Pentax K-x Overview
by Mike Tomkins, Shawn Barnett,
and Zig Weidelich
Hands-on Preview Posted: 09/17/2009
Review Posted: 03/09/2010
Pentax announces its second digital SLR camera of 2009, the Pentax K-x, a new consumer digital SLR kit that's packed with features but with a sub-$650 price tag. Four body colors are available, the standard black or white, plus "special, limited edition" red and navy bodies.
Coming with an 18-55mm kit lens, the Pentax Kx is a 12.4-megapixel camera with sensor-shift image stabilization, a 2.7-inch LCD, Live View mode, and a 720p movie mode. Capable of 4.6 frames per second, the Pentax K-x's top shutter speed is 1/6,000 second.
Though the camera includes Pentax's 11-point SAFOX VIII AF system, it is hampered inexplicably by the lack of an AF-point overlay in the optical viewfinder, which means there's no visual confirmation of which points are in focus.
Surprisingly the Pentax K-x also includes the K-7's HDR modes, and it also has the Digital filters, as well as a new Cross Process mode that randomly emulates several results that you'd only get by cross-processing film with different types of developer.
Small and light, the Pentax K-x seems like a well-built, no-nonsense digital SLR, with perhaps only one flaw: the lack of visible AF points.
Pentax Kx price and availability. The Pentax K-x digital SLR will initially be available from October 2009 in three different kit versions, and two body colors -- either black or white. The most affordable kit version will include an smc Pentax DA L 18-55mm zoom lens for a total price of around US$650. Two twin lens kits will couple this 18-55mm lens with either an smc Pentax DA L 50-200mm zoom lens for about $750, or with a new smc Pentax DA L 55-300mm zoom lens for approximately $850. As with the previously announced DA L lenses, the new lens is a variant of an existing lens with certain alterations made to reduce weight and cost, such as the use of a plastic lens mount. Two unusual limited edition Kx body colors -- red or navy blue -- will also be available in limited distribution, with details on those versions to be announced at a later date.
Pentax K-x User Report
by Shawn Barnett and Mike Tomkins
After wowing us earlier last year with the Pentax K-7, we're surprised to see Pentax back at it so quickly with the light and nimble Pentax K-x. The Pentax K-x's list of features is impressive, including much of what was introduced on the K-7. The only potential downfall is the lack of an AF-point display overlay, something also missing from the K2000, which means that no LEDs will light up in the viewfinder when you half-press the shutter button to focus. Its omission leaves me scratching my head, and threatens to color the tone of our review. Since almost every other camera on the market gives some kind of indication of what areas are in focus before I commit to a shot, this just feels like I'm using a broken camera. While the K2000 also didn't have indicators, it didn't have 11 autofocus points covering a large percentage of the frame, so the potential for error was smaller.
Look and feel. The Pentax K-x has very nearly the same body as the K2000. A few buttons are reassigned to accommodate Live View and Movie modes. When loaded with lithium batteries, the K-x weighs 20.5 ounces (581 grams) -- a full six ounces (170 grams) lighter than the magnesium alloy-bodied K-7. A significant part of that savings comes thanks to the Kx's use of a fiber-reinforced plastic polymer body over a stainless steel chassis, and the exclusion of any weather sealing. The K-x's body is also about 0.2 to 0.3 inches (5 to 8 millimeters) smaller in every dimension than the K-7, and is among the smallest true digital SLRs available.
Though it's small, the Pentax K-x's grip is good, with an ample thumbgrip on the back. The notch for the middle finger is a little too small, but I'm glad it's there. Just under the X in Pentax there's a hole for the microphone to accommodate movie mode. An infrared port is imbedded into the grip.
On the top deck, you can see the two speaker holes just left of the flash. The Mode dial now includes Movie mode; unfortunately, it also turns too easily, accidentally jumping from mode to mode as I move it in and out of my camera bag. What was once the "?" or help button on the K2000 is the Green button that re-centers exposure and metering settings depending on the mode.
The Info and Menu buttons have moved down to make room for the LV (Live View) button, and the Flash pop-up button now doubles as the Delete button when in Playback mode. From here you can also see the power indicator lamp on the top deck, which shines a bright blue instead of the K2000's green.
