Camera Test: Pentax K20D

With rich features, a big 14.6MP sensor, and an estimated street price of $1,299, Pentax's super DSLR is a rare talent.

Camera-Test-Pentax-K20D

Camera-Test-Pentax-K20D

The 10.2MP Pentax K10D was a DSLR bargain in 2007 with its nearly pro body, excellent image quality, fast AF, image stabilization, and a price of only $920 (body only) when launched. It's still a steal at $700 (street). But if you want a camera with higher resolution, larger LCD, live view, and other enhancements, check out the new 14.6MP Pentax K20D ($1,299, estimated street).

At first, the K20D seems to be a twin to the K10D. Pentax kept what was outstanding in the K10D and improved it in all the right places, so the K20D is more of an upgrade than a new design. We got our hands on one of the first production units, and after running it through the Pop Photo Lab and field tests, found five reasons why this camera promises to be a big hit.

IMAGE QUALITY

This camera captures the most detail in its price class at ISOs below 1600. Incorporating the first Samsung-produced APS-C-sized CMOS sensor, the K20D represents a shift from the Sony CCDs found in previous Pentax DSLRs, and a further strengthening of Samsung's partnership with Pentax. By the time you read this, Samsung will have released its own camera with specs similar to the K20D.

According to Pentax, the new sensor captures 14.6 megapixels (effective) in 4672x3120-pixel files, with up to 12 bits per color in RAW. In addition, the pixel design expands the light-gathering photo diode to about the same area as competitive 12-megapixel CCD sensors. This gives the K20D the potential for higher resolution than the K10D, with light sensitivity similar to more expensive 12MP DSLRs such as the Nikon D300 ($1,800, street, body only) or Sony Alpha 700 ($1,350, street, body only). With increased sensitivity and noise reduction, Pentax boosted the normal ISO range up to ISO 3200, and the expanded range as high as ISO 6400.

The camera's PRIME image processing system can store RAW data from the sensor as JPEGs, PEF RAW (Pentax), RAW DNG (Adobe standard), or JPEG + RAW files. Or it can channel images to a live preview on the 2.7-inch LCD. And thanks to the lower power drain of a CMOS sensor, the rechargeable lithium ion battery (same as in the K10D) earns a CIPA rating of 720 shots (half with flash), despite more intensive processing (though it doesn't include IS battery drain).

Impressive specs? Yes, but the K20D produced impressive results in the Pop Photo Lab, especially in resolution and detail at most ISOs. At 2350 lines of resolution at ISO 100-400, the K20D delivers slightly higher resolution than the Nikon D300. Then resolution drops by 5-10 percent as you crank up noise reduction at higher ISOs. Nonetheless, at ISO 6400, the resolution was still Excellent at 2100 lines.

In noise or color accuracy tests, however, the K20D doesn't outclass the Nikon D300, especially at ISO 3200 and 6400, or when shooting JPEGs at any ISO. At ISO 1600 it earns a Moderate noise rating, but thanks to its high resolution and Excellent color accuracy at that ISO, it still qualifies for an Excellent image quality rating from ISO 100 to ISO 1600 when shooting RAW files and converting them to TIFF. At ISO 3200, noise levels are Unacceptable, and downright irritating at ISO 6400.

JPEGs earn just Extremely High ratings for image quality even at lower ISOs due to their less-than-stellar color accuracy, which comes in only at a High rating (11 average Delta E). That's two levels down from the Excellent color accuracy (7.98 Delta E) we found when making TIFFs with the supplied Pentax RAW converter (from SilkyPix, the same folks providing Panasonic's RAW converter). JPEG resolution is about 5 percent lower than RAW, but noise levels are similar even when converting RAW files in-camera and saving them as JPEGs (a useful feature).

The K20D turns out impressive images at ISO 100-1600, and proves that Samsung's new, larger DSLR sensors can stand up to the chips made by Canon, Sony, and others.

Sticking with the K10D's 11-point wide AF system was a good choice. With a 3x3 grid of cross-type sensors surrounded by a linear sensor, the array works with f/5.6 or brighter lenses.

In our Lab tests, the AF was very fast in bright light and sensitive in low light down to EV -1 (though slow by EV 0). In field tests, it tracked rapidly moving objects across a wide area of the frame. But it slows to more than 1 second at EV 1, and is sluggish at EV -1-not as fast nor as sensitive as the AF systems in several Canon, Nikon, and Sony DSLRs.

Pentax kept the K10D's viewfinder, with its 95 percent field of view and 0.94X magnification. You get a large, clear view and easy-to-read data display. And unlike nearly all of its competitors, the K20D has interchangeable focusing screens for specialty work, a bonus disappearing from some pro DSLRs.

On the metering side, we found the same, accurate 16-segment evaluative meter, centerweighted, and a 5-percent spot. In addition to these controls, the K20D also includes sophisticated white-balance, color-saturation, and exposure-compensation features. You can bracket white balance in either 3- or 5-shot sequences. The same choice applies to exposure compensation, with either 1/3- or 1/2-stop increments.

