Pentax K-3 Exposure
Pentax K-3 Image Quality
Saturation & Hue Accuracy
Very high mean saturation, with slightly below average hue accuracy.
|In the diagram above, the squares show the original color, and the circles show the color that the camera captured. More saturated colors are located toward the periphery of the graph. Hue changes as you travel around the center. Thus, hue-accurate, highly saturated colors appear as lines radiating from the center. Mouse over the links to compare ISOs, and click the links for larger versions.|
Saturation. The Pentax K-3's default image tone setting of "Bright" pushes most colors by quite a bit at base ISO, especially blues, greens, and purples. Mean saturation at ISO 100 is 121.4% or 21.4% oversaturated. That's about 11% higher than most other brands at default settings. Overall, colors are very bright and punchy, a trait we've come to expect from Pentax, and mean saturation remains higher than average throughout the ISO range. You can of course always select a different image tone preset and/or turn down settings such as saturation and contrast to suit your own tastes. Most consumer digital cameras produce color that's more highly saturated (more intense) than found in the original subjects. This is simply because most people like their color a bit brighter than life.
Skin tones. Caucasian skin tones from the Pentax K-3 were a touch yellow using Auto white balance in our test shots, however Manual white balance produced a more pinkish, "healthier" appearance. Good results here. Where oversaturation is most problematic is on Caucasian skin tones, as it's very easy for these "memory colors" to be seen as too bright, too pink, too yellow, etc.
Hue. The Pentax K-3's mean "delta-C" color error of 6.01 after correction for saturation at ISO 100 is a little below average for a DSLR these days. Most noticeable were moderate shifts in orange toward yellow and cyan toward blue, with minor shifts and some reds, yellows, and greens. (The cyan to blue shift is very common among the digital cameras we test; we think it's a deliberate choice by camera engineers to produce better-looking sky colors.) White balance shifts towards green at higher ISOs, which helps to increase mean color error to a maximum of 7.13 at ISO 51,200. Hue is "what color" the color is.
The Pentax K-3 lets you adjust Saturation and Contrast in nine steps each (Hue, High/Low Key and Sharpness are also adjustable in nine steps.) As can be seen below, the saturation adjustment works well, providing a reasonably fine-grained adjustment over a useful range of control. The saturation adjustment also has only a slight impact on contrast, which is good.
|Saturation Adjustment Examples|
The series of shots above shows results with several different saturation adjustment settings including both extremes. See the Thumbnails index page for more (look for the files named K3OUTBSATx.JPG). Click on any thumbnail above to see the full-sized image.
| See full set of test images
See thumbnails of all test and gallery images
Exposure and White Balance
Indoors, incandescent lighting
Very warm results with Auto white balance, too green with 2,600 Kelvin , but good color with Incandescent and Manual white balance settings. Average exposure compensation required.
|Auto White Balance Subtle
|Auto White Balance Strong
|Incandescent White Balance
|Manual White Balance
|2,600 Kelvin White Balance
The Pentax K-3's Auto white balance had a difficult time with the very warm color of the household incandescent bulbs used in this shot, producing a very warm image with a strong orange tint. Increasing the color correction in AWB mode to "Strong" (the default is "Subtle Correction") improved results, but color balance is still too warm and reddish. Results with the Incandescent setting are actually pretty good, though, just slightly on the warm side. The Manual setting produced the most accurate color balance, though just a touch cool. Unusually, the 2,600 Kelvin setting which matches the temperature of our lights produced a strong yellow/green cast. Note that a Color Temperature Enhancement (CTE) white balance option is also available (not shown), which exaggerates the temperature of ambient light. The Pentax K-3 required an average amount of exposure compensation of +0.3 EV for this shot. Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.
Very bright, slightly cool colors with about average exposure accuracy.
|Manual White Balance,
|Auto White Balance,
The Pentax K-3 handled tough outdoor lighting under harsh sunlight fairly well, producing very bright though slightly cool colors. Default contrast is on the high side (as most users prefer), resulting in some clipped highlights in the mannequins's shirt and some of the flowers, as well as some lost shadows in the flowers and the background, though all but the deepest shadows were quite clean if a bit posterized. +0.7 EV exposure compensation was required to keep the mannequin's face bright, which is about average for this scene. Skintones were just a touch warm and yellow using Auto white balance, so we preferred Manual white balance for our "Sunlit" Portrait shot here. Our Far-field shot was well exposed at 0 EV, and again with punchy, slightly cool color. Only a few highlights were clipped and very few shadows were lost, with very good detail in the shadows as well. Good results overall here.
