Pentax K-70 Exposure

Saturation & Hue Accuracy
High mean saturation, with average hue accuracy.

Saturation. The Pentax K-70's default image tone setting of "Bright" pushes most colors by quite a bit at base ISO, especially blues, dark greens, dark reds and purples. Mean saturation at ISO 100 is 119.9% or 19.9% oversaturated. That's about 10% higher than most other brands at default settings. Overall, colors are very bright and punchy, a trait we've come to expect from Pentax. Mean saturation remains higher than average throughout most of the ISO range, peaking at 120.3% at ISO 25,600, and falling to a minimum of 111.5% at the maximum ISO of 102,400. You can of course always select a different image tone preset and/or turn down saturation and contrast settings 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-70 were a touch yellow using Manual white balance in our test shots, however Auto white balance produced a slightly 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-70's mean "delta-C" color error of 5.41 after correction for saturation at ISO 100 is about 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.) Mean color error peaks at a maximum of 5.82 at ISO 12,800, though that's quite good for such a high ISO. Hue is "what color" the color is.

Exposure and White Balance

Indoors, incandescent lighting
Very warm results with Auto white balance, but good color with Incandescent and Manual white balance settings. Average exposure compensation required.

The Pentax K-70's Auto white balance setting 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 fairly strong red-orange tint when using the default "Strong" Correction option. The"Subtle" Correction setting produced even warmer results, as expected. Results with the Incandescent setting are actually pretty good, though, just slightly warm. The Manual setting produced the most accurate color balance, though just a touch cool. Note that a Kelvin setting is available, as well as Color Temperature Enhancement (CTE) white balance option which exaggerates the temperature of ambient light. The Pentax K-70 required +0.3 EV exposure compensation for a good exposure, which is average 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.

Outdoors, daylight
Very bright, slightly cool colors with about average exposure accuracy.

The Pentax K-70 handled tough outdoor lighting under harsh sunlight fairly well, producing very bright though slightly cool colors. +0.7 EV exposure compensation was required to keep the mannequin's face bright, which is about average for this scene. Skin tones were just a touch warm and yellow using Manual white balance, so we preferred Auto white balance for our "Sunlit" Portrait shot here. Default contrast is quite high, though, resulting in quite a few harshly clipped highlights in the mannequins's shirt and some of the flowers, as well as some lost shadows below the flowers and in the background, though all but the deepest shadows were quite clean for an APS-C sensor. Our Far-field shot was slightly overexposed at default 0 EV, leading to some blown highlights, again with punchy, slightly cool color. Although quite a few highlights are blown, there are still some very dark shadows thanks to the high contrast. Shadows are detailed and fairly clean for an APS-C sensor, though very deep shadows are monochromatic. Still, good results overall here.

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

Native Resolution
~2,700 lines of strong detail from JPEGs, about the same from converted RAW files.

Our laboratory resolution chart reveals fairly sharp, distinct line patterns down to about 2,700 lines per picture height in the horizontal direction, and to about 2,700 lph in the vertical direction in a best quality JPEG, though some aliasing can be seen at around 2,300 - 2,400 lph. Complete extinction of the pattern didn't occur until just before 3,300 lines in both directions. An Adobe Camera Raw conversion yielded the same numbers, though individual lines were more crisp up to the same resolution, and complete extinction of the pattern was extended up to the 4,000 line limit of our chart. The ACR processed RAW images do however show a lot more color moiré, as they often do. (Note that AA Simulation was set to its default of off, for maximum resolution.) 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.

Pixel Shift Resolution Mode
~2,850 lines of strong detail from JPEGs (ACR does not support K-70's PSR mode as of this writing).

The Pentax K-70's Pixel Shift Resolution mode yielded slightly higher resolution from in-camera JPEGs at about 2/850 lph horizontally and 2,850 lph vertically, but there were strong aliasing artifacts in the form of moiré patterns starting as early as 2,200 or 2,300 lines. Luminance noise also appears to be higher, as can be seen when looking closely at the white parts of the chart.

