Samsung NX20 Exposure
Samsung NX20 Image Quality
Saturation & Hue Accuracy
Realistic saturation levels with good overall hue accuracy, though some issues with manual white balance.
|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 Samsung NX20 produces images with saturation levels that are more accurate than most cameras when using default settings. The NX20 pushes a number of colors but just a bit, less than we're used to seeing. Default saturation is 107.5% (only 7.5% oversaturated) at base ISO, which is lower than most competitors, but not dramatically so. (The recent average remains at about 110%.) Saturation falls gradually as ISO rises, reaching 100% at ISO 3,200, but there's a blip to 104.1% at ISO 6,400 before returning to 100.2% at maximum ISO. You can of course tweak saturation to your liking, or choose a different color mode. 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. The Samsung NX20 did well with Caucasian skin tones, rendering them with a pinkish tint that is realistic-looking. Darker skin tones had a slightly orange push, but overall skin tones were quite pleasing in simulated daylight, as long as you don't adjust contrast. 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 Samsung NX20 shifts yellow toward green and red toward orange slightly, and orange toward yellow moderately, but other shifts in color were relatively minor; even the cyan to blue shift we normally see is very small. Mean "delta-C" color error at base ISO is 4.19 after correction for saturation, which is pretty good, better than average. White and grays are shifted slightly toward green at lower ISOs despite using manual white balance, though, giving some shots like our Still Lifes and Indoor Portraits a greenish cast. Oddly, white balance improves as ISO rises. Hue is "what color" the color is.
Samsung NX20 lets you adjust image saturation (as well as contrast and sharpness) in nine steps. As can be seen below, the saturation adjustment was quite effective and covers a useful range, but it does impact contrast somewhat, at least for some colors. This is not uncommon though, as it's pretty tricky not to impact contrast when adjusting saturation so much.
|Saturation Adjustment Examples|
The table above shows results with every other saturation setting, including the default and the two extremes. Click on any thumbnail above, then click again 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
The Samsung NX20 struggled with white balance here, producing results that are too warm or cool. Average amount of positive exposure compensation required.
|Auto White Balance
|Incandescent White Balance
|Manual White Balance
Indoors, under normal incandescent lighting, color balance is a bit too warm with the Auto setting, with a reddish cast. The Incandescent setting resulted in a fairly strong green cast, and the 2,600 Kelvin setting produced a strong blue-green tint. Manual white balance produced the best results, though with a bias toward yellow-green. The Samsung NX20 required an average amount of positive exposure compensation here, at +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.)
Somewhat cool colors with slightly high contrast under harsh lighting. Better than average exposure accuracy.
|Manual White Balance,
|Auto White Balance,
The Samsung NX20 produced pleasant pinkish skintones when set to Manual white balance in our "Sunlit" Portrait test, which we prefer to the slightly pale skintones from the Auto setting. The NX20 required +0.3 EV exposure compensation to keep facial tones bright on the mannequin. The average for this shot is about +0.7 EV, so that's pretty good. Default contrast is a little high, though, so quite a few highlights in her shirt and flowers are blown. The NX20 did a pretty good job with our Far-field shot, with very good exposure accuracy, though colors are slightly cool and muted. The Samsung NX20 preserved all but the brightest highlights here, though it did generate some very dark and posterized shadows.
Very high resolution, 2,200 to 2,300 lines of strong detail in JPEGs, about the same from ACR converted raw files.
|Strong detail to
2,300 lines horizontal
|Strong detail to
2,200 lines vertical
|Strong detail to
2,300 lines horizontal
ACR processed SRW
|Strong detail to
2,200 lines vertical
ACR processed SRW
In-camera JPEGs of our laboratory resolution chart at the highest quality setting reveal sharp, distinct line patterns to about 2,300 lines per picture height in the horizontal direction, and to about 2,200 lines per picture height in the vertical direction. Complete extinction of the pattern doesn't occur until a little over 3,400 lines in the horizontal direction, and about 3,300 lines in the vertical. An Adobe Camera Raw conversion of a matching raw file showed very similar resolution along with a lot more color moiré, so the NX20 does a great job at extracting maximum high-contrast resolution at base ISO. 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 good sharpness and detail overall, though with some visible edge-enhancement artifacts on some high-contrast subjects. Low levels of noise suppression generally leaves excellent detail at base ISO.
|Very good definition of
though with some visible
|Subtle detail: Hair
Noise suppression tends to blur
detail in areas of subtle contrast but
the NX20 does better than most here.
Sharpness. The Samsung NX20 captures sharp, detailed images, though some edge enhancement artifacts are visible on high-contrast subjects such as the sharpening halos around the thicker branches and pine cones in the crop above left. Fine detail such as the smaller twigs and pine needles show very little edge enhancement, yet show excellent detail, likely the result of a fairly weak low-pass filter and a light-handed approach to noise reduction at base ISO. Overall, very good results here. Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.
Detail. The crop above right shows relatively minor noise suppression in the darkest areas of the model's hair, as most individual strands of hair are well defined except in very low contrast areas. Overall, detail is very good for an APS-C sensor at base ISO, especially one with 20 megapixels of resolution. Excellent results 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.