LIVE VIEW

The CMOS sensor allows a feature that's becoming as common on DSLRs as autofocus -- live view. Especially handy for macro work or when shooting over crowds, this tool is sure to be put to new uses as its popularity spreads.

On the K20D, live view is easy to activate -- just turn the power switch around the shutter button to the third position. (You must first enable this function in the custom settings, or the same switch will turn on the depth-of-field preview.) Once live view is on, you can set the focusing system to auto or manual through a switch near the lens barrel. In live view, pressing the shutter halfway doesn't activate the AF -- if you try, you'll take a picture. Instead, you must press the AF button on the back of the camera. This mode has the typical delay between pressing the shutter and image capture, caused by the mirror moving into place for a split second. So forget tracking a moving target.

Live view's manual-focus mode gives you up to 8X magnification to fine-tune the focus. Custom menu items let you set the live preview screen to display either a grid or an outline of the area containing the 11 AF zones.

BETTER IMAGE STABILIZATION

According to Pentax, the K20D has a sensor-shift mechanism similar to the K10D's, and offers up to 4 stops' advantage. But our tests confirmed that minor modifications and faster processors have improved the image-stabilization system by about half a stop over the K10D. Now, when shooting with a 200mm lens, you can expect a 2.5-3 stop advantage in shutter speeds compared to handholding the camera without image stabilization. With wider-angle lenses, the benefit decreases, and with longer focal lengths (or heavier lenses) the benefit may increase.

As with models from Olympus, the calming image-stabilization effect can be seen when the K20D is set to live view, a function that all image-stabilized lenses have in common.

Another noticeable improvement, especially for peace of mind, is that the sensor now locks more firmly into place when the camera is turned off.

Pentax understands that the versatility of a DSLR means that it might be exposed to adverse conditions. And the K20D is built to meet them. A tough plastic shell surrounds a rigid stainless-steel frame, and the body is shielded from moisture and dust by 72 gaskets -- including around the locking SD/SDHC door.

The controls are easy to reach and master, and menus are even clearer on the 2.7-inch screen, with its wide viewing angle and 230,000-dot resolution.

While changes to the electronics enable new features and controls, the modest burst rate of the K10D remains intact. In our tests, the K20D captured up to 38 Fine-quality JPEGs at 3 frames per second, or 14 PEF RAW files at 3 fps. At a slower speed, it captured 2.7 fps, allowing Fine-quality JPEGs to be shot until they filled a fast SDHC card. (Given the large image files from this 14.6MP camera, we wish there were a second slot for higher-capacity CF cards.)

One of the most innovative functions makes it easier to clean dust off the sensor. The camera identifies dust spots and enhances them on-screen, then reverses the screen horizontally and surrounds it with a graphic of the lensmount. Why? So when you turn the camera around to blow out dust you see the correct positioning.

Will all of these new capabilities, combined with the well-proven aspects of the K10D, be enough for the K20D to challenge the Canon EOS 40D? We think so, except at the upper ISO limits and in extremely low-light AF challenges. The price is competitive with -- or even below -- DSLRs in the nearby 12MP class, and it's built to outlast most lower-cost models.

COMPETITIVE SET

Canon EOS 40D ($1,150 street, body only) Yes, it costs less, but the 10.1MP Canon EOS 40D doesn't capture detail on par with the 14.6MP Pentax K20D (you get about 10 percent less). But fewer megapixels help give the Canon a burst advantage of 6.5 fps, versus the K20D's 3 fps, and its DIGIC III processor better reduces noise at ISO 1600 and 3200. The K20D is built to take similar abuse, but Canon's 9-zone AF system outguns the Pentax in low light, and its slightly larger (though not sharper) 3-inch LCD is a plus. Both cameras have live preview, but the Pentax also boasts sensor-shift image stabilization, a clear advantage over the EOS 40D. And the Canon pop-up flash still doesn't support wireless flash control -- advantage, Pentax.

Sony Alpha 700 ($1,350, body only) Images from the 12.2MP Sony A700 have slightly less resolution and detail than those from the Pentax K20D, but the image quality of JPEGs from the Sony is better at all ISOs due to higher color accuracy and, at high ISOs, lower noise. The Sony has a larger and higher-resolution 3-inch LCD, plus slightly superior sensor-shift image stabilization. The K20D appears to have a few more gaskets for greater resistance to water and dust, though the Sony's magnesium-alloy casing and aluminum-alloy chassis are built to last. The K20D's live preview mode might sway macro shooters towards it; the A700's faster, more sensitive AF system will definitely appeal to sports and action photographers.

VITAL STATISTICS

Imaging: 14.6MP effective, APS-C-sized CMOS sensor captures images at 4672x3120 pixels with 12 bits/color in RAW mode.

Storage: SD and SDHC. Stores JPEG, PEF RAW, RAW DNG, RAW + JPEG.

Burst rate: JPEGs (Fine mode): Up to 38 shots at 3 fps. RAW: Up to 16 DNG RAW at 3 fps. JPEG 1.3MP: Up to 115 shots at 21 fps.

AF system: TTL 11-point system. Single-shot and continuous AF. Tested sensitivity down to EV -1 (at ISO 100, f/1.4).

