Originally Posted: March 5, 2010
Last Updated: February 13, 2011
The Pentax K-x (from $649) is an entry-level digital SLR that doesn't skimp on features. It features a 12.4 Megapixel CMOS sensor, a compact, well designed body, full manual controls (plus an auto scene recognition mode), fast continuous shooting, live view, 720p video recording, and more. And, unlike most D-SLRs, the K-x uses AA batteries (and gets great battery life, to boot).
The K-x has some tough competitors, including the Canon EOS Rebel XS, Nikon D5000, Olympus E-620, Panasonic Lumix DMC-G1, Samsung NX10 (coming soon) and the Sony Alpha DSLR-A380. How does it fare against those cameras? Find out now in our review!
What's in the Box?
The K-x is sold in a variety of kits and colors, though you won't find a body-only kit. The camera and 18 - 55 mm lens kit ($649) comes in black, white, navy blue, and a red that will certainly get you noticed. If you want more than one lens, it'll be black only. The dual lens kits include the 18-55 and either a 50-200 ($749) or 55-300 ($849) lens in addition. Here's what you'll find in the box for each of those:
- The 12.4 effective Megapixel Pentax K-x camera body
- F3.5-5.6, 18 - 55 mm Pentax D-AL lens
- F4.0-5.6, 50 - 200 mm Pentax D-AL lens [50-200 kit only]
- F4.0-5.8, 55 - 300 mm Pentax DA lens [55-300 kit only]
- Four AA lithium batteries
- Body cap
- Shoulder strap
- USB cable
- CD-ROM featuring Pentax Digital Camera Utility 4
- 315 page manual (printed)
Whichever kit you buy, it includes a lens, so you can start taking pictures right away. The main kit lens is a lower cost version of the F3.5-5.6, 18 - 55 mm lens that's been around for a while. Pentax swapped the metal lens mount on the retail lens (which also version 2, this one is version 1) with a plastic one here, to keep costs down. While not spectacular, it's a decent kit lens, with good sharpness (though it falls off toward the sides of the frame), relatively little barrel distortion, and (usually) low levels of purple fringing. If you want to use another Pentax lens, there are plenty to choose from, whether they're brand new or decades old (though old lenses may require an adapter). Whichever lens you use, you'll have a 1.5X focal length conversion factor to keep in the back of your mind.
As with all D-SLRs, Pentax does not include a memory card in the box with the K-x. So, unless you already have one, you're going to need to pick up an SD or SDHC memory card right away. I'd recommend a 2GB or 4GB card to start with, and it's worth getting a card rated as "Class 4" or higher for best performance.
The K-x is one of very few digital SLRs that use AA batteries for power. I, for one, happen to like this, as they're cheaper than their proprietary counterparts, and you can easily get them in an emergency. I'd recommend picking up a set or two of NiMH rechargeable batteries (2500 mAh or higher) which will save you money in the long run (and help the environment while you're at it). Here's what kind of battery life you can expect from the K-x and its competitors:
Pentax isn't doing themselves any favors by testing the camera with anemic 1900 mAh batteries! I figure that you can take at least 550 shots per charge using more powerful 2500 mAh batteries. At that point, the K-x beats all of its competitors. If you use non-rechargeable lithium batteries, you can take a whopping 1100 shots per charge. While you can use alkalines, you can only take around 130 shots per charge.
Pentax doesn't publish live view battery life numbers for the K-x, but it's safe to say that it's at least half of what you see above.
Pentax does not offer a battery grip for the K-x.
Being a digital SLR, you shouldn't be surprised to hear that there are plenty of accessories available for the K-x. Here are the most interesting ones:
Notice how the A/V cable is included in that table -- Pentax doesn't include one in the box, I guess to keep the price of the camera down. There are a couple of other things available, including various viewfinder accessories and camera cases.
Pentax Digital Camera Utility 4 for Mac
Pentax includes a single software product with the K-x, and that's their Digital Camera Utility version 4. This software -- for Mac and Windows -- is based on SilkyPix, which is often bundled with many other RAW-capable cameras. Thankfully, the interface in the Pentax Utility is a lot cleaner than in regular SilkyPix, though it's a bit sluggish at times.
This software can be used in a few ways: for acquiring images from your camera, for managing them in a lightbox-style interface, and for performing some pretty heavy-duty edits (for RAW images, specifically). The editing tools are quite powerful, and can be used for both JPEG and RAW images. Here are some of the things that you can do:
- Crop, rotate and "shift" an image
- Change the Custom Image setting (more on this later)
- Adjust and fine-tune white balance
- Adjust exposure and image tone
- Select amount and type of noise reduction applied
- Correction for distortion and chromatic aberration
- Adjust coloring of highlight areas
- Expand dynamic range
- Fine-tune color in a given range
In other words, this software covers just about anything you can possibility imagine. I should also add that Pentax Utility supports batch processing, and the whole user interface is quite customizable.
If you want to use Photoshop CS4 or a recent version of Photoshop Elements to work with the K-x's RAW files, you'll just need version 5.6 or newer of the Camera Raw plug-in.
