Pentax K20D Digital SLR Review
Last updated on 12/03/2010
The Pentax K20D earns this reviewer's highest recommendation, presenting a strong and affordable alternative to SLR titans like Canon and Nikon.
By Joseph Ben Keough
Once an industry titan with its legendary Spotmatic, K1000, and LX models, Pentax stands in the 21st Century as a bit player in the dSLR field. With Canon and Nikon each controlling roughly 40% of the market, Pentax is a distant fifth in the sales charts with a paltry 2%, behind both Olympus and an ascendant and big-spending Sony. Still, the brand has a devoted following, and has been steadily forging its own path through the dSLR jungle. While the big two focus on autofocus speed, powerful zoom lenses, and professional-grade equipment, Pentax caters to entry-level photographers and to advanced amateurs who primarily shoot landscapes and portrait photos.
The K20D is the newest and most powerful camera in Pentax's dSLR line, replacing the earlier K10D. A serious amateur camera, it is equipped with a 14.6-megapixel CMOS sensor co-developed with the company's partner Samsung, who have released a near-identical camera in their GX-20. With a street price hovering around US$700, it is an enticing entry into the same market segment dominated by the Canon 40D and Nikon D300. In this review I'll take you through the K20D's highs and lows, and attempt to place it in context with the competition.
Body and Styling
This is a handsome, heavy camera, with a solid build quality more reminiscent of cameras in the pro realm than its direct competitors. With the battery installed, the camera weighs roughly 1.7 pounds. It's pleasantly chunky as well, with good ergonomics and a well-balanced heft. An optional battery grip provides even better balancing, and, as you would expect, significantly extends battery life. This is not a lightweight camera a la the Nikon D40, or Pentax's own K2000/K-m, and potential buyers should take this into account when considering it; as always, try to get your hands on an in-store model before making your choice.
The layout of the K20D will be instantly familiar to users of past Pentax dSLRs, with a few added bells and whistles. The front of the camera is largely clean, with the lens-release button at the lower left of the mount. On the right-hand side of the lens housing is a three-way switch that controls the camera's focus mode, allowing the user to select AF.S (one-time autofocus), AF.C (continuous autofocus), or MF (manual focus). This switch works for all K-mount AF lenses, though some newer lenses may also have an on-lens AF/MF override switch. Just above the focus control switch is a RAW button, which is user-configurable to switch between JPEG, RAW, and RAW+JPEG recording.
At the top left of the camera you'll find the shooting mode selector dial, which offers options for Green (aka full-automatic), Program, Sv (sensitivity priority), Tv (shutter priority), Av (aperture priority), TAv (shutter and aperture priority), Manual, Bulb, Flash-sync, and User-programmable modes. The Sv and TAv modes are unique to Pentax, and offer interesting methods for shooting. Sv mode allows the user to set the ISO and allow the camera to control the rest of the exposure settings. TAv mode combines user-defined shutter and aperture settings with camera-controlled ISO. Below the mode selector dial is a selector ring for the camera's metering options, allowing the user to choose between Multi-segment, Center-weighted Average, and Spot-meter.
The in-body pop-up flash, flash release button, and hotshoe occupy the top center portion of the camera. On the right is the power switch, which surrounds the shutter release. The power switch may be turned past the ON position to activate a depth-of-field preview, which can be done either optically (in the viewfinder) or using the camera's live-view mode, on the rear LCD. On the front of the camera, just below the power switch, is the front dial, which controls various settings in the various modes (usually the shutter speed). To the left of the power switch is the "green button," familiar from many Pentax SLRs. Pressing the green button will auto-set the exposure settings for the current light conditions, which is handy when using a full-manual lens in the camera's manual mode. A large top-mounted and backlit LCD gives a real-time readout of current camera settings, including most of the vital information you'd need at a quick glance.
The back of the camera is positively packed with controls. To the left of the viewfinder is a toggle button controlling single/continuous shooting. Lining the left side of the LCD screen are four buttons: Menu, Trash, INFO (which toggles histogram and shot information overlays when in playback mode and brings up a more detailed settings display when in shooting mode), and Playback. On the right side is the rear dial, which, like the front dial, controls various settings in various modes. In Manual, Program, Av, and TAv modes, it controls the aperture; in playback it controls the zoom level. Joining it on the right rear are an AE-Lock button, an exposure compensation button (which also illuminates the top LCD display's backlight), and an AF button. By default, the AF button activates autofocus, just as a half-press of the shutter release does; the button can alternatively be configured to disable autofocus.
