Pentax K-5 Image Quality

Saturation & Hue Accuracy
Bright, intense colors with moderate to strong oversaturation of dark blues, purples, reds, and greens.

Saturation. The Pentax K-5's default image tone setting of "Bright" pushes most colors by quite a bit, especially blues, greens, and some reds. Overall, images were very bright and punchy, with color that was a little over the top for a prosumer SLR, but trademark Pentax. You can of course always select a different image tone preset (see below) 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-5 were a touch yellow using auto white balance, while manual white balance produced a more pinkish, "healthier" appearance. 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 showed a few color shifts relative to the correct mathematical translation of colors in its subjects, but had acceptable accuracy overall when using default settings. Most noticeable was a shift in orange toward yellow, with some shifts in cyans, blues, and reds as well. (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.

Custom Image
The Pentax K-5 offers nine preset "Custom Image" options. You can adjust Saturation, Hue, High/Low Key, Contrast, Sharpness, Filter Effects and Toning parameters to your liking. (Some adjustments are not available depending on the Custom Image type.)

Mouse over the links above to see the effect of the presets on our Still Life target. Click on a link to load the full resolution image.

Saturation Adjustment
The Pentax K-5 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 has almost no impact on contrast. That's how a saturation control should work, but we've often found interactions between saturation adjustments and image contrast (and vice versa) on the cameras we test.

The series of shots above shows results with several different saturation adjustment settings, showing the minimum step size around the default, as well as both extremes. See the Thumbnails index page for more (look for the files named K-5OUTBSATx.JPG). Click on any thumbnail above to see the full-sized image.

Exposure and White Balance

Indoors, incandescent lighting
Very warm results with Auto white balance, though good color with Incandescent and Manual white balance settings. Slightly higher than average exposure compensation required.

The Pentax K-5's auto white balance had a difficult time with the very warm color balance of the household incandescent bulbs used in this shot, something we find disappointing in a camera in this price and performance range. Results with the Incandescent setting were pretty good, just bit on the warm side. The 2,600 Kelvin setting which should match our tungsten lamps produced a strong greenish cast. The Manual setting produced the most accurate results, though still a touch cool. The Pentax K-5 required a slightly higher than average amount of exposure compensation of +0.7 EV for this shot. (The average among cameras we've tested is +0.3 EV.) 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.

Like other more recent Pentax SLRs, the K-5 offers two settings for Auto White Balance correction in Tungsten light: Subtle and Strong. As you can see here with our Still Life target under tungsten lighting, the Strong setting does a better job correcting for the reddish cast than the default Subtle setting, but still leaves quite a warm tone. A Color Temperature Enhancement (CTE) white balance option is also available, which exaggerates the temperature of the ambient light producing a very strong orange cast here.

Outdoors, daylight
Bright colors with excellent exposure and good highlight/shadow detail preservation.

The Pentax K-5 handled tough outdoor lighting under harsh sunlight pretty well, producing bright images with accurate exposure. Default contrast was a bit on the high side (as most users prefer), resulting in some clipped highlights in the model's shirt and some of the flowers, as well as some lost shadows in the flowers and the background, though remaining shadow detail is unusually clean (as it was on the Nikon D7000). No exposure compensation was required to keep the model's face reasonably bright, which is much better than the average of +0.7 EV usually required for this scene. Skin tones were just a touch yellow using auto white balance, so we preferred manual white balance for outdoor portraits. The house shot was also well exposed at 0 EV, with only a few clipped highlights in the white trim, while shadow detail was quite good. Very good results overall here.

See full set of test images with explanations
See thumbnails of all test and gallery images

Resolution
Very high resolution, ~1,900 lines of strong detail from JPEGs, about 2,100 lines from converted RAW files.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,900 lines per picture height in both the horizontal and vertical direction in JPEGs. (Some might argue for over 2,000 lines, but aliasing artifacts begin to appear earlier.) Complete extinction didn't occur until around 2,800 lines in both directions. We were able to extract more resolution (to about 2,100 lines) with RAW files processed through Adobe Camera RAW, with complete extinction extended to around 3,200 lines. The ACR processed RAW images were also crisper (thanks to strong/tight unsharp masking in Photoshop), and didn't show as many jagged edges on fine diagonal lines as the camera JPEGs did, though color moire was a bit higher. 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.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Sharp images overall, though minor edge-enhancement on high-contrast subjects. Minimal noise suppression visible at base ISO.