Adobe Camera Raw does not yet support the K-70's PSR mode, so we'll do a conversion and add results here after it adds support.

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

Sharpness & Detail
Sharp images with excellent detail, though with moderate edge-enhancement on high-contrast subjects. Minor noise suppression visible at base ISO.

Sharpness. The Pentax K-70 produces sharp images with excellent detail at default settings. Images are somewhat 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 with crisp looking images. 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, and chroma noise appears very low. Some individual strands of hair do show aliasing artifacts in the form of "jaggies", however the K-70's selectable AA filter should help prevent those from occurring when enabled (AA Filter Simulation was disabled 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-70'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 aliasing artifacts, roll over the links in the table below to compare settings:

As you can see above, AA Filter Simulation Type 1 blurs fine detail slightly, while Type 2 offers a slightly stronger effect, which should go a long way to reduce aliasing artifacts and moiré as can be seen in the center of the starburst crop. The crop on the right is a real-world example that shows moiré reduction in the blinds and also a slight reduction overall sharpness. Note that the AA Filter Simulator is not available in burst mode and some scene modes, or during Bulb or HDR capture, and the full effect cannot be achieved at shutter speeds faster than 1/1000s. Pentax has however provided a very useful AA filter bracketing mode, which will take 3 shots with the different AA filter settings in case you're not sure which setting to use, or want to selectively merge different exposures to reduce aliasing in specific areas.

Pixel Shift Resolution
As mentioned above, the Pentax K-70's Pixel Shift Resolution mode captures greater detail with fewer aliasing artifacts. Let's see how it compares to a normal mode JPEG with our Still Life target at base ISO:

As you can see, the Pixel Shift Resolution JPEG (on the right) captures finer detail with fewer aliasing artifacts, though contrast is a little lower. Notice how small details are rendered better in the mosaic crop, and the lack of moiré patterns in the red-leaf swatch. PSR mode does however generate some "fine-grained" but fairly bright luminance noise as seen in the background in the top bottle crop, obscuring some of the subtle texture.

Like the Pentax K-1, the K-70 offers optional Motion Correction in PSR mode, but we found it doesn't always work well, generating combing and ghosting artifacts around moving objects as can be seen in our Far-field PSR image with it enabled. Thus, it's still best to use it for entirely static objects.

For a lot more on Pentax's PSR technology, see our detailed K-3 II and K-1 Pixel Shift Resolution writeups.

RAW vs In-Camera JPEGs
The Pentax K-70 does a great job at capturing lots of fine detail in its normal 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 9.7 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 better with our difficult red-leaf swatch, resolving more of its fine thread pattern which the camera mostly blurred away as noise, as well as producing higher contrast in the leaf pattern. ACR also did a better job with color, rendering the pink fabric closer to reality instead of the more magenta interpretation of the camera, as well as not boosting other colors as much as the camera. Adobe Camera Raw also produced finer detail in the mosaic crop, but left behind more noise, as seen in flatter areas such as in the bottle and background in the first pair of crops. Overall, though, the Pentax K-70 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
Excellent high ISO performance for an APS-C model.

The Pentax K-70's images are very clean and detailed from ISO 100 through 800, with very low chroma noise and just a touch of luma noise becoming more visible in the shadows and darker midtones as ISO increases, accompanied by just a slight increase blurring due to noise reduction. Detail is still very good at ISO 1600, with a tight film-like noise "grain", low chroma noise 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, and chroma noise remains low. ISO 6400 shows stronger luminance noise, though there's still a good amount of usable detail left and chroma noise is well-controlled. ISO 12,800 is quite grainy but chroma noise is still fairly low and there is some usable detail detail left. Image quality at ISO 25,600 and above falls off more quickly, with much stronger luminance noise, and much less detail than at lower sensitivity levels. Chroma noise in the form of yellow and purple blotches starts to become an issue at ISO 25,600 and is pretty bad at the maximum ISO of 102,400.