What's the deal with RAW images anyway? These files contain unprocessed data straight from the camera's sensor. The benefit of this is that you can tweak many camera settings (white balance, exposure, color) without reducing the quality of the image. It's almost like getting a second chance to take a photo. The downsides are the need to post-process the images on your computer, and the huge file sizes, which reduce camera performance and quickly fill up your memory card. The K-x is somewhat unique in that it supports two RAW formats. You can use Pentax's own PEF format, or Adobe's open standard known as DNG (digital negative).
While it's not perfect, the manual that comes with the K-x is definitely better than average. It's thick, detailed, and has good explanations of everything, without too much fine print. As for documentation for the Pentax Digital Camera Utility software: it'll be installed onto your computer.
Look and Feel
The K-x is a compact digital SLR with a plastic outer shell and a stainless steel chassis inside. Despite the plastic shell, the body feels quite solid, especially given the price of the camera. I found the camera comfortable to hold, thanks to a good-sized, rubberized right hand grip. Pentax has done a good job at keeping buttons to a relative minimum. All of the buttons are large, well-labeled, and usually serve just one function. It was nice to see that the K-x still has a control dial -- many of its competitors do not.
Pick your color...
Images courtesy of Pentax
Pentax sells the K-x in some pretty bold colors, to say the least. If you want something conservative, stick with black or navy. Fans of Star Wars may like the white model, while those who really want to stand out in a crowd may gravitate toward the red model.
Alright, now let's see how the Pentax K-x compares to other cameras in its class in terms of size and weight:
If you ignore the two mirrorless (and therefore much smaller) cameras from Panasonic and Samsung, you'll find the the Pentax K-x is quite average in terms of size, and a little heavier in the weight department. It's certainly not a bulky camera. but don't expect to by carrying it around in your jacket pocket, either.
Ready to tour the K-x now? I know I am, so let's begin!
Here's the front of the K-x, without a lens attached. The camera supports all Pentax K-mount lenses, plus old screw-mount and 645/67 medium format lenses (though an adapter is required for those). All but the oldest lenses should support autofocus, and most will work with the camera's image stabilizer right out of the box. The more modern DA, DA L, and D FA lenses support automatic aberration and distortion correction, as well. To release a lens, simply press the button to the lower-left of the mount.
As I just hinted at, the K-x has a sensor-shift image stabilization system, like all Pentax D-SLRs. The camera detects the tiny movements of your hands that can blur your photos, especially in low light, or when using a telephoto lens. The K-x physically moves the sensor to compensate for this motion. Pentax says that the IS system opens up 4 stops of shutter speeds that you couldn't use otherwise. Want to see the IS system in action? Here, have a look:
Image stabilization off
Image stabilization on
I took both of the above photos at 1/5 of a second, which is pretty slow. As you can see, the image stabilizer does its job well, producing a noticeably sharper image. You can also use the K-x's image stabilizer to smooth out your videos, though the system makes quite a bit of noise, which may be picked up by the camera's microphone. Here's an example of how the shake reduction system smoothes out your videos. I left the sound track in this sample movie so you can hear the noise generated by the IS system.
The camera also uses the shake reduction system to remove dust from the sensor, though this feature is not turned on by default. When you do turn it on, the camera will shake the sensor rapidly when it's powered on, and you can also run the system manually at any time.
Directly above the lens mount is the K-x's pop-up flash, which is released electronically. This flash has the typical guide number of 12 meters at ISO 100. Should you want more flash power, you can attach an external flash to the hot shoe that you'll see in a moment, or cut the cord entirely and go wireless, using the built-in flash as the master.
Over on the grip you can see the receiver for the optional wireless remote control, which has the self-timer lamp right next door. If you're wondering about an AF-assist lamp, the K-x uses its built-in flash for that purpose. It's can be quite blinding to people and animals, but it does allow the camera to focus in very low lighting.
The first thing to see on the back of the K-x is its 2.7" LCD display. The screen has a resolution of 230,000 pixels though, to be honest, it didn't seem that sharp in reality. I found the screen fairly easy to see outdoors, though its viewing angle leaves something to be desired.
|The view in live view mode||Zoomed in 4X in live view mode|
As with all D-SLRs these days, the LCD isn't just used for menus and reviewing photos -- you can also use it for taking photos, too. The "live view" feature on the K-x is pretty standard, but well implemented. You can compose your photo with 100% coverage, preview exposure and white balance, view a histogram and/or grid lines, and enlarge an area of the frame. This last feature lets you zoom into a photo by as much as 10 times and then move around, which allows for very precise manual focusing. One thing I didn't care for was the low light visibility in live view -- the screen doesn't "gain up" very much, so it's very hard to see your subject.
There are three autofocus modes available in live view mode: face detection, contrast detect, and phase difference AF. The first two both use the camera's CMOS sensor for focusing, and the face detection feature is capable of locating up to 16 faces in the frame. You can also move the AF target anywhere in the frame by using the four-way controller. The problem with contrast detect AF on digital SLRs is that it's slow -- very slow. While a compact camera might lock focus in half a second, the K-x can take one, two, or three seconds to do the same thing. In other words, it's not for action shooting. The good news is that Pentax provides phase difference AF as well, which uses the same dedicated autofocus sensor that you'd get when shooting with the viewfinder. The only real differences are that the live view disappears for about a second while the camera focuses, and that face detection is not available. This mode is always the one I choose on cameras that offer it.