Very high resolution, ~2,700 lines of strong detail from JPEGs, about the same from converted RAW files.
|Strong detail to
~2,700 lines horizontal
|Strong detail to
~2,700 lines vertical
|Strong detail to
~2,700 lines horizontal
ACR processed RAW
|Strong detail to
~2,700 lines vertical
ACR processed RAW
Our laboratory resolution chart reveals sharp, distinct line patterns down to about 2,700 lines per picture height in the horizontal direction, and to about the same 2,700 lph in the vertical direction in best quality JPEGs. Complete extinction of the pattern didn't occur until just past 3,000 lines in both directions. We weren't able to resolve more with an Adobe Camera Raw conversion, though complete extinction of the pattern was extended to about 3,800 lines. The ACR processed RAW images do however show a lot more color moiré, as they often do. Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail.
Sharpness & Detail
Very sharp images with excellent detail, though with moderate edge-enhancement on high-contrast subjects. Minor noise suppression visible at base ISO.
|Very good definition of
though with evidence of
|Subtle detail: Hair
Noise suppression tends to blur
detail in areas of subtle contrast,
though detail remains strong in
the darker parts of the model's hair here.
Sharpness. The Pentax K-3 produces very sharp images with excellent detail at default settings. Images are slightly oversharpened as edge enhancement artifacts are visible on high-contrast subjects such as the sharpening halos around the lettering and border in our Mas Portell bottle label above left, but overall results are still quite good. Edge enhancement creates the illusion of sharpness by enhancing color and tonal differences right at the edge of a rapid transition in color or tone.
Detail. The crop above right shows only minor detail loss due to noise suppression. Individual strands are still distinguishable even in the lighter shadows, though they begin to merge as shadows deepen, and in places where the tone and color of adjacent strands is very close. Still, very good performance here, though chroma noise is a little high in the hair. Some individual strands of hair also show aliasing in the form of "jaggies", however the K-3's selectable AA filter should help prevent those from occurring when enabled (AA Filter Simulation was off by default). Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.
Anti-aliasing Filter Simulator
During the exposure, the Pentax K-3's anti-shake actuator can oscillate the sensor assembly microscopically in either a linear (Type 1) or circular (Type 2) motion, simulating the effects of an anti-aliasing (or optical low-pass) filter. To see the effect on image sharpness and alias artifacts, roll over the links in the table below to compare the USAF Resolution target and green/black starburst taken from our Multi target at base ISO:
As you can see, AA Filter Simulation Type 1 blurs fine detail slightly, while Type 2 offers a slightly stronger effect (and slightly shifted the image vertically because of the circular motion), which should go a long way to reduce aliasing artifacts and moiré as can be seen in the starburst crop. It really is quite amazing to have on-demand anti-aliasing filtering like this. Note that the AA Filter Simulator is not available in movie mode or during HDR capture, and the full effect cannot be achieved at shutter speeds faster than 1/1000s.
RAW vs In-Camera JPEGs
As noted above, the Pentax K-3 does a great job at capturing lots of fine detail in its JPEGs, but more detail can often be obtained from carefully processing RAW files, while at the same time reducing sharpening artifacts. Take a look below, to see what we mean:
In the table above, we compare an in-camera JPEG taken at base ISO using default noise reduction and sharpening (on the left) to the matching RAW file converted with Adobe Camera Raw 8.3 using default noise reduction with some strong but tight unsharp masking applied in Photoshop (300%, radius of 0.3 pixels, and a threshold of 0).
As is usually the case, Adobe Camera Raw delivers finer detail than the camera's processing, and its light default noise reduction does much better with our difficult red-leaf swatch, even resolving some of its thread pattern which the camera blurred away as noise. ACR also did a better job with color, rendering the pink fabric closer to reality instead of the more magenta interpretation of the camera. Adobe Camera Raw also extracted more detail in the mosaic, but left behind some of the chroma noise and false color artifacts which the camera removed. Overall, though, the Pentax K-3 does a very good job with its JPEGs, but as is usually the case you can extract even more detail (with more accurate color and fewer sharpening artifacts) with a good RAW converter.
