length at f/11, where the lens delivered 1638 lw/ph horizontally and 2098 vertically.

In the charts below, we show actual-size crops taken from the test chart photos at each focal length. As you can see, at 18mm, there's some noticeable chromatic aberration at the edges of the image, and the image softens noticeably across the board when the lens is stopped down to f/22, but the center is tack-sharp until that point.

	Image Sharpness
	f/3.5	f/9.0	f/22

18mm

Shooting at 35mm, chromatic aberration is less of a problem, even at the extremes, and the center looks even better than the already solid results taken at the wide angle setting above. Only the f/32 shots show noticeable softness.

	Image Sharpness
	f/4.5	f/11	f/32

35mm

The pattern holds at 55mm, where stopping down to f/40 results in significantly fuzzy edges, but chromatic aberration is negligible and the images shot at f/5.6 and f/16 look nice and crisp from corner to corner.

	Image Sharpness
	f/5.6	f/16	f/40

55mm

When compared to the other cameras in our test group, the Pentax holds a significant advantage over the Canon Rebel XS in the same price range, and does well in a head-to-head comparison with the $1000 Nikon D90. The Olympus E-30 is again the outlier in the group, lowest in image noise by a hefty margin but posting superb resolution scores.

Resolution Score Comparison

Picture Quality & Size Options (8.65)

The number of available file sizes is limited to just three:

Image Size Options
10 megapixels	3872 x 2592
6 megapixels	3008 x 2000
2 megapixels	1824 x 1216

There are three JPEG quality settings, Best, Better and Good. When shooting uncompressed RAW files there is a choice of two file formats, Pentax's own PEF files or the standard DNG RAW file format. RAW images can be saved on their own, or with a simultaneous JPEG copy.

Dynamic Range (8.62)

The Pentax 2000 performed well in our dynamic range testing. Four out of five cameras in our comparison suite scored within a hair's breadth of one another in this test and, while the Pentax was statistically the lowest of these four, the difference is inconsequential in real-world effect.

Our tests for dynamic range are conducted by shooting a standard 20-patch Kodak Gray Scale chart under controlled 3000-lux illumination, shooting at each available ISO at a range of aperture settings. The resulting images are analyzed using Imatest software to determine how well the tested camera can maintain detail in dark areas and reproduce highlights without blowing them out. For further details about our dynamic range testing process, read the How We Test section here.

Dynamic Range

Dynamic range inevitably decreases as ISO settings increase, but for the K2000 the effect is smooth and gradual. The camera starts out at ISO 100 with over seven stops of dynamic range, barely dips below 6 stops at ISO 400 and still produces a respectable result into the noisy realm of ISO 3200 shooting.

Dynamic Range Comparison

The chart above shows the relative dynamic range results for our five comparison cameras shooting at ISO 200. Aside from the Olympus, the others all display very similar dynamic range performance here.

The Olympus had noise problems across the board, and at extreme ISOs produced photos which were simply unusable, which explains its poor performance. The scores each camera received in each section are shown below; a longer bar indicates a higher score.

Dynamic Range Score Comparison

Image Stabilization (4.64)

The Pentax K2000, like Olympus and Sony SLRs, has image stabilization built in to the body of the camera. This contrasts with the approach taken by Nikon and Canon, who build image stabilization into individual lenses, which are more expensive than similar lenses without stabilization. The benefit of the Pentax approach is that any lens you mount on the camera can take advantage of image stabilization... when there is an advantage. In our lab testing, we discovered that the Pentax system offers modest improvement where it counts the most, when shooting at shutter speeds of 1/30 second or lower. At higher shutter speeds, though, the results are hit-and-miss. In many instances, engaging the image stabilization system produced blurrier photos than turning it off.

Our image stabilization testing is conducted using a custom-made rig that precisely shakes the camera in a pre-determined pattern, under computer control. With the test subject mounted in the device, we shoot at two different levels of shake, taking multiple images at all shutter speeds between 1/500 and 1/8 second. Horizontal and vertical shake are tested separately. The resulting photos are processed using Imatest to determine image sharpness, and these results statistically analzyed to determine the effectiveness of the image stabilization system. For details on our image stabilization testing process, see the How We Test section here.

When subjected to a modest level of shake -- roughly what we'd expect from an individual when holding the camera steady with two hands -- we found that horizontal shake improvement was negligible at shutter speeds below 1/30 second. In the vertical direction, image stabilization offered an improvement at the fastest 1/500 second speed tested, but caused a loss of sharpness for the remaining range until we reach 1/15 second, where some advantage kicks in.

Pentax K2000 Image Stabilization: Low Shake
Horizontal: Sharpness Vs Shutter Speed	Vertical: Sharpness Vs Shutter Speed
Horizontal: Sharpness improvement with IS on	Vertical: Sharpness improvement with IS on

The second phase of our test increases the level of shake until it represents what you'd experience when trying to grab a shot one-handed, or when walking. Here we see a similar pattern to our low-shake test. At the highest shutter speed the sharpness is better with image stabilization turned on, but from that point on it's causing a dip in image quality until we get to the 1/30 second level.

Pentax K2000 Image Stabilization: High Shake
Horizontal: Sharpness Vs Shutter Speed	Vertical: Sharpness Vs Shutter Speed
Horizontal: Sharpness improvement with IS on	Vertical: Sharpness improvement with IS on

Bottom line, the Pentax K2000 image stabilization system is consistently inconsistent: that is, it sometimes improves sharpness, sometimes detracts from it, but in roughly the same pattern whether you are fairly steady or moving around quite a bit, and on both the horizontal and vertical axes. Our recommendation: turn the system on if you're shooting indoors without flash or at night, but leave it off otherwise.

The following table shows actual-size crops from photos taken for testing, chosen to demonstrate the relative effect of the image stabilization system at different shutter speeds and shake levels.