Live view is also the place where you'll record movies -- but I'll save that for later.
|Info display, with a virtual four-way controller||Press the Info button again to get to this screen, where you can quickly change camera settings|
When the LCD isn't being used for live view, it can be turned into an information display, which shows the current camera settings. An additional screen (accessed by pressing the Info button) lets you adjust numerous camera settings (see screenshot). These settings include:
- Custom image
- Cross processing
- Digital filters
- HDR capture
- Shake reduction
- AE metering
- AF mode
- Select AF point
- Highlight correction
- Shadow correction
- FIle format
- JPEG recorded pixels
- JPEG quality
- Distortion correction
- Lateral chromatic aberration adjustment
Needless to say, I'll explain all of those in detail when I get to the menu section of this review.
Getting back to the tour now, let's talk about the K-x's optical viewfinder. The viewfinder is one of the few design-related annoyances on the K-x in my opinion. It has nothing to do with the coverage or magnification of the viewfinder, which are 96% and 0.85, respectfully. Rather, it's the fact that the camera does not show the current focus point in the viewfinder, unlike every other D-SLR on the market. There's no way for the user to know what area of the frame the camera locked focus on, unless you're using center-point AF. While I understand that some features need to be removed to keep the price down on a camera, this is one that definitely should not have been cut. At least you still get the line of information under the field-of view, which displays the shutter speed, aperture, focus lock, ISO, and exposure compensation setting (the number of shots remaining is not displayed). You can adjust the focus of the viewfinder by using the diopter correction slider on its top side.
To the left of the viewfinder is a button which releases the built-in flash, and it also is used for deleting photos. On the opposite side you'll find the camera's one and only command dial -- used for adjusting manual settings, navigating menus, and enlarging photos -- and the AE/AF lock button.
Now let's talk about the four buttons located to the right of the LCD. They include:
- Playback mode
- Live view - turns this on and off
- Info - toggles what's shown on the LCD
To the right of those is the four-way controller, used for menu navigation, selecting a focus point, moving through photos you've taken, and also:
- Up - Drive (Single shot, continuous lo/hi, 2 or 12 sec self-timer, 0 or 3 sec remote control, exposure bracketing)
- Down - Flash setting (Flash on, flash on + redeye reduction, slow sync, slow sync + redeye reduction, trailing curtain slow sync, wireless mode) + flash exposure compensation (-2EV to +1EV, 1/3EV increments)
- Left - White balance (Auto, daylight, shade, cloudy, fluorescent x 4, tungsten, flash, color temperature enhancement, manual)
- Right - ISO sensitivity (Auto, 200 - 6400)
- Center - OK + focus point select
There's plenty to talk about before we can continue the tour. Let's start with the drive options, specifically the two continuous shooting choices. There are low and high speed continuous modes, and here's what kind of performance you can expect from the K-x:
While it doesn't have a lot of buffer memory, the K-x does have the fastest burst rate in its class. When you hit the limits I listed in the table above, the camera doesn't stop shooting -- it just slows down considerably. Do note that the live view will shut off after the first shot when shooting continuously, so you'll probably want to track your subject using the optical viewfinder.
The drive menu also contains the camera's AE bracketing feature. With this turned on, the camera will take three photos in a row, each with a different exposure compensation setting. The interval between each of the shots can be as little as 1/3EV, or as much as 3EV.
|Lots of white balance choices||Plus the ability to fine-tune|
Now onto white balance, where the usual presets like tungsten and sunlight are just the beginning. Each of those presets can be tweaked, as you can see above. You can also use a white or gray card for accurate color in mixed or unusual lighting. There's also a unique Color Temperature Enhancement (CTE) option, which Pentax describes as the opposite of auto white balance. For example, if the camera is using a high color temperature, CTE will crank it up a little higher, to emphasize the colors in the scene. So what can't you do? You can't set the color temperature, and there's no WB bracketing feature.
Adjusting the ISO sensitivity
In the ISO menu, you can select a set value, ranging from 200 - 6400, which is expandable to 100 - 12,800. You can also use Auto ISO, which allows you to select the upper limit that the camera will use. We'll see how the K-x performs throughout its ISO range later in the review.
And that's it for the back of the camera!
You may not notice it at first, but the first thing to see on the top of the K-x is its microphone, which is located toward the left side of the photo. The camera records monaural sound, and does not have an input for a stereo microphone.
In the center of the photo is the K-x's hot shoe. As I mentioned earlier, you'll get best results by using a Pentax flash, as they'll sync up with the camera's metering system. The two top-end Pentax flashes (the AF360FGZ and AF540FGZ) also support high speed flash sync, use of their AF-assist lamps, and they can also serve as wireless flash transmitters (as can the built-in flash). If you're using a non-Pentax flash, you may have to set the exposure on both the camera and flash manually. Unless you're using high speed flash sync, the maximum shutter speed you can use with an external flash is 1/180 sec.