Overall, though, high ISO noise performance is excellent for a 24-megapixel APS-C camera, especially for one in its price range.

Note that these images were shot using the Pentax K-70 "Auto" noise reduction setting. The Pentax K-70 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.

Extremes: Sunlit, dynamic range, and low light tests
High contrast can lead to blown highlights but shadow detail is excellent. Very good low-light performance, capable of capturing bright images in near darkness.

Sunlight:
The Pentax K-70 struggled a bit in the deliberately harsh lighting in the above test, thanks to its high default contrast. The +0.7 EV exposure did the best job here, as we thought +0.3 and 0 EV were too dim in the face. That led to quite a few blown highlights in the mannequin's shirt and bright flowers at +0.7 EV, 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-70's D-Range control set to "Off."

The good news is that highlights are easily recoverable from the matching DNG RAW file even at +1.0 EV, so the K-70's sensor appears to have very good dynamic range. Also, the K-70's Highlight Correction feature (available at ISO 200 and above) is quite effective at avoiding blown highlights. See below.

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.)

Face Detection
Here, we can see the effect of the Pentax K-70's full Auto mode as well as face detection AF enabled in Live View mode. As you can see from the shots above, full Auto which selected Portrait Scene mode produced a better exposed face and background, however it blew quite a few highlights in the mannequin's shirt. It selected an aperture of only f/3.2 with a shutter speed of 1/250s but kept ISO at 200 and used Auto white balance producing more pinkish skin tones. Face-detection AF mode also improved the exposure versus Aperture-priority without blowing as many highlights, selecting a slower shutter speed of 1/50s versus 1/100s to brighten the image (since the other two exposure variables of aperture and ISO were fixed).

D-Range Settings
The Pentax K-70 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.

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 progressive lightening of shadows and midtones as the Shadow Correction setting is increased, with only a small impact to highlights. And in this case, the Auto setting produced results very similar to the manual Low 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.

Highlight Correction. Highlight Correction worked as expected when highlights are blown, with On and Auto producing virtually identical results here (compare Highlight On or Highlight Auto to D-Range Off), toning highlights down to protect them while keeping shadows and midtones roughly the same. Note that Highlight Correction is not available at ISOs below 200, so this series was shot at ISO 200.

HDR Capture
The Pentax K-70 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 in the K-70: Auto, HDR 1/2/3 providing three blend settings, and Advanced. Each setting has three possible exposure ranges (±1 EV, ±2 EV (default), 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-70.

Mouse-over the links above to compare thumbnails, and click on them to access full-resolution versions. (We used with the default +/- 2EV exposure range.)

The Auto setting worked reasonably well on our Far-field test shot, reducing highlights and bringing out shadow detail while maintaining a natural, non-HDR look. HDR 1 mode produced a relatively realistic image though with an obvious HDR-ish look, HDR 2 produced a stronger HDR effect, HDR 3 resulted in a very unnatural almost cartoonish image, and HDR Advanced produced very strong and ugly 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 although the K-70 does attempt to avoid that..

Interestingly, some earlier Pentax DSLRs like the K-3 supported RAW files in HDR mode, bundling the individual captures into one large file to be processed later by their Digital Camera Utility software which can blend or extract the separate RAW files. However, RAW file support for HDR mode is not supported on the K-70 (but can be easily achieved using individual files and exposure bracketing.)

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.

Unfortunately, DxOMark has not tested the Pentax K-70 yet. We'll revisit and fill in this section once they do.

Low Light. The Pentax K-70 performed well in terms of image quality in our low-light tests, capturing clean, well-exposed images at the lowest light level (1/16 foot-candle) with the lowest sensitivity setting (ISO 100). As you'd expect, noise is higher at ISO 3200 but it appears very well-controlled and fine-grained. Unsurprisingly, the maximum ISO of 102,400 is quite noisy with noticeably less detail and lots of chroma blotching, and is best avoided except perhaps in emergencies.