Sharpness. The Pentax K-5 produced sharp images with very good detail at default settings. Some minor edge enhancement artifacts are visible on high-contrast subjects such as some of the branches in the crop above left, but overall results are 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 minimal detail loss due to noise suppression, as the darker areas of the model's hair show a lot of detail. 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. 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 does a pretty good job at capturing lots of detail, but more detail can be obtained from carefully processing RAW files, without introducing additional 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 include in-camera Premium JPEG as well as the matching RAW file processed through Adobe Camera Raw (ACR) version 6.3, then sharpened in Photoshop. For the Pentax K-5's RAW files, we found best results with strong but tight 450% unsharp masking with a 0.3 pixel radius.

As is frequently the case, the demosaicing and sharpening in Adobe Camera and Photoshop deliver finer detail than the camera. Looking very closely at the images, ACR extracts quite a bit more detail that wasn't present in the JPEGs, but renders colors and contrast differently than the default camera settings, and there's also a bit more noise visible. You can always adjust those to your liking, though, which is one of the advantages of shooting RAW and processing the images yourself.

ISO & Noise Performance
Very good handling of noise vs detail to ISO 1,600; one of the best APS-C performances to date.

The Pentax K-5's images were very clean at ISO 100 through 800, which just a touch of luminance noise becoming more visible in the shadows and darker midtones as ISO is increased. Detail was 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", but fine detail is better than average for an APS-C sensor of similar resolution. ISO 6,400 shows stronger luminance noise and increased blurring, though there's still quite a bit of usable detail left. Chroma noise is surprising well controlled up to ISO 6,400. Images at 12,800 and above are noticeably less detailed than those at lower sensitivity levels, and ISO 51,200, not surprisingly, shows strong noise reduction artifacts and a lot of chroma noise as well, in the form of yellow and dark purple blotches in midtones and shadows.

Note that these images were shot using the Pentax K-5 default "Auto" noise reduction setting. The Pentax K-5 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 and low light tests
Very high resolution with very good highlight and shadow detail. Very good low-light performance, capable of capturing bright images in near darkness, though autofocus and metering struggled at lower light levels.

Sunlight:
The Pentax K-5 handled the deliberately harsh lighting very well in the above test. Though default contrast is a little high, highlight and especially shadow detail are very good. The camera's contrast adjustment also did a good job of decreasing overall contrast though it did impact saturation; see the section below. The default exposure (0 EV) did the best job here, as we thought that too many highlights were lost at +0.3 and especially +0.7 EV. Even at 0 EV, some highlights were blown in the model's shirt and bright flowers, but not as many as we're used to seeing, while very good detail was preserved in the shadows with unusually low levels of noise. These shots were captured with the Pentax K-5's D-Range controls set to their defaults of "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.)

Contrast Adjustment
Just as with its saturation adjustment, the Pentax K-5'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.

At its lowest contrast setting, the K-5 did a really excellent job of bringing nice detail out of the shadows as well as preserving a bit more highlight detail in the model's shirt and flowers, but skin tones in the "Outdoor" Portrait were a bit too flat for our tastes, and colors in general in the Far-field House shot were noticeably less saturated.

The series of shots above shows results with several different contrast adjustment settings, showing the minimum step size around zero, as well as both extremes. The Pentax K-5 actually defaults contrast to +1. The camera's contrast adjustment had quite an effect on color saturation, reducing it along with contrast. Contrast and saturation are actually fairly closely coupled, so this is unfortunately not unusual. While you can see the extremes, it's hard to really evaluate contrast on small thumbnails like these, click on any thumbnail to go to the full-size image.