Continuing to the right, we find the K-x's mode dial, which is packed with options. Here's the full list:
The K-x has both automatic and manual controls, which should satisfy just about everyone. On the point-and-shoot side, there's the Auto Picture mode, which selects one of six scenes automatically (two more are available when using live view). You can also select a scene mode yourself, with plenty to choose from.
As for manual controls, you've got the usual suspects: program, shutter priority, aperture priority, and full manual. There's also the unique sensitivity priority mode, where you set the ISO and let the camera figure out the rest. The K-x does not have the TAv mode that's found on the more expensive K-7, nor is there a dedicated spot on the dial for your favorite camera settings.
Above the mode dial are the exposure compensation and "green" buttons. The former does just as it sounds, with an available range of -3EV to +3EV. The green button is customizable, and by default it returns the exposure settings to their defaults (I'll list the other options later).
In-between those buttons is a blinding blue power lamp, which thankfully can be dimmed or shut off altogether in the setup menu. Just north of that is the shutter release button, which has the power switch wrapped around it.
There are just two things to point out on this side of the Pentax K-x. The first is the switch between auto and manual focus, with the second being the camera's single I/O port, which is under a rubber cover. This port is for USB and A/V output. The K-x does not have an HDMI port, though I wouldn't really expect one, given its price.
On the other side of the camera you'll find its SD/SDHC memory card slot, which has a plastic door of average quality protecting it.
The only other thing to note here is the tiny flap through which you pass the power cord for the optional AC adapter.
Let's end our tour with a look at the bottom of the K-x. Here you can see the metal tripod mount, which is -- of course -- in line with the lens. The other thing here is the battery compartment, which holds four AA batteries (yay!). The door is fairly sturdy, and includes a locking mechanism.
Using the Pentax K-x
Flip the power switch and the K-x is ready to go almost instantly. If you've chosen to have the noisy dust reduction system run at startup it'll slow things down by about a second, though you can interrupt the process by pressing the shutter release button.
As usual, autofocus speeds depend on a number of factors, including the lens you're using and whether you're using live view. When shooting with the viewfinder, the K-x focuses quickly, though the lack of focus point indicators in the viewfinder is very annoying. Expect wide-angle focusing times between 0.1 and 0.3 seconds, with telephoto times ranging from 0.4 - 0.8 seconds (both with the 18 - 55 mm kit lens). Low light focusing is good, especially with the flash popped up (for AF-assist) -- expect focus times to stay under a second.
Things aren't nearly as nice when you're using live view. If you're using face or contrast detect AF, expect multi-second waits for the camera to lock focus. And forget about low light focusing -- it takes forever, and quite often the camera won't lock. For better results, use phase difference AF, which gives you the same speeds as when shooting with the viewfinder, plus about a second delay while the mirror does its thing. Do note that the AF-assist flash cannot be used when in live view.
As for shutter lag, there won't be any if you're shooting with the viewfinder, or using contrast detect AF in live view. If you're using phase difference AF in live view, there's about a second of lag due to the mirror flipping action.
Shot-to-shot delays are minimal, regardless of the image quality setting or whether you're using the flash.
You can delete a photo right after you take one by pressing the -- get ready -- delete photo button!
Now, here's a look at the available image size and quality choices on the K-x. Like on their point-and-shoot cameras, Pentax uses a star system to rate image quality, with 3 stars being the highest.
As I mentioned earlier, the K-x supports not one, but two RAW formats. You can select from Pentax's PEF or Adobe's DNG format, both of which offer the same benefits of the RAW format that I discussed earlier. The camera allows you to take a RAW image by itself, or along with a JPEG of any size or quality.
One thing that hasn't changed with Pentax's cameras over the years is its menu system. If you went back five years ago and found an Optio camera, odds are that the menu would look a lot like the one on the K-x. That's not to say that the menu system is bad -- rather, it just looks dated, lacks any kind of help system, and could just be a little more user-friendly. The menu is broken down into four main tabs, covering shooting, playback, custom, and setup options. Here's what's available in the K-x's menu:
As you can imagine, there's a lot to talk about before we can move on to our photo tests. Let's start with the Custom Image feature:
|All the Custom Image sets||Tweaking the sharpness of the "bright" set|
A Custom Image "set" contains various exposure and color settings, and there are seven presets available: bright (default), natural, portrait, landscape, vibrant, muted, and monochrome. There aren't any custom sets, though -- you have to modify one of the presets. For each of these you can adjust the following:
- Saturation (-4 to +4)
- Hue (-4 to +4)
- Brightness [high/low key] (-4 to +4)
- Contrast (-4 to +4)
- Sharpness (-4 to +4) - a "fine" sharpness option is also available
- Filter effect (None, green, yellow, orange, red, magenta, blue, cyan, infrared) - for monochrome modes only
- Toning (-4 to +4) - lower numbers are "cold", higher numbers are "warm"
You can get a preview of the Custom Image settings by pressing the exposure compensation button, which takes a quick photo that is not saved to the memory card (by default).