ISO & Noise Performance
Very good handling of noise versus detail in JPEGs to ISO 3200.
|Noise Reduction = Auto (Default)|
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1600||ISO 3200|
|ISO 6400||ISO 12,800||ISO 25,600|
The Pentax K-3's images are very clean and detailed from ISO 100 through 800, with just a touch of luminance noise becoming more visible in the shadows and darker midtones as ISO increases. Detail is still very good at ISO 1600, with a tight film-like noise "grain" and very little fine detail lost to noise reduction (except in reds). At ISO 3200, there's increased blurring and more visible noise "grain" particularly in the shadows, but fine detail is still quite good, though chroma noise is a little more noticeable in darker hair and shadows. ISO 6400 shows stronger luminance and chrominance noise as well as a slight speckled effect in flat areas, though there's still a fair amount usable detail left. Image quality at ISO 12,800 and above falls off quickly, though, with much stronger luminance noise and speckling, and much less detail than at lower sensitivity levels. Chroma noise in the form of yellow and purple blotches becomes a noticeable issue at ISOs 25,600 and 51,200, and overall color balance shifts toward green, particularly at the highest ISO.
Overall, though, high ISO noise performance is excellent for a 24-megapixel APS-C camera and competitive with its closest rival, the Nikon D7100, except in low-contrast reds. Note that these images were shot using the Pentax K-3 "Auto" noise reduction setting. The Pentax K-3 offers an unusually flexible amount of control over noise reduction applied to its JPEGs. In addition to "Auto", you can adjust how much NR is applied ("Off", "Low", "Medium" or "High") at all ISOs, or you can select "Custom" which allows you to choose from the same four options at each ISO sensitivity setting (in whole EV increments). Of course, the impact of noise and detail loss are highly dependent on the size the photos are printed at, and pixel-peeping on-screen has surprisingly little relationship to how the images look when printed: See the Print Quality section below for recommended maximum print sizes at each ISO.
A note about focus for this shot: We shoot this image at f/4, using one of three very sharp reference lenses (70mm Sigma f/2.8 macro for most cameras, 60mm f/2.8 Nikkor macro for Nikon bodies without a drive motor, and Olympus Zuiko 50mm f/2.0 for Four Thirds and Micro Four Thirds bodies). To insure that the hair detail we use for making critical judgements about camera noise processing and detail rendering is in sharp focus at the relatively wide aperture we're shooting at, the focus target at the center of the scene is on a movable stand. This lets us compensate for front- or back-focus by different camera bodies, even those that lack micro-focus adjustments. This does mean, though, that the focus target itself may appear soft or slightly out of focus for bodies that front- or back-focused with the reference lens. If you click to view the full-size image for one of these shots and notice that the focus target is fuzzy, you don't need to email and tell us about it; we already know it. :-) The focus target position will simply have been adjusted to insure that the rest of the scene is focused properly.
Extremes: Sunlit, dynamic range, and low light tests
Very high resolution with good highlight and excellent shadow detail. Very good low-light performance, capable of capturing bright images in near darkness.
|0 EV||+0.3 EV||+0.7 EV|
The Pentax K-3 handled the deliberately harsh lighting well in the above test. Though default contrast is quite high, highlight and especially shadow detail are very good. (The K-3's contrast adjustment also did a good job of decreasing overall contrast though it did impact saturation; see the section below.) The +0.7 EV exposure did the best job here, as we thought +0.3 and 0 EV were too dim in the face. Some highlights were blown in the mannequin's shirt and bright flowers at +0.7 EV, though, however very good detail was preserved in the shadows with relatively low levels of noise. Note that these shots were captured with the Pentax K-3's D-Range control set to "Off."
Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here. In actual shooting conditions, be sure to use fill flash in situations like the one shown here; it's better to shoot in open shade whenever possible.)
Just as with its saturation adjustment, the Pentax K-3's contrast adjustment offers a fairly wide range of settings (-4 to +4), and the contrast steps are actually a little finer than those for saturation, which is even more to our liking.
|Contrast set to lowest,
|Contrast set to lowest,
At its lowest contrast setting, the K-3 did a good job of bringing nice detail out of the shadows as well as preserving additional highlight detail in the mannequin's shirt and flowers, but skintones in the "Sunlit" Portrait were a bit too flat for our tastes, and colors in general were less saturated.
|Contrast Adjustment Examples|
The series of shots above shows results with several different contrast adjustment settings, showing a range between both extremes including the default. The camera's contrast adjustment had some effect on color saturation, reducing and increasing it along with contrast. Contrast and saturation are actually fairly closely coupled, so this is unfortunately not that unusual. Click on any thumbnail to go to the full-size image.