Below these buttons, a four-way control dial surrounds an OK button; these are used to navigate through the camera's various menus. Surrounding this four-way dial is a ring that allows the user to choose between three autofocus modes, including center-point, user-selected single-point (from 11 available), or automatic (which chooses the most applicable of the 11). Finally, below this ring are a Function button, which accesses vital shooting-related options including white balance and ISO, and the on-off switch for the camera's in-body shake-reduction (SR) system, comparable to Canon's in-lens image stabilization (IS) and Nikon's in-lens vibration reduction (VR).
The camera's 2.7-inch, 230,000-pixel rear display features adjustable brightness, 32x zoom in image playback, and the ability to color-correct. In general, it's a fine display that is well-matched to the abilities of the camera, but there are others in the market that outclass it. The viewfinder, on the other hand, cannot be outclassed. Its glass pentaprism is a class-leader, with a big and bright display that covers 95% of the recorded image. The viewfinder also includes the standard status bar indicators, which convey important information like shutter speed, aperture, ISO, focus mode, and so on.
With 36 options in its custom control menu, the K20D has no shortage of features and settings for the enthusiast to dabble with. These settings allow the user to customize nearly every setting on the camera, including exposure compensation step size, ISO sensitivity step size, white balance range, and so on. These options also allow the user to configure the function of several on-body buttons, tailoring the controls to suit his or her shooting style.
Image controls allow the user to specify saturation, hue, contrast, sharpness, and "fine sharpness" levels. Six pre-defined color settings can be chosen, including Bright, Natural, Portrait, Landscape, Vibrant, and Monochrome, each tailored to provide a certain look in a certain setting. Further, the user can alter the five configurable settings in each of these modes to suit their tastes. Pentax dSLRs tend to play it safe with factory default settings, using low sharpening, contrast, and saturation in comparison to their competitors. While this is ideal for more advanced users who plan to shoot in RAW mode and post-process their images, for casual shooters it can mean soft JPEGs with lower-than-normal contrast and saturation. New users are encouraged to play with the settings to find the configuration that suits them best. Additionally, the K20D features the world's first color-adjustable LCD display, meaning that the user can ensure a display free of color bias; very important when using the custom white balance setting.
The implementation of live-view on the K20D is a first for Pentax, and it leaves much to be desired in comparison with the current offerings from Olympus and Sony, feeling tacked on as a marketing gimmick. But it does provide a basic live preview and live-capture mode using the big and bright rear LCD.
In-body shake-reduction is one of the Pentax dSLR line's biggest selling points, and for good reason. With in-body stabilization, all lenses mounted to the camera are functionally stabilized lenses. Paired with the K20D's legendary reverse-compatibility, this means that a range of thousands of K-mount lenses stretching back to the 1960s can be used natively on the body, with full stabilization. Further, M42 and Leica M39-mount glass from the 1950s can be used, with the use of special mount adapters. When a manual-focus lens is mounted to the camera, the LCD will prompt the user to select the lens's focal length in order to calibrate the shake-reduction. For autofocus lenses, this procedure is invisible and automatic. An additional advantage of in-body SR over in-lens stabilization is that it means lenses can be smaller and lighter, as well as substantially cheaper. Of course, the actual effect of the shake-reduction system is that you can shoot at substantially lower shutter speeds or substantially tighter apertures (some have reported up to 4 stops of difference) without worrying about motion blur. This is wonderful for low-light shooting.
One major and notable feature of the K20D's body design is its dust and weather sealing, which is evidenced by its rubber o-ring-sealed battery and SDHC card compartments, which are closed behind locking hatches. In addition, various lenses in the Pentax lineup include lens-based dust and weather sealing, making the K20D one of the best options on the market for all-weather shooting. The camera's sensor can also be configured to shake upon camera start-up, reducing or eliminating on-sensor dust.
The K20D allows the user to select between JPEG and RAW recording, or to use a combined RAW+JPEG setting. In JPEG mode, the camera can record at its native 14.6 megapixels, or can be downscaled to 10, 6, or 2 megapixels, if you need to conserve memory card space. There are four JPEG quality settings, which determine the amount of compression used on the images. Transitioning over from the K10D are Good (*), Better (**), and Best (***), and new with the K20D is Premium (****). The Premium setting records with a minimal compression ratio (1:2.8), which results in extremely large file sizes (approximately 12mb per JPEG). These files, however, are dwarfed by the two RAW recording modes. Users can choose between Pentax's own PEF RAW recording, or the universal Adobe DNG RAW format. DNGs are the largest recordable images from the K20D, weighing in at a hefty 22.3mb per. The Pentax PEF files are significantly smaller, weighing in at half that size, but at a sacrifice of compatibility across image editing programs.