The K-x has two dynamic range settings: highlight correction and shadow correction. Highlight correction is something that is turned on or off (it's off by default). It boosts the ISO to a minimum of 400 (it will use ISO 200 if ISO expansion is on), and then does its stuff. Shadow correction can be turned off (which is the default) or set to low, medium, or high.
|Highlight correction on
View Full Size Image
The highlight correction feature definitely improves highlight detail -- just look at the columns over on the right side of the photo. The bad news is that shadow detail really gets sacrificed in the process. Of course, you can also turn shadow correction on too, though I didn't get a chance to try that.
|Shadow correction off
View Full Size Image
|Shadow correction low
View Full Size Image
|Shadow correction med
View Full Size Image
|Shadow correction high
View Full Size Image
If I could describe this feature in one word, it would be "subtle". The trees get a bit brighter, but don't expect massive amounts of brightness to suddenly appear.
Next up is Cross Processing, which is a technique that dates back to the film days. In those days, cross processing meant that you used the wrong chemicals when developing your film, to get photos that look a lot different than expected. Now it's a digital effect, and there are four modes to choose from (if you only have on or off, then you need to update your K-x's firmware). Pentax doesn't actually specify which each of the options does, so I'll just show you:
|Cross Processing off||Standard CP||Cross processing 1||Cross processing 2||Cross processing 3|
Pretty freaky if you ask me! The K-x has numerous digital filters that can be applied to images, either as you take them, or later in playback mode. You can even combine several of these filters into a new custom one, if you really want to go crazy.
Lens correction is another neat trick the K-x can pull off. Some cameras, notably from Panasonic, already apply distortion and chromatic aberration correction to photos you're taking, and those are both optional here. You can correct for lens distortion (both barrel and pincushion) as well as lateral chromatic aberration. You'll find an example of the barrel distortion correction in action a little further down the page, in the photo test section. Here's a crop showing the chromatic aberration correction at work:
|Chromatic abberration correction off||Chromatic aberration correction on|
This as you may recognize is a crop from the "purple fringing tunnel of doom" at Stanford, that's included in every photo gallery on this site. This hallway is guaranteed to bring out the worst purple fringing in a camera, and it definitely does so here. And, look at that -- the CA correction feature did a pretty good job of reducing the amount of purple fringing AND highlight clipping in the photo. Do note that both distortion and lateral CA correction require some extra processing time after you take a photo. In addition, these features only work with modern DA, DA *, and DA L lenses.
The HDR Capture feature takes three exposures in rapid succession and combines them into a single image with high dynamic range. One image is underexposed, another is overexposed, and the third is of normal exposure. Since the images need to be precisely aligned, a tripod is essentially required for this feature. You can apply "standard" or "strong" HDR enhancement to a photo. Here's what this feature can do for you:
View Full Size Image
View Full Size Image
View Full Size Image
There's no doubt that dynamic range is improved when using the HDR feature. That said, the resulting photos have that sort of washed out, surreal appearance that can be a trademark of HDR images. Do note that you can't take RAW images in HDR mode, and that the image stabilizer is turned off as well.
The multi-exposure feature lets you combine anywhere from two to nine exposures into a single image. You can choose to have the camera adjust the exposure (gain) automatically, if you'd like. The K-x doesn't have the time-lapse (interval shooting) mode of the more expensive K-7.
And what are those AF modes all about? AF-S locks the focus when you halfway-press the shutter release button. In continuous AF (AF-C) mode, the camera will keep focusing, even with the shutter release pressed -- great for moving subjects. The default setting, AF-A, automatically selects one of those two modes based on what's going on in the scene.
The last thing related to menus that I wanted to say is that the K-x has a rather large number of custom functions for a camera in this class. Many folks may not use them, but it's nice to know that they're available!
Alright, that's all for menus (phew) -- let's move onto photo quality now. With the exception of the night scene (which was taken with the F4.0-5.6, 50 - 200 mm lens), all of these test shots were taken with the 18 - 55 mm kit lens.
The Pentax K-x did a very nice job with our macro test subject. The colors look good, and the subject is quite sharp, especially for a digital SLR, whose images are often soft out of the box (I imagine that Pentax tweaked the sharpness to make the K-x more consumer-friendly). You can easily count the specs of dust on the figurine. The only issue I really have (and this is something that I encountered throughout my tests) is that it's hard to get accurate exposure if you rely on exposure compensation. The subjects were either too dark (see the studio ISO test later), or too bright (as in this case).
The minimum focus distance to your subject depends on what lens you're using. For the 18-55 kit lens, it's 25 cm. If you think you'll be doing a lot of macro photography, Pentax has four lenses for just that purpose, with focal lengths ranging from 35 mm to 100 mm.
The night shot is just "okay", and I think that's mostly due to the rather unimpressive 50 - 200 mm lens that Pentax sent along with the camera. The image is a bit on the soft side, with strong purple fringing. Put on a more impressive piece of glass, such as this guy, and I imagine you'd get a much sharper photo with very little purple fringing. There's also a considerable amount of highlight clipping, which is something that the K-x has some issues with. Still, the camera does capture a lot of detail, and there's no noise to be found here. And, as you'd expect, bringing in enough light is a piece of cake, thanks to the full suite of manual exposure controls on the K-x.