A new graphical Status display not only outlines the camera's current exposure settings, but shows the current settings for four of the five navigation buttons on the camera's lower right, a great use of the large LCD. With a glance you can see that in this case the camera is in Single shot mode, Custom white balance, Center AF point, and Manual Flash-on (when the flash is popped up). Only the ISO button remains unchanged, since the ISO status is displayed to the left.
Sensor and processor. Compared to the K2000, the Pentax Kx upgrades both the image sensor and processor. The Pentax Kx's RGB Bayer-filtered 3:2 aspect ratio CMOS image sensor has 12.4-megapixel resolution, placing it exactly halfway between the resolutions of the 10.2-megapixel K2000 and 14.6-megapixel K-7.
With dimensions of 23.6 x 15.8mm, the new sensor is approximately the same size as a frame of APS-C film, and a fraction of a millimeter larger in each direction than those used in the K-7 and K2000.
The new imager is coupled with the company's latest generation PRIME II image processor, which debuted in the K-7 and offers improvements in both speed and image quality. Impressively, the Pentax Kx bests the equivalent ISO sensitivity offered by both the K-7 and K2000, with a maximum sensitivity of ISO 6,400 which can be expanded to ISO 12,800 if needed.
Shake Reduction. The image sensor of the Pentax K-x is mounted on a moveable platter which allows it to be used to provide for sensor-shift shake reduction, helping to reduce image blur from camera shake. Unlike lens-based systems, the Pentax K-x's in-body stabilization functions with pretty much any lens that can be attached to the camera. Pentax's marketing materials claim the system offers a potential four-stop improvement -- the same as that of the K-7 and K2000.
Like almost all shake reduction systems, the Kx's shake reduction can correct only for horizontal or vertical motion, but not for rotation -- a rare capability that is offered by the K-7. In place of the newer ultrasonic DR II system from the flagship, the K-x retains the previous generation of dust removal as seen in the K2000. This dual-pronged approach couples Pentax's Super Protect fluorine coating on the low-pass filter to help prevent dust adhesion, and use of the sensor-shift mechanism to shake dust particles free. The K-x also includes Pentax's Dust Alert function, which helps the user determine the location of any dust on the sensor for manual cleaning.
Lens mount. On its front panel the Pentax Kx features a stainless steel Pentax KAF2 bayonet mount which allows use of KA, KAF, KAF2, or KAF3 lenses. The K-x can also accept K-mount, 35mm screwmount, and 645 / 67 medium format lenses with an adapter and some usage restrictions. The Kx is compatible with Pentax's Supersonic Drive Motor (SDM) lenses, but doesn't support power zoom functionality on lenses with this feature.
Viewfinder. The Pentax K-x retains the K2000's pentamirror viewfinder with 96% coverage and 0.85x magnification, as well as its 2.7-inch LCD display with 230,000 dot resolution (translating to roughly 320 x 240 pixels, with three dots per color). Unlike the K2000, however, the Pentax K-x offers a Live View mode which operates on data streamed from the image sensor, enabling images to be framed on the LCD display.
Autofocus. The Pentax K-x uses an 11-point SAFOX VIII phase-detection autofocus sensor, which offers nine cross-type points. The same autofocus sensor has featured in quite a few of the company's digital SLRs since it launched in 2003's *ist D, Pentax's first digital SLR. Indeed, the flagship K-7 still uses a similar sensor, although it supplements it with a dedicated AF assist lamp and a secondary light color sensor, as well as refined AF algorithms. It's a significant upgrade from the five-area AF system of the K2000. As we mentioned, though, there are no AF in-focus indicators in the optical viewfinder to show which AF point or points are selected.
Live View. In addition to phase-detection AF, the Pentax Kx offers contrast detection autofocus with face detection capability when used in Live View mode. Like the K2000 before it, the Pentax Kx performs exposure metering with a 16-segment sensor, although the sensitivity range of EV1 to 21.5 (ISO 200 with a 50mm F1.4 lens) differs slightly from the EV0 to 21 range quoted for the predecessor camera.