One truly professional feature of the K20D is the ability to manually compensate for lens front or back-focusing (autofocus that is consistently slightly in front of or behind the subject), on a lens-by-lens basis. This is a known issue on many manufacturer's bodies and lenses, and it's wonderful to see that Pentax has made it easy to compensate for it. To activate this option, the user should simply go to option 35 on the custom menu.
A last neat little addition is Dynamic Range Expansion, which works to prevent "highlight clipping," also known as blown-out areas in whites and other bright areas. Without affecting the shutter speed or other exposure settings, it works to selectively decrease the exposure in bright areas and increase it in lighter areas; a sort of HDR-lite option.
Shooting Performance and Image Quality
Pentax dSLRs are traditionally a mixed bag in terms of performance. While they can produce stunning image quality, sometimes getting there can be a bit of an ordeal. Most importantly, the Pentax autofocus system is known to be notoriously slow compared to that of the big two. This, along with aggressive advertising from Canon and Nikon, has led the majority of pro photographers to choose their products over Pentax's and the other dSLR also-rans, especially when it comes to sports and wildlife photography. However, while the K20D doesn't clear all of the brand's hereditary hurdles, I am glad to say that it is a joy to shoot with.
Part of the reason for the slower autofocus on Pentax dSLRs is that very few Pentax lenses use in-lens autofocus motors. Instead, the vast majority rely on a slotted screw-drive motor housed in the camera body. While this does ensure that all AF lenses ever made for the K-mount work with Pentax dSLRs, it is not as quick as in-lens AF. Recent Pentax and third-party lenses, however, have introduced SDM technology using a supersonic in-lens motor. Users have also found that on older non-SDM lenses autofocus speed can be increased by using center-point AF rather than automatic autofocus mode. Finally, a "trap-focus" mode has been added to the K20D, which avoids the sometimes-annoying "focus check" that is a trademark of Pentax AF cameras. With all of this said, the K20D is never distractingly slow in AF terms, even in AF.C; it's simply not as quick as the competition.
Like most dSLRs, the K20D has near-instant startup times, and zero shutter lag when pre-focused. The dual-dial system makes manual shooting a breeze, especially when paired with the green button's auto-exposure functionality, which essentially functions as an aperture priority mode for full manual lenses. The control layout on the camera is near-ideal for most shooting situations, with the buttons laid out just where you need them, and with the ability to customize their functions to your tastes.
As in other Pentax dSLRs, the continuous shooting rate is subpar by market/class standards. The K20D gets 3 frames per second when shooting at full resolution, with a 14-image RAW buffer or a 38-image JPEG buffer. Other cameras in this class offer upwards of 5fps, with a larger buffer, but it seems unlikely that the majority of the K20D's users will notice the difference.
The built-in flash is not especially powerful, but produces wonderful flesh tones in dim-environment close-ups, and has little to no recharge time. Unfortunately, like other Pentax dSLRs before it, the K20D lacks an AF-assist lamp, and instead uses the pop-up flash as a strobe to illuminate the scene and lock on with the AF system. This works quite well, but it has the unfortunate side effect of blinding your subjects if they're human, and can lead to many squinty-eyed photos. Pentax offers a nice range of hotshoe flashes of varying power and customizability, and they are quite affordable. Moreover, the K20D includes a flash sync socket, which is ideal for studio photographers using slave strobes.
One of the finest improvements made with the K20D is in the realm of high-ISO performance as it relates to image noise. Shooting at ISO 1600 with the camera is a revelation, as it produces hardly any noticeable image noise while retaining a very good degree of detail. Even at ISO 3200 the image quality is quite good. At ISO 6400 (which must be enabled via the custom settings menu) things begin to get a little grim, but as a former K100D owner, I can say that ISO 6400 on the K20D is roughly equivalent to ISO 1600 on the older model. This is quite an achievement, and could even be called a triumph when considering that the K20D boasts a sensor that packs in more than double the older camera's pixel count.
As discussed above, the camera's default settings can lead to soft, under-saturated JPEG images, even at the highest JPEG quality levels. With that out of the way, I'm glad to report that with a little tinkering the camera can produce JPEGs on-par with the best of the cameras in its class. Moreover, shots developed from RAW indicate that the K20D's IQ, independent of the lens used, is easily on par with, and possibly even a few steps above, competing brands models.