Alright, let's use that same scene to see how the K-x performs at its various ISO settings. I've opened up the full ISO range here (using the ISO expansion custom function), so now we're starting at ISO 100 and going all the way up to 12,800. I apologize for some minor inconsistencies in exposure between these photos -- turns out that the K-x and my Eye-Fi Pro card don't get along too well!
ISO 100 (requires ISO expansion to be on)
ISO 12800 (requires ISO expansion to be on)
The photos taken at ISO 100 through ISO 400 are all very clean. You start to see some increase in noise at ISO 800, but it's not nearly enough to concern me. The ISO 1600 shot came out darker than I wanted (though look for the DNG conversion below, which is okay), but you can still see that there's a bit more noise present, though it's still very usable for small and midsize prints. Detail loss becomes a lot more noticeable at ISO 3200, so now's a good time to start thinking about shooting RAW, or just sticking to small prints. I'd probably pass on ISO 6400, and definitely ISO 12,800.
Now let's see what the benefit of shooting RAW and doing some simple post-processing can do to improve your high ISO photos. There's a difference in exposure between the ISO 1600 JPEG and RAW conversion, since the JPEG at that shutter speed was corrupted.
There's no doubt that you can get photos with more detail and less noise by shooting in the RAW format and using some noise reduction and sharpening filters -- up to a point. The improvement is quite noticeable at ISO 1600 and 3200, but not so much at ISO 6400, so I'd still probably avoid that sensitivity unless you're really desperate.
I was surprised to see some mild redeye on this digital SLR. Usually, since the flash pops up well away from the lens, redeye will not be a problem, but that's not the case here. And, for those who are wondering, I used the redeye reduction flash setting when I took this shot. Unfortunately, the K-x does not have a redeye removal tool in playback mode, so if you encounter this annoyance, you'll have to fix it on your computer.
Distortion correction off
Distortion correction on
The first distortion test chart you see above was taken with the 18 - 55 mm lens with the camera at its default settings. As you can see, there's some noticeable distortion, plus some vignetting as well (which wasn't a problem in my real world photos). When you turn on the distortion correction feature, things look a lot better -- look at how much straighter the lines are now. While blurring corners weren't an issue with this lens, things did seem sharper in the center of the frame than they did toward the edges.
Now it's time for our normal lighting ISO test, which is taken in our studio. Since the lighting never changes, this test can be compared to other cameras I've reviewed over the years. This image turned out a bit darker than I would've liked, but adjusting the exposure a bit higher make it too bright. And remember, While the crops below give you a quick idea as to the amount of noise at each ISO sensitivity, viewing the full size images is always a good idea. And with that, here we go:
ISO 100 (only available with ISO expansion on)
ISO 12800 (only available with ISO expansion turned on)
Everything looks really clean though ISO 800, with minimal noise, found mainly in the shadows. There's a very slight increase in noise at ISO 1600, but it won't stop you from making large prints at this sensitivity. You start seeing some detail smudging at ISO 3200, which reduces your print sizes a bit, but it's still usable, especially with a little post-processing. ISO 6400 really isn't that bad, and could be used for small prints without any retouching. That said, a trip through Photoshop will give you even better results, as you'll see in a moment. I'd probably pass on the ISO 12,800 setting, which has too much detail loss to be usable.
Let's take the ISO 3200 and 6400 images and do some really easy post-processing on them. These were taken in the RAW (DNG) format, converted with Photoshop, and run through the NeatImage (noise reduction) and Unsharp Mask filters.
JPEG, straight out of the camera
RAW -> JPEG conversion (ACR)
RAW -> JPEG conversion + NeatImage + Unsharp Mask
JPEG, straight out of the camera
RAW -> JPEG conversion (ACR)
RAW -> JPEG conversion + NeatImage + Unsharp Mask
There's actually very little difference between the JPEG and retouched RAW images as ISO 3200, which tells me that Pentax's JPEG algorithms are pretty solid. Post-processing in Photoshop does make a more noticeable difference at ISO 6400, so I'd recommend spending the extra time to do that for your super-high sensitivity photos.
Overall, the Pentax K-x's photo quality was very good, though there's some room for improvement. The issues I have are mainly related to exposure. In many of my real world photos, the camera underexposed by 1/3 to 2/3 of a stop (though the reverse was true on one or two occasions). The K-x also clips highlights a bit more than I'd like. On a more positive note, colors are spot-on, and images are much sharper than your typical D-SLR (though photos are a bit soft toward the edges of the frame). I did notice some jaggies in some of my photos, which could be from the heavy sharpening the K-x is applying to its photos. The K-x does a nice job of keeping noise and noise reduction under control, until you reach the highest ISO settings. You will see some grainy noise in areas of low contrast (the sky being one example), but that won't be noticeable unless you're viewing the photos at 100% on your computer screen. Purple fringing is mostly a lens issue, and I found it to be moderate at times with the 18 - 55 mm kit lens.
Don't take my word for all this -- have a look at our extensive photo gallery and judge the K-x's image quality with your own eyes!
