Pentax K-30 Exposure
Pentax K-30 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 for larger versions.|
Saturation. The Pentax K-30's default image tone setting of "Bright" pushes most colors by quite a bit at base ISO, especially blues, greens, and reds. 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-30 were a touch yellow using auto white balance in our test shots, 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-30's mean "delta-C" color error of 7.81 after correction for saturation is a little below average for an SLR 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-30 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.
|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 K30OUTBSATx.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-30's Auto White Balance had a difficult time with the very warm color balance 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-30 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 colors with very good exposure and good highlight/shadow detail preservation.
|Manual White Balance,
|Auto White Balance,
The Pentax K-30 handled tough outdoor lighting under harsh sunlight fairly well, producing bright colors with good exposure. Default contrast was 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 generally pretty clean. +0.3 EV exposure compensation was required to keep the model's face reasonably bright, which is 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 our "Outdoor" Portrait shot here. Our Far-field shot was slightly underexposed at 0 EV, but again with bright, punchy color. Very few highlights were clipped, but there were some very deep shadows, though shadow detail was quite good. Good results overall here.
Very high resolution, ~2,100 lines of strong detail from JPEGs, a little higher from converted raw files.
|Strong detail to
2,100 lines horizontal
|Strong detail to
2,100 lines vertical
|Strong detail to
2,250 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 2,100 lines per picture height in both the horizontal and vertical direction in JPEGs. Complete extinction didn't occur until around 2,600 lines in both directions. We were able to resolve a little more with an Adobe Camera Raw conversion, about 2,250 lines of resolution in the horizontal direction and about 2,200 in the vertical, and complete extinction of the pattern was extended beyond 3,600 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
Sharp images overall, though moderate edge-enhancement on high-contrast subjects. Minor noise suppression visible at base ISO.
Sharpness. The Pentax K-30 produced sharp images with very good detail at default settings. Some 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 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 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. Good performance here, but we'd prefer default noise reduction to be a little less aggressive. 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-30 does a pretty good job at capturing lots of detail, but more detail can 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 6.7, then sharpened in Photoshop. For the Pentax K-30's raw files, we found good results with strong but tight 400% 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 extracts quite a bit more fine detail that wasn't present in the JPEGs, but there's also a touch more noise visible (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
Very good handling of noise versus detail to ISO 1,600.
|Noise Reduction = Auto (Default)|
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1,600||ISO 3,200|
|ISO 6,400||ISO 12,800||ISO 25,600|
The Pentax K-30's images are 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 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", but fine detail is still generally 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. As expected, images at ISOs 12,800 and 25,600 have much stronger luminance noise and much less detail than those at lower sensitivity levels, while chroma noise in the form of purple and yellow blotching is more obvious, especially at ISO 25,600.
Default noise reduction seems stronger than the K-5's, but otherwise image quality appears to be similar which is to say very good. Note that these images were shot using the Pentax K-30 "Auto" noise reduction setting. The Pentax K-30 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 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-30 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-30's contrast adjustment also did a good job of decreasing overall contrast though it did impact saturation; see the section below.) The +0.3 EV exposure did the best job here, as we thought that too many highlights were lost at +0.7 and 0 EV was too dim in the face. Some highlights were blown in the model's shirt and bright flowers at +0.3 EV, though, while very good detail was preserved in the shadows with low levels of noise. Very deep shadows have some abrupt tonal transitions which can lead to posterization if trying to boost shadows too much, though nothing really to be concerned with unless you are doing trying to recover the deepest shadows in post processing (better to shoot in raw mode then). Note that these shots were captured with the Pentax K-30'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-30 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 10.4 f-stops of total dynamic range (albeit with some widely spaced steps in the shadows as previously mentioned), and 7.71 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-30 actually scored a bit better with its JPEG producing 7.71 versus 7.22 f-stops at the highest quality level, and almost identically at 10.4 vs 10.5 f-stops total dynamic, though some of that improvement in the high quality number is due to slightly stronger default noise reduction. 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. As can be seen, the score at the highest quality level increased over two f-stops from 7.71 to 9.86 f-stops, while total dynamic range increased just over two f-stops from 10.4 to 12.5. These results are good, though not as good as the K-5 which managed 10.2 f-stops at the highest quality level. (And keep in mind the K-5 offers slightly lower minimum ISO of 80, which produces a bit less noise.) It's also 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-30'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-30 did a really excellent job of bringing nice detail out of the shadows as well as preserving 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 shot were noticeably less saturated.
|Contrast Adjustment Examples|
The series of shots above shows results with several different contrast adjustment settings, showing the minimum step size around the default, as well as both extremes. 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.
The Pentax K-30 offers three Shadow Correction levels (Low, Medium, and High, plus Off and Auto) as well as one Highlight Correction level (Auto/On/Off). Auto is the default setting for both. 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.
Outdoor Portrait D-Range Examples (+0.3 EV)
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 little change with the Auto setting. 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 it raised ISO to 200. Auto decided no highlight correction was necessary, producing results practically identical to Off.
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 there weren't many highlights clipped in the first place, so again, the Auto setting had little effect.
The Pentax K-30 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. (In fact, it can reduce shadow noise by combining shadows from the overexposed shot.) There are four HDR settings available: Off (default), Auto, and HDR 1/2/3 providing +/-1 EV, +/-2 EV and +/-3 EV exposure ranges respectively.
Far-field HDR Examples
The Auto HDR setting 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 the ghosting that occur when subjects are moving between exposures, such as the flag and leaves in the shots above. The K-30 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.
Low Light. The Pentax K-30 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. 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-30 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 a touch 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 or banding, and only a hint of heat blooming can be seen in the bottom right at the highest ISO when NR turned "Off."
The Pentax K-30's phase-detection autofocus system was able to focus on the subject down to the 1/8 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-30's contrast-detect autofocus was able to focus down to just above the 1/4 foot-candle level.
(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.) Thanks to their larger sensors, compact system cameras like the Pentax K-30 tend to do better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects. (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.)
Impressive 24 x 36 inch prints at ISO 100/200; good 8 x 10s at ISO 3,200; ISO 12,800 makes a good 4 x 6.
ISO 100/200 shots look quite good printed at 24 x 36 inches. Prints look better than the Canon T4i, despite its higher resolution, mostly because the K-30 by default is using less noise suppression at low ISOs.
ISO 400 shots look better at 20 x 30 inches, as the softening is a little too much at 24 x 36.
ISO 800 shots are usable at 20 x 30, but luminance noise shows up in the shadows, and detail in reds is a bit smudgy. As a result, we prefer the 16 x 20 inch prints.
ISO 1,600 images have sufficient detail for 11 x 14 inch prints, all except for our red swatch (a common outcome).
ISO 3,200 images are decent at 11 x 14, but noise is a little strong, so we preferred the 8 x 10 inch prints.
ISO 6,400 shots are good at 5 x 7, with only minor grain apparent in shadowy areas.
ISO 12,800 shots look good at 4 x 6, slightly noisy, but not bad.
ISO 25,600 prints are not usable.
Overall, the Pentax K-30 does a lot with its 16-megapixel sensor. It produces great 8 x 10 inch images at ISO 3,200 and even 12,800 is good for a 4 x 6.
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-30 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-30 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!
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