Exposure. The Pentax K-x offers quite a selection of exposure modes, with varying degrees of control from fully automatic to fully manual shooting. The Mode dial on the Pentax K-x's top panel provides direct access to the camera's Program and full Manual modes, as well as three Priority modes which allow the user to control either Aperture, Shutter Speed, or Sensitivity while leaving the remaining variables under automatic control.
Six Picture modes merit their own positions on the Mode dial for ease of access, including Portrait, Landscape, Macro, Action, Night Scene Portrait, and Standard Flash Off modes. Also found on the Mode dial are one position each for the Scene, Auto Picture, and Movie modes (more on this last choice in a moment). When set to Auto Picture mode, the camera automatically selects between the same six Picture modes just mentioned. The Scene position, meanwhile, allows one of ten modes to be selected on the camera's LCD display: either Night Scene, Surf & Snow, Food, Sunset, Kids, Pet, Candlelight, Museum, Stage Lighting, or Night Snap. Both the Stage Lighting and Night Snap modes only allow images to be saved as JPEG files.
Shutter speeds on offer in the Pentax Kx range from 1/6,000 to 30 seconds plus a bulb mode, and impressively for an affordable camera, Pentax is rating the K-x's shutter mechanism as good for around 100,000 shots. Most digital SLRs at this price range max out at 1/4,000 second, and none spec an approximate shutter life.
Fast burst rate. Another impressive capability of the Pentax K-x is its burst shooting mode. With the company's flagship Pentax K-7 capable of shooting at 5.2 frames per second, the full-res 4.6 fps offered by the Kx really isn't a whole lot slower. When shooting at this maximum rate, burst depth is limited to five RAW or 17 JPEG frames. (We measured 4.32 fps for 25 JPEGs and 4.55 fps for 5 RAW frames.)
White balance. The Pentax K-x determines white balance using its image sensor, and offers both Automatic and Manual modes, plus ten presets including the new Color Temperature Enhancement mode introduced in the K-7, which is used to retain and enhance the lighting tone -- for example, to enhance a sunset.
Creative modes. The Pentax Kx also offers a range of functionality for photographers looking to unleash their creative side without the need for a PC. The High Dynamic Range shooting mode which debuted in the K-7 makes a repeat appearance, allowing several bracketed exposures to be combined in-camera to form a single image with increased dynamic range. When the K-7 was launched, Pentax was unique in providing this feature in a DSLR, but Sony has since included a similar function in its A500 and A550 models. Each company's approach has advantages and disadvantages in operation.
|Three additional colors are available, with the Navy option looking less outrageous than the red or white.|
Pentax's HDR mode captures three bracketed images, allowing a greater dynamic range to be covered with its mode, where Sony captures just two source images. In turn, though, Sony's HDR mode takes significantly less time to process, and yet is capable of micro-aligning images to allow for handheld shooting, where Pentax's mode requires use of a tripod. (In both cases, a relatively static subject is needed to prevent artifacts in the final image).
In addition to HDR photography, the Pentax Kx allows in-camera processing of RAW files, and as with the K-7 it also offers a wide range of digital filter and custom image modes that give the photographer a significant amount of control over the final look of images. One function newly added since the K-7 is Pentax's Cross Process mode, which is intended to offer a similar effect to the film processing technique. Cross processing of film involves intentionally using processing chemicals with a film type for which they weren't intended, with unpredictable but sometimes eyecatching effect. The Cross Process filter in the Pentax K-x makes quasi-random changes to an image, with the final effect unknown until it is shown on the camera's display.
Movie mode. The Pentax K-x also offers the ability to shoot high-definition movies, much like the K-7 before it. The main differences are that the K-7's non-standard maximum resolution of 1,536 x 1,024 pixels and its external microphone jack have both been dropped, and the frame rate reduced slightly from 30 to 24 fps. Otherwise, the mode is quite similar, with videos recorded at resolutions of either 1,280 x 720 (16:9 aspect ratio) or 640 x 416 (approx. 3:2 aspect ratio), and then saved as AVI files using Motion JPEG compression.
