Performance - How well does it take pictures?

Ultimately, it is the image quality that makes a camera worth buying. For an SLR, image quality greatly depends on the lens used. While color, noise, exposure and contrast are properties of the camera, distortion, vignetting and chromatic aberrations are properties of the lens. Sharpness depends on the weakest link. That is, the camera cannot capture more details than the lens lets through. Conversely, it is possible for a lens to transmit more details than the sensor can capture.

Exposure is generally good with the K20D, specially with subjects that fall within the camera's dynamic range. When a subject has more contrast then the K20D can capture, it consistently exposes conservatively. This means that highlights are rarely overexposed but images may appear darker than expected. Since this is not optimal for printing unmodified images, more positive exposure-compensation than usual is required for scenes with very bright highlights.

Changed from the K10D: The Pentax K20D shows good hue accuracy but does not produce exact color saturation. Specifically, the neutral setting is slightly undersaturated while the next higher setting is just a bit oversaturated. The K20D has 6 color modes, five of which are just presets of image parameters, plus one monochrome mode.

New to the K20D: Color saturation, hue and contrast can be adjusted in 9 steps independently of each other with a relatively wide latitude. There are a total of 18 sharpness settings available on the K20D. They are paired as 9 standard sharpness settings and 9 fine sharpness settings. Standard sharpening shows wider edges than fine sharpening. This provides exceptional precision for controlling image sharpness. Fine-sharpness +2 produced the most pleasing results with virtually no visible artifacts.

New to the K20D: Pentax has provided an excellent interface for setting image parameters. The main feature is a digital preview which is dynamically updated whenever an image parameter is changed. Another important detail is that the K20D changes the color of any setting that is not at its default value to yellow. Settings at their default values are shown in green. The final touch is a 6-sided color space representation which shows how colors are affected by image parameters.

The white-balance system is very accurate when preset and manually set. Automatic white-balance is generally good except under artificial light where it leaves a warm color cast. Unfortunately, this problem occurs with most digital SLR cameras. However, since the K20D has a digital white-balance preview feature, it is very easy to select an accurate white-balance and fine-tune it until satisfied.

Noise levels are extremely low until ISO 400, very low but noticeable in shadow-areas at ISO 800 and low at ISO 1600. The K20D reaches higher ISO sensitivities than it predecessor: ISO 3200 is quite noisy with a slight color shift due to chroma-noise. Still, small prints at ISO 3200 should be possible. ISO 6400 is very noisy and probably is not worth using. Compared to other high-resolution DSLR cameras, the Pentax K20D is about average in terms of image noise but it manages to keep more detail than most. There are some cameras which take the opposite approach and smooth-out both noise and details heavy-handedly. Pentax, on the other hand, has taken the bold step of providing a camera with noise-reduction disabled by default. People who prefer the other approach can enable the desired level of noise-reduction.

In operation, the Pentax K20D is speedy and responsive. There is rarely a moment where the photographer has to wait for the K20D. The focusing system is very fast and accurate, with some variation depending on the lens used. Shutter-lag is always instant. Image playback and zoom is fast as well.

The K20D officially shoots continuously at 3 FPS but we found that shooting in high-speed continuous-drive varied somewhat. New to the K20D: There is a low-speed continuous drive which hits 2 FPS more consistently. Finally, the K20D has a 20 FPS burst-mode which captures images at 1.5 megapixels without flipping the mirror. Instead, the LCD screen is used as a coarse preview. No information is displayed while shooting in this mode.

Although there is no formal procedure for measuring the performance of image stabilization, we can say that the Shake Reduction system in the K20D appears to be normally effective to at least 2 stops, with 3 stop of effectiveness being quite common and 4 stops a hit-or-miss.

Pentax has made some changes to the K10D's Shake Reduction system which results in slight performance differences between these two cameras. Broadly, the performance is very close on average. It took hundreds of test shots to accurately understand the subtlety. The K10D's Shake Reduction is more consistent at each stop but its effectiveness drops faster. Case in point, the K20D produced more sharp shots at 4 stops over the normal hand-holding limit but the K10D produced more sharp shots at 2 stops.

Pentax K20D vs K10D

Externally the Pentax K20D is remarkably similar to the K10D. Noteworthy changes include the addition of a sync-port and an LCD measuring 2.7" diagonally rather than 2.5". Internally, besides the new sensor, there are a number of evolutionary changes:

 

Image parameters have been expanded and moved from the Recd Mode menu to the Fn menu. The K10D has two color modes, Bright and Normal, each serving as a baseline for adjustment of saturation, sharpness and contrast in 7 steps. These steps have a fine granularity and therefore that image parameter range has a narrow latitude. The new K20D now has 5 color modes which serve as presets for adjusted image parameters. Each of saturation, hue and contrast are adjustable in 9 steps. These steps have a coarse granularity which gives a wide adjustment range at the expense of precise control. Sharpness is handled different with two modes of 9 steps each, thus giving very fine control over image sharpness. Sharpness was the most serious area of criticism when the K10D came out, so this is a very welcome change. There is also a monochrome mode on the K20D with several adjustable parameters.

