Pentax K-5 II 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.|
Skin tones. Caucasian skin tones from the Pentax K-5 II were a touch yellow using auto white balance in our test shots, while manual white balance produced a more pinkish, "healthier" appearance. Because of the push in reds, though, skintones were a little too ruddy. 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-5 II's mean "delta-C" color error of 6.1 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.) Hue is "what color" the color is.
The Pentax K-5 II lets you adjust the image 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 worked well, providing a reasonably fine-grained adjustment over a useful range of control. The saturation adjustment also had almost no impact on contrast. That's how a saturation control should work, but we've often found interactions between saturation and contrast adjustments on cameras we've tested.
|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 K52OUTBSATx.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 default Auto and 2,600 Kelvin white balance settings, too cool with Incandescent, but good color with Manual white balance setting. Slightly higher than 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-5 II'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" (default is "Subtle Correction") improved results, but color balance was still a bit warm and reddish. Results with the Incandescent setting on the other hand were too cool with a blue bias. The Manual setting produced the most accurate color balance, though 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 the ambient light. The Pentax K-5 II required a slightly higher than average amount of exposure compensation of +0.7 EV for this shot. (The average for this scene is +0.3 EV for the cameras we've tested.) 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.
Bright, slightly cool colors with about average exposure accuracy.
|Manual White Balance,
|Auto White Balance,
The Pentax K-5 II handled tough outdoor lighting under harsh sunlight fairly well, producing 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. +0.7 EV exposure compensation was required to keep the model's face reasonably bright, which is about average for this scene. Skintones were just a touch yellow using auto white balance, so we preferred manual white balance for our "Sunlit" Portrait shot here, though skintones were a bit ruddy. Our Far-field shot was slightly underexposed at 0 EV, but again with punchy, slightly cool color. Almost no 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, ~2,100 to 2,200 lines of strong detail from JPEGs, a little higher from converted RAW files.
|Strong detail to
~2,200 lines horizontal
|Strong detail to
~2,100 lines vertical
|Strong detail to
~2,300 lines horizontal
ACR processed RAW
|Strong detail to
~2,200 lines vertical
ACR processed RAW
Our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,200 lines per picture height in the horizontal direction, and about 2,100 in the vertical direction in best quality JPEGs. Complete extinction didn't occur until about 2,700 lines in both directions. We were able to resolve a little more with an Adobe Camera Raw conversion, about 2,300 lines in the horizontal direction and about 2,200 in the vertical, and complete extinction of the pattern was extended to about 3,000 lines. The ACR processed RAW images did show more color moire, 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, detailed images overall, 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-5 II produced very sharp images with very good detail at default settings. Images were slightly oversharpened as edge enhancement artifacts are visible on high-contrast subjects such as the sharpening halos around thicker branches and the pine codes in the crop above left, but overall results were still quite good (albeit with a bit too much contrast and saturation for our tastes). 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. 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.
Raw vs In-Camera JPEGs
As noted above, the Pentax K-5 II does a pretty good job at capturing lots of detail, 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, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking the link will load the full resolution image. Examples are shot at ISO 100, and consist of an in-camera Best quality JPEG (left link) and the matching RAW file processed through Adobe Camera Raw (ACR) version 7.4, then sharpened in Photoshop. For the Pentax K-5 II's RAW files, we found good results with strong but tight 300% unsharp masking with a 0.3 pixel radius.
As is frequently the case, the demosaicing and sharpening from Adobe Camera Raw and Photoshop deliver finer detail than the camera's processing. Looking very closely at the images, ACR extracted a bit more fine detail that wasn't present in the JPEGs, but results also look more natural with reduced saturation and contrast. There's also a touch more noise visible from the converted RAW file (though noise levels are still very low). You can always adjust noise reduction to your liking, though, which is one of the advantages of shooting RAW and processing the images yourself.