Color balance with Auto white balance was quite good which isn't always the case, with just a slightly cool bias that becomes slightly cooler as light levels drop.

We did not detect any significant issues with hot pixels, with just a few appearing when noise reduction is minimized and long exposure noise reduction is turned off (right-most column), where you can expect to seem them. Only minor heat blooming can be seen at the highest ISO, along with some very minor horizontal banding (fixed pattern noise) with almost none detectable at base ISO even in very deep shadows.

LL AF: The Pentax K-70's phase-detection autofocus system was able to focus unassisted on our low-contrast AF test target down to the 1/16 foot-candle light level (-2.0 EV) using an f/2.8 lens, which is quite good. And with our new high-contrast AF target, the K-70 was able to autofocus down to -4.5 EV, which is excellent for its class. The K-70 has an AF assist lamp which will let you autofocus in complete darkness, as long the subject is within range and has sufficient contrast. The K-70 couldn't autofocus as low in Live View mode, only able to focus down to about 1/4 foot-candle (-0.3 EV) on our low-contrast target, and to just below 1/16 foot-candle (-2.3 EV) with our high-contrast AF target, but that's not bad for a DSLR in Live View mode.

(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-70 do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality
Terrific 30 x 40 inch prints at ISO 100/200; a good 13 x 19 inch print at ISO 1600; a nice 5 x 7 inch print at ISO 6400.

ISO 100/200 both provide terrific printed images at 30 x 40 inches and larger -- as large as you want to print until the resolution tops out. These images showcase crisp fine detail and rich color reproduction, with a nice vibrance throughout the image.

ISO 400 prints at 30 x 40 inches are fine for less critical applications and wall display prints. For more critical applications we recommend 24 x 36 inches as the optimal large size here, and this size provides an excellent printed image all around.

ISO 800 images pass our good seal at 16 x 20 inches, although there is a mild amount of noise present in flatter areas of our test target at this size, and most contrast detail is now gone in our tricky red-leaf swatch. Larger prints here may be OK for less critical applications, but overall noise levels prevent us from awarding them our good seal.

ISO 1600 produces a 13 x 19 inch print that passes our good rating. All contrast detail is now lost in our red-leaf swatch, but otherwise the noise levels are fairly well-controlled for this ISO at this size, with plenty of fine detail remaining.

ISO 3200 prints just pass our good seal at 11 x 14 inches. These prints exhibit similar issues as found in the 13 x 19 inch prints at ISO 1600, but general color and fine detail is still good here. For most critical applications, we recommend remaining at 8 x 10 inches and under here.

ISO 6400 yields 8 x 10 inch prints that are certainly fine for less critical applications, but there's simply too much overall softening apparent in certain areas of the print to pass our good rating. A size reduction to 5 x 7 inches does the trick for achieving a generally good overall print.

ISO 12,800 images at 5 x 7 inches are similar to the 8 x 10's at ISO 6400 -- good for less critical applications but not quite up to our good standard due to issues with softness and a mild muting of colors overall. The 4 x 6's here are fine for most purposes, so we can call them good here.

ISO 25,600 produces a 4 x 6 inch print that almost passes our good grade, and you may be able to get away with them for less critical applications.

ISO 51,200/102,400 settings do not provide usable prints and we recommend avoiding these settings for most printing purposes.

The Pentax K-70 is an entry-level camera that offers print quality that is markedly above typical entry-level results. Base ISO and ISO 200 prints are stunning in their fine detail, thanks in large part to the lack of an optical low-pass filter, and the camera is capable of providing usable prints a good ways up the ISO spectrum. In general, as with most cameras these days in the APS-C world, we recommend remaining at ISO 3200 and below for your critical printing needs, especially for anything up to 8 x 10 inch prints. Moving to ISO 6400 and higher simply allows too much noise and general softening to enter the picture, but you can expect very solid results from this camera in the print quality department at ISO 3200 and below.