 

Two new drive modes appear in the Fn menu. One is a low-speed continuous drive which shoots at 2 FPS instead of 3. The other is a burst-mode drive which shoots 1.5 megapixels images at 20 FPS without flipping the mirror. Since the viewfinder is blacked out during that mode, live-view automatically becomes active. Speaking of which, live-view is new to the K20D but is extremely limited. In practice, It is only usable for focusing manually and precise framing. There is also an Interval mode which can shoot up to 99 images at intervals between 1 second and 24 hours.

 

Image quality is selectable in 4 steps, versus 3 steps on the K10D. As expected, there is an additional resolution to chose from (14.6 MP), in addition to 10, 6 and 2 MP. The K20D also has an extended bracket for Hue.

 

Pixel Mapping and Dust Alert have been added since the K10D. The former is used to avoid damaged pixels on the sensor, while the latter is used to detect dust on the sensor. Since the Dust Alert never reported anything here, it is difficult to say if the Dust Reduction feature is effective or if he Dust Alert is not.

 

Two text sizes are available for the active menu item: standard and large. There is also a way on the K20D to tune LCD colors, just like white-balance fine-tuning. It is also possible to choose the first four letters of image file names.

 

Several custom settings have been added to make the K20D more customizable than its predecessor:

• Expanded ISO sensitivity replaces the ISO Warning on the K10D. This determines if the maximum ISO is 6400 or 3200.
• One-Push Bracketing is a new option that lets a bracket be taken with a single release of the shutter.
• Fine-Tune AWB is replaced by WB Adjustable Range on the K20D. This option specifies if the white-balance is automatically adjusted or fixed.
• There are now 4 levels of high-ISO noise reduction: Off (default), Weakest, Weak and Strong. The steps are rather coarse here as weak is considerable stronger than weakest.
• Which dial adjusts aperture in TAv & M and B & X mode is selectable.
• There is an option to display sensitivity in the viewfinder and LCD.
• Catch-In focus can be enabled so that the camera captures an image when something appears in focus in manual focus mode.
• Autofocus adjustments can now be made to compensate for lens-dependent focusing errors.

The big change is the sensor which features increased resolution to 15 megapixels (14.6 MP effective, up from 10.2 MP) and ISO sensitivity up to 6400. There is also a 200% dynamic-range mode which features sensitivities from 200 to 6400 and adds one stop of details in image highlights. Due to larger image sizes, the unlimited drive of the K10D is gone. Still, the K20D manages a respectable 38 JPEG or 16 RAW in a single burst.

Wish List

Since no camera is perfect, here are our suggestions to Pentax for improving upon the K20D:

• Large 100% coverage viewfinder.
• Automatically rotate the sensor to keep lower image edge parallel to the horizon.
• Revise the Shake-Reduction system to increase its efficiency and consistency.
• Improve image noise at high-ISO, even at the expense of a few megapixels.
• Improve automatic white-balance accuracy under artificial light.
• Add metering-line options (normal, shadow, highlights) for all metering modes.
• Additional focus modes: infinity and hyper-focal.
• Allow reset values to be specified for parameters reset at power-off.
• Automatically reset the 12-second self-timer after each use.
• Add an option to disable the flashing Flash icon.
• Add an eye-start sensor to automatically turn off the LCD when the viewfinder is in use.
• Move to standard AA batteries like the K200D.

Conclusion

As an evolutionary step to the excellent K10D, the Pentax K20D remains an excellent camera. Only the continuous buffer limit has been reduced, everything else has either been improved or remained the same. While the Pentax K20D remains one of the best cropped-sensor DSLRs around, the competition has gotten hotter and there are now greater differences between flagship models.

This feature-rich DSLR leads its class in terms of resolution and produces images full of details while keeping noise in check. This makes it one of the best cameras for most non-action photography. Its truly superb ergonomics make very efficient in use, plus it nearly always responds instantly.

The action photographer, however, will be more attracted to a DSLR that can shoot at 5 FPS or more, of which there are now several. Another area where the K20D lags behind the competition is its viewfinder coverage which is at 95%, while both the Nikon D300 and the Olympus E-3 provide 100% coverage.

One of the K20D's sore points is the performance of its built-in stabilization system which is not as reliable as advertised. Since there are no stabilized Pentax lenses, nothing can be done if it does not provide sufficient stabilization.

The bottom line is that the K20D has one of the most complete feature set of any DSLR. It brings some unique features and exposure modes into a very thoughtful and ergonomic design. Plus, since image quality and performance are great, there is no doubt the K20D is a worthy digital SLR.

• See outdoor crops
• See indoor crops
• See sample image gallery

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