ISO & Noise Performance
Excellent high ISO performance, with very good handling of noise versus detail to ISO 3,200.
|Noise Reduction = Auto (Default)|
|ISO 80||ISO 100||ISO 200|
|ISO 400||ISO 800||ISO 1,600|
|ISO 3,200||ISO 6,400||ISO 12,800|
|ISO 25,600||ISO 51,200|
The Pentax K-5 II's images are very clean and detailed from ISO 80 through 800, which 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 1,600, with a tight film-like noise "grain" and very little fine detail lost to noise reduction. At ISO 3,200, there's increased blurring and more visible noise "grain" particularly in the shadows, but fine detail is still quite good, though subtle detail in reds take a larger hit. ISO 6,400 shows stronger luminance and chrominance noise as well as increased blurring, though there's still a fair amount usable detail left. Images quality at ISO 12,800 and above falls off quickly, with much stronger luminance noise and much less detail than those 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.
Overall, though, high ISO noise performance is excellent for a 16-megapixel APS-C camera and at least as good as the K-5's, if not slightly better. Note that these images were shot using the Pentax K-5 II "Auto" noise reduction setting. The Pentax K-5 II 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-5 II 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-5 II'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 model's shirt and bright flowers at +0.7 EV, though, while very good detail was preserved in the shadows with low levels of noise. Note that these shots were captured with the Pentax K-5 II'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.)
Dynamic Range Analysis
A key parameter in a digital camera is its Dynamic Range, the range of brightness that can be faithfully recorded. At the upper end of the tonal scale, dynamic range is dictated by the point at which the RGB data "saturates" at values of 255, 255, 255. At the lower end of the tonal scale, dynamic range is determined by the point at which there ceases to be any useful difference between adjacent tonal steps. Note the use of the qualifier "useful" in there: While it's tempting to evaluate dynamic range as the maximum number of tonal steps that can be discerned at all, that measure of dynamic range has very little relevance to real-world photography. What we care about as photographers is how much detail we can pull out of the shadows before image noise becomes too objectionable. This, of course, is a very subjective matter, and will vary with the application and even the subject matter in question. (Noise will be much more visible in subjects with large areas of flat tints and subtle shading than it would in subjects with strong, highly contrasting surface texture.)
What makes most sense then, is to specify useful dynamic range in terms of the point at which image noise reaches some agreed-upon threshold. To this end, Imatest computes a number of different dynamic range measurements, based on a variety of image noise thresholds. The noise thresholds are specified in terms of f-stops of equivalent luminance variation in the final image file, and dynamic range is computed for noise thresholds of 1.0 (low image quality), 0.5 (medium image quality), 0.25 (medium-high image quality) and 0.1 (high image quality). For most photographers and most applications, the noise thresholds of 0.5 and 0.25 f-stops are probably the most relevant to the production of acceptable-quality finished images, but many noise-sensitive shooters will insist on the 0.1 f-stop limit for their most critical work.
JPEG. The graph at right (click for a larger version) was generated using Imatest's dynamic range analysis for an in-camera Pentax K-5 II JPEG file with a nominally-exposed density step target (Stouffer 4110). At the base ISO of 100 (the optimal ISO for dynamic range), with D-Range Expansion set to Off and default Contrast, the graph shows 11.5 f-stops of total dynamic range, and 7.43 f-stops at the "High" Quality level. These are are good results for an APS-C model. Compared to the Pentax K-5, the K-5 II scored almost identically at the highest quality level with its JPEG producing 7.43 versus 7.22 f-stops. The K-5 II scored better in total dynamic range with 11.5 vs 10.5 f-stops, so it seems that Pentax has made some improvements to its JPEG engine since the K-5. Note though that this measurement has a margin of error of about 1/3 f-stop, so differences of less than 0.33 can be ignored.
Raw. The graph at right is from the same Stouffer 4110 stepchart image captured as a RAW (.DNG) file, processed with Adobe Camera Raw using the Auto setting and tweaked from there. As can be seen, the score at the highest quality level increased over two f-stops from 7.43 to 10.4 f-stops, while total dynamic range increased just over two f-stops from 11.5 to 13.1. These results are excellent, essentially matching the K-5's 10.2 score at the highest quality level, and exceeding it in total dynamic range. Results at the highest quality level were also significantly better than the K-30's, which scored 9.86 f-stops in our tests. It's worth noting here is that ACR's default noise reduction settings reduced overall noise somewhat (see the plot in the lower left-hand corner) relative to the levels in the in-camera JPEG, which would tend to boost the dynamic range numbers for the higher quality thresholds.