The K-x features a high definition 720p movie mode. You can record videos at 1280 x 720 (24 fps) with monaural sound for up to 25 minutes or 4GB (whichever comes first). At the highest quality setting (***), you'll hit the file size limit in a little over eleven minutes. Thankfully, Pentax gives you three quality levels to choose from, so you can take longer movies if you wish. A lower resolution is also available -- 640 x 416, to be exact.
When you're recording movies, the image stabilizer is active, but it makes a lot of noise, and will likely be picked up by the microphone (watch the shake reduction sample video to see what I mean). You can zoom in and out to your heart's content, but the camera will not be continuously focusing. If you're in AF-S mode, you can hit the AF button to have the camera focus again, or you can just do it manually. The K-x can adjust the aperture automatically (to keep brightness consistent), or it can be fixed throughout the recording.
Movies are saved in AVI format, using the "dmb1" codec. File sizes are quite large, courtesy of a nearly 40 Mbps bit rate. Our sample movie, which is less than 10 seconds, is almost 49MB. The quality looks pretty good to my eyes, though the 24 fps frame rate seems more choppy than cinematic.
Here's a sample video for you, taken at the highest quality setting. I've got the huge 48MB original for you, or a recompressed QuickTime version whose colors don't look quite as nice.
While they're not visible immediately, the K-x actually has a nice set of playback mode features. The basics are all here, including slide shows, DPOF print marking, image protection, thumbnail view, and playback zoom. This last option lets you blow up the image by as much as 16X, and you can then scroll around to check for proper focus, closed eyes, etc. A "quick zoom" option in the playback menu allows you to immediately jump to 2, 4, 8, or 16 times magnification.
All of the other playback bells and whistles can be reached by pressing down on the four-way controller. There you'll find tools for:
- Image rotation
- Digital filters (Toy camera, retro, high contrast, extract color, water color, pastel, miniature, base parameter adjustment [brightness, saturation, etc], monochrome [with filters], color filters, soft, star burst, fisheye, slim, HDR, custom)
- Image resizing
- Image cropping
- Image comparison
- RAW processing
- Index print
- Image protect
- DPOF print marking
|RAW editing||Side-by-side image comparison|
Two of those features are worth some further discussion. The RAW processing option lets you take a RAW image, adjust its properties, and save the result as a JPEG. You can adjust the image type, quality, and color space, the Custom Image setting, white balance, sensitivity, high ISO noise reduction, plus shadow, highlight, chromatic aberration, and distortion correction. Very handy! The side-by-side feature lets you look at two photos simultaneously, with the ability to maintain the zoom and position for both.
There's only one movie-related editing tool on the K-x, and that's to grab a still frame from your video. Why some camera manufacturers can't add a simple "trim movie" feature is beyond me.
The K-x can display plenty of information about your photos, including your choice of histograms. The camera moves from one photo to the next without delay.
How Does it Compare?
When it was first announced, I wasn't terribly moved by the Pentax K-x. It seemed like just another entry-level digital SLR. After a survey of DCRP readers showed strong demand for a review of the K-x, I got my hands on one, and was quickly impressed with what Pentax has put together. The K-x is well built, feature-packed, responsive, and a great value for the money at just $649 (the street price is even lower). And it takes very good photos, too. It has its share of flaws, but the list is fairly short. The most annoying things about it are the lack of AF point illumination in the viewfinder, a mediocre LCD, and a tendency to clip highlights. Despite those issues, the Pentax K-x is a fine camera, and a great choice for those looking to step into the world of digital SLRs.
The K-x is a fairly compact digital SLR with a plastic outer shell and stainless steel frame. It feels quite solid in your hands, lacking the "plasticky" feel of many of its competitors. I found the camera easy to hold, thanks to a good-sized right hand grip. Pentax did a good job with the control layout on the camera, keeping buttons to a minimum and making them large and generally single-function. The K-x is available in four colors, ranging from quite black and navy blue colors to attention-grabbing stormtrooper white and Ferrari red. The camera uses the good old Pentax K-mount, and it supports all current Pentax lenses, plus all of the classics (even screwmount), though some of those will require an adapter. As with all of Pentax's D-SLRs, the K-x has a sensor-shift image stabilization system, so nearly every lens you attach will have shake reduction built right in. This same system can be used to shake dust off the sensor when the camera is turned on. On of the back of the camera is a disappointing 2.7" LCD display. While the specs list 230,000 pixels (typical for an entry-level D-SLR), in reality it seemed far less sharp than that, and the viewing angle was nothing to write home about, either. The viewfinder was also a let down, though not because of its size or coverage numbers. Pentax left out AF point illumination, so you never know what focus point the camera selected, unless you've done it manually. The K-x supports wireless flash control right out of the box, which is an unexpected extra on a camera in this class. And finally, the K-x uses AA batteries, which is something I always appreciate.