Note that there's no high definition video connectivity on the Pentax K-x, so movies must be offloaded from the camera before they can be viewed in their full high-def glory.
Storage and battery. The Pentax Kx stores its images and movies on Secure Digital cards, including the larger and faster SDHC types. Still images can be saved as JPEG compressed or RAW files, with the K-x supporting both Pentax's proprietary .PEF and Adobe's .DNG RAW file formats.
Power comes courtesy of four AA batteries, with both alkaline / lithium disposables and NiMH rechargeables listed as being compatible. Battery life using the optical viewfinder is rated as 1,100 shots using lithium disposable batteries, to CIPA testing standards which include 50% flash usage. That drops to only 420 shots with NiMH rechargeables, which is below average for an SLR. Both NTSC / PAL standard-definition video output and USB 2.0 High Speed computer connectivity are included.
Shooting with the Pentax K-x
by Mike Tomkins
Having recently purchased Pentax's K-7 prosumer digital SLR myself, and spent the last couple of months growing familiar with its interface, I found the K-x to be a very comfortable camera to use overall. Much of its UI mirrors that of its higher-end sibling. I did miss having a second control dial, but that's to be expected in an entry-level camera, and you get used to it quickly. My first impression on handling the Pentax K-x was one of mild surprise at its heft, though. It's a fair bit smaller than the K-7, which is already fairly compact by DSLR standards. With batteries loaded and ready to shoot, however, the Pentax K-x wasn't as light as its dimensions might suggest. Using four Sanyo Eneloop (HR-3UTG; 2,000 mAh) AA batteries, body weight with no lens attached was approximately 22 ounces, only 4.5 ounces less than the K-7. By comparison, several of the Pentax K-x's nearest rivals from Canon, Nikon and Sony come in at around the 18-19 ounce mark without a lens, thanks to their use of rechargeable lithium-ion batteries.
None of this is to say that I found the K-x to be unwieldy; on the contrary, its weight was nicely balanced, and it fit comfortably even in my rather large hands. The Pentax K-x's body also felt reassuringly solid and sturdy for an entry-level camera, with little flex or creak in its fiber-reinforced polycarbonate panels, which are constructed around a stainless steel chassis.
Lens variety. Some of the K-x's heft is also cancelled out by the availability of several kit lens options which include the Pentax DA-L 18-55mm F3.5-5.6 AL lens, and in the two-lens kits, either the Pentax DA-L 50-200mm F4-5.6 ED or DA-L 55-300mm F4-5.8 ED lens. These lenses are optically identical to their standard DA equivalents, but somewhat lighter thanks to a few tweaks. The changes include the removal of the quick-shift feature (which allows focus to be manually adjusted after an autofocus operation on a DA lens without first changing the focus mode), and the use of a plastic lens mount rather than a metal one. Personally, I could live without the quick-shift AF function to save a little weight and cost, as I don't find myself using it that often.
My review kit included the DA-L 18-55mm lens, which I own in its DA WR weather-resistant version, and I found build and image quality to be pretty similar; certainly within what I'd expect for normal sample variation. I've not had the opportunity to try the other two DA-L lenses, but I also own the WR version of the 50-200mm lens and can definitely recommend it as an affordable, yet capable design.
Batteries. I have a feeling that a large part of the weight difference between the K-x and its nearest rivals comes down to its choice of batteries (and to some extent, my own choice of Sanyo's Eneloops, which I favor for their battery life and charge retention, but which aren't necessarily the lightest option). Pentax's K-x is the only current digital SLR that's powered by AA batteries, with all of its rivals having opted for proprietary lithium-ion rechargeables. Certain models -- including Pentax's own K-7 -- can accept AA batteries through the use of a portrait / battery grip, but this is very much a compromise, as the grip itself brings a significant increase in overall size and weight. If you prefer to avoid proprietary batteries, the Pentax K-x is your only choice.