The Pentax K-3 offers four Shadow Correction levels (Auto, Low, Medium and High, plus Off) as well as two Highlight Correction levels (Auto and On, plus Off). As the name implies, Shadow Correction works to raise shadow levels while attempting to keep highlights and midtones as they are, and inversely, Highlight Correction attempts to reduce highlights without darkening shadows and midtones. Both can be used simultaneously. See the images below to see their effect on our high-contrast "Sunlit" Portrait test shot.
Outdoor Portrait D-Range Examples
Mouse over the links to see how the various settings for D-Range affects our "Sunlit" Portrait shot, and click on a link to get to the full-res image. (The effect can be a little subtle in shots like those above, so we decided to use a mouse-over to better show how each setting compares to Off.)
Shadow Correction. Above, we see a gradual lightening of shadows and midtones as the Shadow Correction setting is increased, with only a small impact to highlights. If you look closely at the shadow detail, you will notice an increase in noise as the setting is turned higher, but that's to be expected and noise levels are still pretty low. The camera reports an ISO of 100 for all four settings of Shadow Correction.
Highlight Correction. Highlight Correction works as expected when highlights are blown, toning them down to protect them while keeping shadows and midtones roughly the same. It also raised ISO to 200.
Far-field D-Range Examples
Here are the results of the available D-Range settings with our Far-field shot. Again, we see a lightening of shadows as the Shadow Correction setting is increased, and a slight reduction in highlights with Highlight Correction.
The Pentax K-3 has a High Dynamic Range (HDR) capture mode where the camera takes three images (underexposed, normal, and overexposed) in quick succession and combines them in-camera into one image. If performed properly, this method should result in much higher dynamic range, without the additional noise penalty that comes with boosting sensitivity or lightening shadows. (In fact, it can reduce shadow noise by combining shadows from the overexposed shot.)
There are four HDR settings available: Auto, and HDR 1/2/3 providing three blend settings, and each setting has three possible exposure ranges (±1 EV, ±2 EV and ±3 EV). There's also an optional Auto Align feature for use when shooting without a tripod, which is enabled by default on the K-3.
Far-field HDR Examples
Mouse-over the links above to compare thumbnails, and click on them to access full-resolution versions.
The Auto settings worked reasonably well on our Far-field test shot, reducing highlights and bringing out shadow detail. HDR1 mode produced a relatively realistic image though with an obvious HDR look, but HDR2 seems to have failed producing a very bright, overexposed image. HDR3 resulted in an unnatural, very HDR-ish image with strong halos. As with most HDR systems there is a slight focal-length crop with Auto Align active, and watch out for ghosting that can occur when subjects move between exposures.
Interestingly, HDR is still supported when shooting the K-3 in RAW mode (in many cameras, the two modes are mutually exclusive), however the resulting RAW file is three times as large as a standard shot. It appears the K-3 is just bundling the individual captures into one file, to be processed later by their Digital Camera Utility software which can apparently blend or extract the separate RAW files. (We haven't tried the bundled software yet, but Photoshop CS6 and Lightroom 5 both seem to ignore the additional images in HDR PEF and DNG files.)
Dynamic Range Analysis (RAW mode)
While we once performed our own dynamic range measurements based on in-camera JPEGs as well as converted RAW images (when the camera was supported by Adobe Camera Raw), we've switched to using DxO Labs' results from their DxOMark website. As technology advanced, the dynamic range of modern high-end cameras in some cases exceeded the range of the Stouffer T4110 density scale that we used for our own measurements. DxO's approach based on RAW data before demosaicing is also more revealing, because it measures the fundamental dynamic range of the sensor, irrespective of whatever processing is applied to JPEGs, or to RAW data by off-the-shelf conversion software.
In the following, we use DxO's "Print" dynamic range results, which are scaled based on camera resolution. As the name suggests, this scaling corresponds to the situation in which you print at a given size, regardless of how many megapixels the camera might have. (In other words, if you've decided to make a 13x19 inch print, that's the size you're printing, whether the camera's resolution is 16 or 300 megapixels.) For the technically-minded, you can find a discussion of the reasoning behind this here on the DxOMark website. Also note that DxO Labs uses a signal-to-noise (SNR) threshold of 1 when defining the lower boundary of acceptable luminance noise in their dynamic range measurements, which corresponds to the "Low Quality" threshold of the Imatest software we used to use for this measurement.