The K-x has a ton of features for an entry-level digital SLR. If you want to "set it and forget it", just set the mode dial to Auto Picture mode. The camera will select the proper scene mode for you, whether it's a portrait or macro shot. If you want to pick a scene mode yourself, there are plenty to choose from. Naturally, the K-x supports live view, which allows you to compose photos on the LCD display, just like you can on a point-and-shoot camera. You can detect faces, preview exposure and white balance, zoom in for precise manual focusing, and see a live histogram. As is usually the case, the live view feature has plenty of issues that come along with it. Those include very slow contrast detect autofocus (use phase difference for much better performance), difficulty focusing in low light, and poor low light visibility. The K-x also has a large selection of special effect filters, including a unique Cross Processing option. Enthusiasts will no doubt be pleased with the selection of manual controls on the K-x. You've got the usual manual exposure modes, plus Pentax's unique sensitivity priority mode, numerous ways to set the white balance (save for color temperature), and support for two RAW formats. There are also features to correct for barrel distortion, preserve highlights and shadows, and remove purple fringing. The K-x is also capable of recording movies at 1280 x 720 (at 24 frames/second) with monaural sound, for up to 11 minutes at the HQ setting. You can use the image stabilizer while you're recording, but the microphone will likely pick up the sound of the sensor moving around. The camera does not support continuous autofocus while recording movies, though I would be surprised if it did.
Camera performance was very good. The K-x is ready to go as soon as you flip the power switch. If you're shooting with the viewfinder, you won't wait long for the camera to lock focus, courtesy of the K-x's 11-point AF system. Things change dramatically if you're using live view, most notably with the two modes that use contrast detect AF. Instead of a half a second delay with phase difference AF, the contrast detect modes can take two or more seconds to lock focus. Shutter lag isn't a problem, though there is a slight delay when using live view and phase difference AF. Shot-to-shot delays are minimal, regardless of the image quality setting or whether you're using the flash. The K-x can shoot very quickly for a camera in the entry-level class, at frame rates of 4.6 frames/second. The only downside is that the buffer fills up relatively quickly, especially if you're shooting RAW. When equipped with decent NiMH rechargeables, the K-x's battery life is best in class. Pentax does not offer a battery grip for the K-x but then again, neither do most of its competitors.
Photo quality was also impressive. The K-x's weakest spot is in terms of exposure. Quite often the default exposure would be "off" a bit, so bracketing is a very smart idea. The K-x clips highlights more than I would like. Colors looked good, and the K-x has the sharpness set a little higher than on higher-end D-SLRs, which most consumers will appreciate (though the kit lens isn't terribly sharp toward the edges of the frame). Pentax has done a good job keeping noise levels at a minimum, with very clean-looking photos through ISO 3200 in good light, and ISO 1600 in low light. While there's a benefit to shooting RAW at middle sensitivities (e.g. ISO 1600, 3200), it doesn't help a whole lot when you approach the higher end of the spectrum. Purple fringing levels were moderate at times, though I blame the kit lens for that more than anything. To my surprise, redeye was a bit of an issue on the K-x, and there's no digital removal tool to help get rid of this annoyance.
I have just a few other things to mention regarding the K-x. There's no HDMI port, if you check the competition, most of them don't have one either. On a related note, Pentax does not include a video output cable with the camera, so if you plan on hooking the camera to your television, start looking for that cable. Finally, while it doesn't really effect overall camera behavior, the K-x's menu system feels very dated in the year 2010.
Despite a few flaws, most of which are minor, the Pentax K-x is an impressive entry-level digital SLR. It brings very good image quality (especially with a decent lens), snappy performance, tons of features, HD movie recording, and good build quality to the table for under $650 (with a lens). If you're looking for your first digital SLR, then the K-x should be high on your list.
What I liked:
- A lot of camera for the money
- Very good photo quality, with good high ISO performance
- Well designed, easy to hold compact body; available in four colors
- Sensor-shift image stabilization
- Full manual controls, with unique sensitivity priority mode
- Two RAW formats supported, plus way more custom functions than typical entry-level D-SLRs
- Generally well-implemented live view feature
- Fast startup, autofocus (with viewfinder), shot-to-shot speeds
- Very snappy continuous shooting, though could use more buffer memory
- Distortion, shadow and highlight levels, and purple fringing can be corrected as a photo is taken
- Numerous digital filters in both record and playback mode
- Built-in wireless flash support
- Records HD movies at 1280 x 720 (24 fps)
- Very good battery life; uses AA batteries
What I didn't care for:
- Tends to clip highlights; exposure is frequently off slightly
- Some redeye
- AF points not shown in optical viewfinder
- Kit lens is a bit soft toward edges of frame, and has moderate amounts of purple fringing at times
- LCD isn't terribly sharp; viewing angle isn't great, either
- Usual live view issues: slow contrast detect AF, poor low light focusing, image on LCD hard to see in low light
- Image stabilizer noise easily picked up by microphone in movie mode
- Dated menu system
- No video output cable included
- HDMI port would be nice
Some other entry-level digital SLRs worth looking at include the Canon EOS Rebel XS, Nikon D3000, Olympus E-620, and Sony Alpha DSLR-A380. The mirrorless, live view only Panasonic Lumix DMC-G1 and Samsung NX10 should not be overlooked, either.
As usual, I recommend heading to your local camera or electronics store to try out the Pentax K-x and its competitors before you buy!
Check out our gallery to see how the K-x's photos look!