Just as with its saturation adjustment, the Pentax K-5 II'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-5 II did a really excellent job of bringing nice detail out of the shadows as well as preserving more highlight detail in the mannequin's shirt and flowers, but skin tones in the "Sunlit" Portrait were a bit too flat for our tastes, and colors in general in the Far-field shot 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 quite an 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-5 II offers three Shadow Correction levels (Low, Medium and High, plus Off) as well as one Highlight Correction level (On/Off). Unlike the K-30, there are no Auto settings. 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. 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, though highlights are also affected to some degree. 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 three settings of Shadow Correction.
Highlight Correction. Highlight Correction set to On did reduce the number of bright highlights, but also boosted shadows a bit. It also raised ISO to 160.
Far-field D-Range Examples
Here are the results with our Far-field shot. Again, we see a lightening of shadows as the Shadow Correction setting is increased. Highlight Correction worked as expected though again there weren't many highlights clipped in the first place, and it also boosted shadows somewhat.
The Pentax K-5 II 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 five HDR settings available: Auto, Standard, and HDR 1/2/3 providing +/-1 EV, +/-2 EV and +/-3 EV exposure ranges respectively.
Far-field HDR Examples
The Auto and Standard HDR settings worked reasonably well on our Far-field test shot, reducing highlights and bringing out shadow detail. HDR 1 produced a relatively realistic image, but higher settings were too much for this scene, resulting in very flat and unnatural looking images with strong halos. As with most HDR systems, watch out for ghosting that can occur when subjects move between exposures. The K-5 II also has an Auto Align function which should let you shot HDR images without the use of a tripod, but we didn't test that feature in the lab. As you'd expect, HDR mode is not supported when shooting RAW or RAW+JPEG files.
Low Light. The Pentax K-5 II 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 was quite low up to ISO 1,600, and even a higher ISOs there's still a lot of detail to work with especially when high ISO NR is set to "Off." As mentioned previously, the Pentax K-5 II gives you four options for high ISO noise reduction: Auto, Off, Low, Normal, and High, and you can choose the level of noise reduction for each ISO, so you have a lot of flexibility in deciding how much noise to trade for detail. 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 was pretty good which isn't always the case, with just a slightly cool bias that became cooler as light levels dropped. At very high ISOs, chroma noise shifted overall color balance, sometimes towards magenta or green, but that's not unusual.
We did not detect any significant issues with hot pixels, banding, or heat blooming.
The Pentax K-5 II's phase-detection autofocus system was able to focus on the subject down to below the 1/16 foot-candle light level using an f/2.8 lens with its AF assist light turned off, and in total darkness with the focus assist lamp enabled. In Live View mode, the K-5 II's contrast-detect autofocus was also able to focus down to below the 1/16 foot-candle level, which is excellent.
(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-5 II do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects..)
Excellent print quality up to 24 x 36 inches at ISO 80/100/200; ISO 1600 capable of a good 11 x 14 inch print; ISO 12,800 still able to deliver a good 4 x 6. (Note: the K-5 II creates noticeable oversaturation in some colors of our test images.)
ISO 400 prints lose only a minor amount of detail in a few areas like the mosaic tiles, but are quite sharp at 20 x 30 inches.
ISO 800 images still look decent at 20 x 30, but show marginal loss in contrast in our difficult target red leaf swatch and some apparent noise in the shadowy areas of our target. To be safe we'll call 16 x 20 good at this ISO.
ISO 1,600 prints at 11 x 14 lose all contrast detail in our target red swatch, but are otherwise quite good.
ISO 3,200 makes a nice 8 x 10 inch print, again losing all detail in our red swatch but good in all other areas.
ISO 6,400 prints a nice 5 x 7, with only minor grain in the shadows.
ISO 12,800 prints a nice 4 x 6, which still is a good size for this ISO.
ISO 25,600/51,200 prints are not usable at any size and are best avoided.
The Pentax K-5 II with its 16.3-megapixel APS-C CMOS sensor yields a nice range of printed images across most of the ISO spectrum, producing comparable print sizes to most of its competitors in this sensor size and price range. Note however that at all sizes and ISO ranges our target magenta fabric swatch has a noticeable boost in saturation, and is tinted slightly more towards purple than the actual swatch color. Other colors are oversaturated as well.
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.)