As you can see from the above graph (click for a larger image) comparing the Pentax K-3's normalized dynamic range to two competitors, the K-3's dynamic range isn't quite as good as its closest rival, the Nikon D7100, particularly at low to moderate ISOs, but it's still very good, ranging from a maximum of 13.4 EV at base ISO down to 5.2 EV at maximum ISO. The Pentax K-3's dynamic range is however significantly better than the Canon 70D's at lower ISOs, offering an almost 2 EV advantage at base ISO. At higher ISOs, the three cameras perform similarly, to the point where differences in dynamic range may be difficult to distinguish in real-world images. Click here to visit the DxOMark page for the Pentax K-3 for more of their test results and additional comparisons.
Low Light. The Pentax K-3 performed very well here, able to capture usable images down to the 1/16 foot-candle light level (about 1/16 as bright as average city street lighting at night), at all ISO settings. Noise is quite low up to ISO 1600, and even at higher ISOs there's still a lot of detail to work with especially when high ISO NR is set to "Off." (Except for the "No NR" shots in the table above, these were all shot using the default Auto NR settings.)
Color balance with Auto white balance is pretty good which isn't always the case, with just a slightly cool bias that becomes cooler as light levels drop. At very high ISOs, though, overall color balance shifts towards green.
We did not detect any significant issues with hot pixels or heat blooming, however some minor horizontal banding (pattern noise) can be seen at the highest ISOs.
The Pentax K-3's phase-detection autofocus system was able to focus on our test subject down to just above the 1/8 foot-candle light level using an f/2.8 lens with its AF assist light turned off. That's not as good as most prosumer DSLRs, though it was able to focus in total darkness with the focus assist lamp enabled.
(Keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any blurring from camera movement. A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)
How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.
NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) Digital SLRs like the Pentax K-3 do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
Excellent 30 x 40 inch prints at ISOs 100 and 200; a nice 11 x 14 at ISO 1600; a good 4 x 6 at ISO 12,800.
ISO 100/200 prints are terrific at 30 x 40 inches, with rich colors and super sharp detail. Wall display prints are possible at 36 x 48 inches. Note that most Pentax cameras oversaturate our pink fabric swatch and also render it as more magenta than it actually is, and the K-3 is no exception to this one common oddity from the Pentax line.
ISO 400 produces a nice 24 x 36 inch print, which is a size larger than most APS-C-sensored cameras are capable of printing. It performs especially well here in our difficult red fabric swatch, where many a good camera already begins to show signs of ISO strain.
ISO 800 is where the K-3 starts to look more like the K-5 II and IIs. 20 x 30s start to show typical noise in flatter areas of our target, and lose some detail and contrast in our red fabric swatch, both of which are quite common. We can give the 16 x 20s at this ISO our "good" stamp of approval.
ISO 1600 produces similar results to its predecessors, allowing for good 11 x 14s but losing all detail in our red fabric swatch. Otherwise, though, the prints are nice and crisp.
ISO 3200 yields good 8 x 10 inch prints, with only a mild trace of noise in shadowy areas of our target.
ISO 6400 prints look good at 5 x 7, and identical to the K-5 II and IIs. We'd hoped for a good 8 x 10 here, which is a high mark for ISO 6400, but the K-3 didn't quite make the grade due to noise levels.
ISO 12,800 prints a good 4 x 6, with mild noise in shadows but still retaining good overall color.
ISOs 25,600 and 51,200 do not yield good prints and are best avoided.
Stepping up to a 24MP sensor, the Pentax K-3 sets a much higher resolution benchmark than the K-5 II and IIs at 16MP, and the results show in the print quality department at ISOs 100-400, allowing a full print size higher at each setting. The results from ISO 800 and up however tell a different story, as there is virtually no discernible difference in print quality between the K-3 and its lower-resolution siblings. So if you are considering the K-3 and will be making sizable prints from the fruits of your labors, it will be at the lower ISOs that you will see the biggest difference in JPEG image quality as compared to the K-5 II and IIs.
Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 Mark II studio printer, and on the Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Pentax K-3 Photo Gallery .
Not sure which camera to buy? Let your eyes be the ultimate judge! Visit our Comparometer(tm) to compare images from the Pentax K-3 with those from other cameras you may be considering. The proof is in the pictures, so let your own eyes decide which you like best!