Face Detection
The Pentax K-5 has a face-detection AF/AE option in Live View mode.

As you can see above, using Face Detection AF mode in Live View impacts exposure as well. Here, the image with face detection enabled was actually a little dimmer than without.

D-Range Settings
The Pentax K-5 offers three Shadow Correction levels (Low, Medium, and High) as well as one Highlight Correction setting (On/Off). As the name implies, Shadow Correction works to raise shadow levels while attempting to keep highlights and midtones as they are, and likewise, 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.

Mouse over the links to see how the various settings for D-Range affects our "Outdoor" 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 as the Shadow Correction setting is increased, but there is also a slight increase in highlight clipping. 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 80 for all three settings of Shadow Correction.

Highlight Correction. This feature didn't seem to work properly for this test subject, as there are slightly more clipped highlights with Highlight Correction On versus Off. The Pentax K-5 boosted ISO to 160, so shadow detail is slightly noisier.

Here are the results with our Far-field House shot. Again, we see a lightening of shadows as the Shadow Correction setting is increased, but there is also a slight increase in highlight clipping. Highlight Correction didn't seem to work with this scene either, though there weren't many highlights clipped in the first place.

HDR Capture
The Pentax K-5 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 when using the D-Range option. (In fact, it can reduce shadow noise by combining shadows from the overexposed shot.) There are six HDR settings available, three more than the K-7: Off (default), Standard, Auto and Strong 1/2/3. (The K-7 has just one "Strong" setting, and no "Auto" setting.)

As you can see from the above images, HDR Standard and Auto settings worked quite well on our Far-field House test shot, reducing both clipped highlights and bringing out shadow detail. The Strong settings were a bit too much for this scene, resulting in very flat and unnatural looking images with reduced saturation. In addition to the new levels compared to the K-7, the K-5 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.

Low light. As expected, the Pentax K-5 performed 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. The K-5's metering system struggled a bit with getting the exposure correct at the lowest levels though, so we used manual exposure for these shots. Color balance with Auto white balance had a slightly cool bias at lower ISOs that shifted to a magenta cast at some of the very high ISOs and lower light levels. Noise was quite low up to ISO 1,600, and even a higher ISOs, there's still a lot of detail to work with when high ISO NR is set to "Off". As mentioned previously, the Pentax K-5 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. There are a number of hot pixels visible starting at ISO 400 at lower light levels (in addition to the cluster visible in good lighting), and the number increases at higher ISOs. We did not detect any significant banding issues.

The Pentax K-5's phase-detection autofocus system was only able to focus on the subject down to just below the 1/4 foot-candle light level with its AF assist light turned off, which is below average for an SLR. It was however able to focus in total with the focus assist lamp enabled. In Live View mode with contrast-detect autofocus, the K-5 was only able to focus down to almost the 1/2 foot-candle, which is also not as good as most SLRs with Live View. (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 do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality

ISO 80/100/200 looks very crisp at 24 x 36 inches, with good color and detail.

ISO 400 images look great at 20 x 30 inches, with little loss of detail.

ISO 800 prints are quite good at 16 x 20 inches.

ISO 1,600 loses detail in our red leaf swatch, but other areas still look good at 11 x 14 inches.

ISO 3,200 looks better printed at 8 x 10 inches, with some luminance noise in the shadows, but still good. 

ISO 6,400 images are usable for less critical applications at 8 x 10 inches, but the luminance noise warrants a reduction to 5 x 7, where the whole image looks tighter and sharper. Detail in reds is quite soft now.

ISO 12,800 shots are way too noisy for 5 x 7 inch prints, but come right back to acceptable quality when printed at 4 x 6.

ISO 25,600/51,200 images are not usable and best avoided.

Overall, a good performance for the Pentax K5. It retains excellent detail for quite a run of large print sizes, which makes for easy cropping from lower ISO settings and the ability to squeeze a 4 x 6 out of ISO 12,800, great for indoor low-light snapshots.

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.)