Live view: TTL Phase matching modes with short blackout time.

Shutter speeds: 1/4000 to 30 sec plus B (1/3-, 1/2-, or 1-EV increments).

Metering: TTL evaluative 16-segment metering (coupled with lens and AF information), centerweighted, and spotmetering (approx. 5%). EV 0-21 (at ISO 100). Exposure bracketing 3 or 5 frames in 1/3- or 1/2-EV steps.

ISO range: Normal: ISO 100-3200. Expanded: ISO 6400 (in 1/3-, 1/2-, or 1-EV increments).

Flash: Built-in retractable P-TTL pop-up flash. GN 43 (at ISO 100, feet). Hot-shoe, X-sync socket, sync-speed: 1/180 sec, P-TTL, high-speed-sync, wireless-sync with Pentax dedicated flash.

Image stabilization: Image sensor shift mechanism, 2.5-3 stops' advantage.

Viewfinder: Fixed eye-level pentaprism.

LCD: 2.7-in. TFT with 76,700-pixel (230,000-dot) resolution, 170-degree viewing angle.

Output: Hi-Speed USB 2.0, NTSC/PAL video.

Battery: Rechargeable D-LI50 lithium ion battery, CIPA rating, 720 shots, half with flash.

Size/weight: 5.6x4.0x2.76 in., 1.87 lb with battery and SD memory card.

Street price: $1,299 (estimated), body only.

For info: www.pentaximaging.com.

VIEWFINDER TEST

Accuracy: 95% (Excellent)

Magnification: 0.94X (Excellent)

Pentax-K20D-1-500-f-4-ISO-400-The-Pentax-K20D

Pentax-K20D-1-500-f-4-ISO-400-The-Pentax-K20D

1/500 @ f/4 ISO 400: The Pentax K20D did a nice job of evaluative metering for the range in this scene.Photo By Jack Howard
Pentax-K20D-1-50-f-4.5-ISO-400-We-had-to-sligh

Pentax-K20D-1-50-f-4.5-ISO-400-We-had-to-sligh

1/50 @ f/4.5 ISO 400: We had to slightly warm up the tones on this shaded street scene.Photo By Jack Howard
Pentax-K20D-1-80-f-4.5-ISO-400-We-exposure-loc

Pentax-K20D-1-80-f-4.5-ISO-400-We-exposure-loc

1/80 @ f/4.5 ISO 400: We exposure-locked on the window display and recomposed for our chosen angle, s that the main area would be properly exposed, while the bright sunlit edge and background get blown out a little in this high-contrast scene.Photo By Jack Howard
Pentax-K20D-1-320-f-4.5-ISO-400-The-Pentax-K20

Pentax-K20D-1-320-f-4.5-ISO-400-The-Pentax-K20

1/320 @ f/4.5 ISO 400: The Pentax K20D did a nice job of keeping detail throughout the tonal range in this fisheye scene.Photo By Jack Howard
Pentax-K20D-1-250-f-4.5-ISO-100-We-had-to-warm

Pentax-K20D-1-250-f-4.5-ISO-100-We-had-to-warm

1/250 @ f/4.5 ISO 100: We had to warm up the color in this shaded ice rink shot to neutralize a cool blue cast.Photo By Jack Howard
Pentax-K20D-1-160-f-4.5-ISO-100-Again-we-need

Pentax-K20D-1-160-f-4.5-ISO-100-Again-we-need

1/160 @ f/4.5 ISO 100: Again, we needed to warm up this shot a little to minimize the bluishness of the ice in the shaded foreground.Photo By Jack Howard
Pentax-K20D

Pentax-K20D

Pentax K20DPhoto By Jack Howard
Pentax-K20D-1-640-f-8-ISO-200-There-s-great-de

Pentax-K20D-1-640-f-8-ISO-200-There-s-great-de

1/640 @ f/8 ISO 200: There's great detail in this low ISO scene of Mandalay Bay in Las Vegas.Photo By Michael J. Mcnamara
Pentax-K20D-1-15-f-4-ISO-200.-Yes-that-s-1-15

Pentax-K20D-1-15-f-4-ISO-200.-Yes-that-s-1-15

1/15 @ f/4 ISO 200. Yes, that's 1/15 of a second, handheld, courtesy the sensor-shift stabilization. Notice the great shadow details.Photo By Michael J. Mcnamara
Pentax-K20D-Pixel-Comparison-We-shot-this-street

Pentax-K20D-Pixel-Comparison-We-shot-this-street

We shot this street scene at ISO 100, 800, 1600, and 3200 on the Finest Quality JPEG setting at full 14.6 megapixel resolution. We've pulled the same areas up to 100% pixel views in the next slides.Photo By Jack Howard
Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

The same scene at ISO 100, 100% pixel view.Photo By Jack Howard
Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

The same scene at ISO 800, 100% pixel view.Photo By Jack Howard
Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

The same scene at ISO 1600, 100% pixel view.Photo By Jack Howard
Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

Pentax-K20D-Pixel-Comparison-The-same-scene-at-IS

The same scene at ISO 3200, 100% pixel view.Photo By Jack Howard
ADVERTISEMENT