The reasons I tend to favor proprietary lithium ion batteries are twofold: for their greater energy density (meaning less weight for equal battery life), and because in a rush (or in poor light) I find it significantly quicker to change one lithium ion cell than to fiddle with changing four AA cells, all the while paying attention to the orientation of each cell. I should note that I did occasionally experience two issues with my review K-x reporting low charge remaining on my freshly charged, brand-new Eneloops (even if the battery type was specified through the menu system), and with the camera simply refusing to power on after a change to fresh batteries. In each case, reseating the batteries or simply opening and closing the battery compartment door was enough to clear the issue. We had the same trouble in the lab. Updating the firmware to version 1.01 solved the issue. You can download the firmware update here.)
Continuous mode. Probably my favorite feature of the Pentax K-x is its burst shooting speed. With a burst rate of 4.7 frames per second for as many as five RAW or 17 JPEG frames (we measured a bit slower), the Pentax K-x is one of the fastest cameras in its class, and even nips at the heels of its prosumer sibling, the 5.2 fps Pentax K-7. My own shooting style is such that I tend to favor burst shooting not only for sports, but also in situations like shooting kids and pets. For example, while shooting with the K-x at my son's first birthday party in a dimly lit pizzeria, I could rattle off a burst of shots and then save the best ones. This both saved me having to trust the shot to my occasionally rather dubious reflexes, and ensured that with a large quantity of photos to choose from, I'd still have plenty of keepers despite lighting conditions that made focusing and framing more of a challenge.
High ISO. Equally useful in the same setting was the 12.4-megapixel Pentax K-x's high ISO capability, which noticeably outshines that of the more expensive Pentax K-7. In general usage, I find the K-7's 14.6-megapixel sensor to be too noisy above ISO 3,200, and tend to reserve higher sensitivities for when there's no alternative. See the samples below.
With the Pentax K-x, I found I could get acceptable results at ISO 6,400, especially if shooting RAW and applying some noise processing in Photoshop. At lower sensitivities, what noise is apparent isn't really any more obtrusive than film grain, and I found myself using ISO 3,200 with surprising regularity during my time with the Pentax K-x. Having a usable high sensitivity is great for avoiding the use of flash, and yields much more natural looking shots.
Confirmation? The only thing that really stood out to me as a particular annoyance with the Pentax K-x is something we've mentioned several times elsewhere in this review, but it's something that bears repeating. Going into this review, I was aware that the Pentax K-x lacked any indication of autofocus point location or selection in the optical viewfinder, but I must admit I thought I'd get used to it and work around it quickly and easily. In actuality, the longer that I used the Pentax K-x, the more I found this design decision bothered me. With the Pentax K-x offering a smaller, dimmer pentamirror viewfinder than the K-7, I found it wasn't as easy to determine the exact focus point in low light.
Shooting at my son's birthday party was one example of conditions in which I'd have to give up on the Pentax K-x's 11-point AF system, solely due to the lack of a viewfinder indication. The problem was that with no indication of the active focus point, I wouldn't catch that the K-x had decided to set focus in the wrong place. Setting the focus point manually was too slow, however, requiring me to take the camera away from my eye each time I wanted to change the active point. Hence, I'd end up just using the central point to lock focus with a half-press of the shutter button, then recompose the shot and trigger the shutter. For burst shooting, I'd prefocus on my subject's eyes and then trigger a burst of shots with AF disabled. A large proportion of the shots where I got lazy, letting the camera determine the focus point for me instead, ended up having to be discarded because focus was set in the wrong place.
This is all particularly disappointing because I found the Pentax K-x's autofocus system perfectly capable of locking focus correctly in pretty low-light; certainly, as dim as I'd be capable of shooting handheld without flash. That's not surprising, because the Pentax K-x uses basically the same AF sensor as the K-7, albeit without the extra sensor used to determine and account for color temperature of the light source when focusing. With eleven points, all but two of these being cross-type points, the K-x's AF system is fairly sophisticated for an entry-level camera at its price point. Hopefully, Pentax will see fit to add AF point illumination in the K-x's successor, because it would make this AF system significantly more usable (and hence, useful).