The kit lens included with the K20D is the SMC Pentax-DA 18-55mm f/3.5-5.6 AL II, the successor to the kit lens used on the *ist DS through the K10D. It was developed because Pentax felt the new sensor in the K20D was outmatching the old kit lens's resolving power, and so it features improved optics and lens coatings. In general, it produces very good image quality throughout its range. As is usual with lower-end zooms, it is somewhat softer at either extreme end of its zoom range, but it is a capable walk-around lens with a nice film-equivalent range of coverage (approximately 27 to 83mm, or moderate wide angle to moderate telephoto). Moreover, it is easily among the top kit lenses offered by any of the major dSLR manufacturers; really quite a steal.
Another Important Consideration: The Lens System
Speaking of lenses an important thing to consider when choosing a dSLR is the lens system you're buying into. Since nearly all dSLR manufacturers use their own proprietary lens mount, once you buy a digital SLR body, you are locked into buying the lenses made for that mount. Consumers often have several third-party manufacturers to choose from as well (such as Sigma, Tamron, and Tokina), and these companies often produce fantastic glass, but they tend to look to the first-party manufacturer for inspiration and guidance as to the sort of lenses they will produce for a given system.
As mentioned in the performance section of this review, the Pentax system is often derided for its lack of fast (meaning low-light-capable) AF zoom lenses in comparison to the Canon and Nikon systems. However, the company has a strong tradition of producing fast prime (fixed-focal length) lenses, which are ideal for landscape, street, and portrait photography, and are the envy of other systems. In recent years the Pentax lens system has expanded substantially, bringing in a large number of semi-pro or pro lenses in the FA*, DA*, and Limited lines.
Pentax's DA (APS-C/digital-only) Limited lenses boast all-metal construction and superior optical quality, and take the APS-C digital system's 1.5x crop factor into account, using odd focal lengths including 15mm, 21mm, 35mm (macro), 40mm, and 70mm to produce an ideal focal length distribution in 35mm film focal length terms. This is a lens lineup that cannot be matched by any other manufacturer. Indeed, no other manufacturer at the moment seems interested in focusing on prime lenses, which is perhaps a wise decision in a market where the average consumer doesn't ever buy more than one additional lens, almost always a zoom.
However, Pentax appears dedicated to their chosen path, and this is a boon for those customers who enjoy the superior optical quality of prime lenses. In addition, the company has recently produced a number of DA* lenses, which are marketed as professional-grade glass and offer exceptionally wide apertures with extremely high-quality optics. This line includes both prime and zoom lenses, and follows in the footsteps of the successful and much-revered FA* line (for full-frame film SLRs, but also usable on Pentax dSLRs).
In short, and at the risk of repeating myself one time too many, you must understand what you're buying into when you buy a dSLR. While one manufacturer may excel at quick autofocus and long zooms, another may specialize in fast prime lenses that are ideal for portraiture. The savvy consumer will consider the type of shooting he or she does most, and which lens system suits those pursuits best.
The K20D is a very impressive advanced amateur dSLR, especially considering its price point and the relatively low cost-of-ownership for a typical Pentax system (body, lenses, accessories). Its image quality, particularly when the default JPEG settings are adjusted or the user chooses to shoot in RAW mode, are stellar; easily the equal of its direct competitors. High-ISO performance is a revelation, allowing worry-free shooting up to ISO 1600 and getting quite usable results even at ISO 3200. While the selection of new top-end lenses may not approach that available to Nikon or Canon shooters, the wealth of natively-mountable older glass is unmatched, and a serious consideration for a shooter on a budget. Finally, the camera features an incredibly in-depth array of custom settings, allowing the user to essentially reconfigure many of the controls and design a layout that best suits his or her needs.
Despite all of these plusses, the K20D does have a few weak spots that need to be addressed. While obviously not essential for portrait or landscape shooting, an improved autofocus system and a larger continuous shooting buffer would make the camera much more appealing to users who are interested in shooting moving objects. The camera's in-body flash is pretty good, but the lack of an AF-assist lamp is a silly oversight by the engineers at Pentax. One issue not noted in the above sections is the continued poor auto-white balance performance under incandescent light. While this is an admittedly tricky problem to solve, the camera's designers have had five or six generations to get it right and they're still off by a country mile. This is easily correctable in post-processing, especially when shooting in RAW, but it's annoying nevertheless. Finally, the camera's live view is more a marketing gimmick than a truly useful feature (though in this reviewer's opinion, live view is antithetical to the idea of an SLR to begin with).
All in all, this is in my opinion easily the best value for your dollar in its class, and a great tool for honing your photographic craft. The build quality is dependably solid, the image quality is fantastic, and the possibilities are endless. With the above-noted caveats, I give the K20D my highest recommendation.