Sensor movement? We've seen some talk in photography forums about shutter-induced blur with some Pentax Kx units when shooting around 1/100 second with SR on, and mostly vertical, but we haven't noticed any examples among our images captured during our review, as we did with the Olympus E-P1. So we took some informal shots to see if we could reproduce the error with handheld shots. We saw the image-doubling issue in about one out of ten shots at 1/100 second. Our best example was captured in horizontal orientation, though, not vertical as we'd expected. Look closely and you can see that all the horizontal lines have a slight ghost image a few pixels down in this 100 percent crop. Might the sensor be shaking in response to the vibration of the shutter or mirror mechanism? Or perhaps the SR system is responding to the vibration. The third and fourth possibilities are movement of a lens element or photographer movement. These were captured with the 43mm Limited lens, which in our experience is rock solid, so that's probably not it. It could also be photographer motion, but the shift seems more of a distinct, mechanical movement, not as much a blur. At least in our unit, it's not a large issue, as we didn't notice it in any of our test or Gallery shots; then again, it didn't take much to reproduce the phenomenon. We'll leave it to you to decide whether it's an important issue for you. All SR systems smear at some point, but we'd prefer it didn't happen at 1/100 second with a 43mm lens.
Pentax Kx Print Quality
The Pentax K-x's printed output is really impressive, able to make usable 20 x 30-inch prints at ISO 100, straight from the camera with standard noise suppression on. They're slightly soft in some places, tack sharp in others; a little sharpening in a program like Photoshop could make them even better. 16 x 20 images are about the same, with a little more sharpness than the 20 x 30-inch prints. The amazing part is that print quality remains this good up to ISO 800! Even our troublesome red swatch still looks better than most cameras do at ISO 800, even when printed at 16 x 20.
ISO 1,600 represents the first break from this remarkable print size, and it's also the first time the red fabric swatch begins to decay. Still, the rest of the detail looks fabulous, with just a little noise and noise suppression artifacts creeping in. Reduction to 13x19 at this size is a little better.
ISO 3,200 shots also look decent printed at 13x19 inches.
ISO 6,400 shots are generally usable at 11x14, remarkably, but of course better at 8x10.
Depending on the subject ISO 12,800 shots are usable at 8x10, though contrast is increased and there's some blotchy noise in the shadows. At 5x7 inches, though, no one will notice.
A truly excellent and surprising outcome from the Pentax Kx!
Pentax Kx Image Quality
Pentax Kx vs Pentax K7 at ISO 1,600
Pentax Kx vs Canon T1i at ISO 1,600
Canon T1i at ISO 1,600
Easily the Pentax Kx's greatest rival is the 15.1-megapixel Canon T1i, yet I think the Kx holds up quite well despite the difference in resolution.
Pentax Kx vs Nikon D5000 at ISO 1,600
See below for Pro/Con listing and Conclusion.
In the Box
The Pentax Kx comes with the following items in the box:
- Pentax Kx body
- Body mount cover
- 18-55mm lens (Kit version)
- Front and back lens caps
- USB cable
- Hot shoe cover
- Four AA lithium batteries
- Software CD ROM
- Operating manual
- Registration kit
Pentax K-x Conclusion
As I packed up my K-x review unit, I found myself in two minds as to whether I'd consider buying the camera myself. On the one hand, I could see it being a very useful second body to accompany my K-7 for low-light, high ISO shooting. On the flip side of the coin, for my shooting style I think the lack of AF point illumination would be hard for me to live with, and I'd prefer a lithium-ion-based camera with two control dials. Pentax's current DSLR lineup consists of just two models, but were they to offer an intermediate DSLR based on the K-x, with these three design points altered to my tastes, I'd very likely pick it up as a second body to accompany my K-7. If you can live with the lack of AF point illumination, though, there's no denying that the K-x offers a lot of camera for the money. The Pentax Kx can take some mighty fine pictures, and offers compatibility with some truly lustworthy Pentax glass, including their flagship DA Limited lenses. The bottom line is that I'm not the target customer for the K-x. Regardless, the Pentax Kx has enormous value, thanks to its remarkable image and print quality, fine build, and class-leading burst speed, all combining to make one impressive digital SLR camera. The Pentax Kx is a Dave's Pick, with the warning that there are no AF indicators in the viewfinder. But for sheer image quality at a wide range of ISOs, the Pentax Kx is tough to beat, especially for the price.