There are however what look to be aliasing artifacts and "jaggies" in areas of fine vertical detail and high local contrast, such as in the strands of hair on the model's forehead at lower ISOs (see ISO 100 crop at right). We've seen similar artifacts in images from other cameras, especially Canon consumer SLRs, so they're not that unusual. The aberrations are very subtle to be sure, but they're something to be aware of if you plan to make very large prints of similar subject matter. They also appear in raw files processed with Adobe Camera Raw, a further indication that the NX20's low pass (anti-aliasing) filter isn't very strong.
Raw vs In-Camera JPEGs
As noted above, the Samsung NX20 produces sharp, detailed in-camera JPEGs. Let's see how the bundled raw converter and Adobe Camera Raw perform on the same image:
In the table above, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking on the link will load the full resolution image.
Here, you can see that the Samsung Raw Converter 4 conversion at default settings resulted in an image that is quite a bit softer than the in-camera JPEG. (Normally, manufacturer provided converters produce results very similar to in-camera JPEGs at default settings, but Samsung Raw Converter 4 is a rebadged version of SilkyPix, so it probably doesn't implement the exact same image processing algorithms as the camera.) The bundled raw converter has quite a few features and presets, but we found that turning off sharping in the editor itself, and then applying a strong Unsharp Mask of 300% with a radius of 0.3 when generating the output JPEG produced better results. Even sharpened, the camera produced better fine detail than the bundled converter, as the software's noise reduction tends to flatten fine detail. The Adobe Camera Raw conversion (which was sharpened in Photoshop also using USM of 300% with a radius of 0.3) revealed slightly better detail than the camera JPEG, though not a whole lot, but there are less noticeable sharpening artifacts. The ACR conversion also shows more noise in flat areas, which is often the case. One of the advantages of shooting raw is being able to decide for yourself the optimum trade-off between detail and noise, especially when the camera provides very limited control over noise reduction like the NX20. At low ISOs, though, the Samsung NX20 generally does a great job at extracting the excellent detail captured by its 20-megapixel sensor, even if default sharpening is a bit high.
ISO & Noise Performance
Very good detail vs noise tradeoff to ISO 1,600, though strong noise reduction and high chroma noise at higher ISOs.
Default High ISO Noise Reduction (On)
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1,600||ISO 3,200|
|ISO 6,400||ISO 12,800|
The Samsung NX20's light-handed approach to luminance noise reduction at lower ISOs leaves a lot of fine detail intact up to ISO 400, though some luminance noise is visible even at base ISO. At ISO 800, luminance noise reduction is noticeably stronger smudging some hairs together, but fine detail is still very good. Some chroma noise is visible in the shadows, though, and this gets worse at higher ISOs. Naturally, luminance and chrominance noise is higher at ISO 1,600, but a lot of fine detail remains intact. Chroma noise becomes quite strong at ISO 3,200 though, with small but noticeable clouds of color blotching, as well as an obvious drop in detail from more aggressive noise reduction. This of course worsens at ISO 6,400 where fine detail is smudged away to give a stippled effect, while chroma noise is spread out into larger, brighter color blotches. At 12,800, chroma noise is very high with more obvious purple, green and orange color blotches, as well as stronger luminance noise.
Overall, though, a better performance than the NX200 at higher ISOs where the NX200's aggressive noise reduction blurred-away more detail. Compared to recent APS-C competitors, the NX20 does well at lower ISOs, but chroma noise isn't handled as well in higher ISO JPEGs. As always, see the Print Quality section below for maximum recommended 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, Olympus Zuiko 55mm f/2.0 for Four Thirds and Micro Four Thirds bodies). For the Samsung NX20, we used the very sharp 85mm f/1.4 ED SSA NX. 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.
Red Channel NR. Although the Samsung NX20 does better at preserving fine detail at high ISOs than the NX200, it still struggles with the low-contrast detail in our red leaf cloth at low ISOs. And like the NX200, the NX20 doesn't provide much control over noise reduction either: only Off and On options for both High ISO NR and Long Term NR are offered. The user manual doesn't mention which ISO setting High ISO NR kicks in at, but from our Still Life ISO/NR series, it looks like it's at least ISO 1,600, so turning it off is no help at lower ISOs. Have a look at the crops below to see how much subtle detail is lost in the red leaf pattern to noise reduction even at ISO 100:
|In-Camera JPEG, ISO 100
High ISO NR = "Off"
|Converted Raw, ISO 100
Adobe Camera Raw, Default NR
The above crops compare an in-camera JPEG (left) to an ACR converted raw file (right). Both shots were taken at ISO 100, and the converted raw file has default noise reduction applied.
Extremes: Sunlit, dynamic range, and low light tests
Very high resolution with good detail, but somewhat high default contrast and limited dynamic range. Good low-light performance, though Auto white balance struggled.
|0 EV||+0.3 EV||+0.7 EV|
Sunlight. The Samsung NX20 struggled a bit with the deliberately harsh lighting of this test, as do a lot of cameras. Quite a few highlights are clipped in the white shirt and flowers, while some shadows are still quite dark, though noise in shadows is actually pretty good (apart from the posterization mentioned in very deep shadows). We preferred the +0.3 EV exposure overall, because the exposure of skintones in the face is better than 0 EV and +0.7 EV has too many clipped highlights. Depending on the photographer, you could lean one way or the other. Advanced users will want to shoot darker, to hold highlight detail. For those NX20 owners that are going to want to just print an image, the +0.3 EV image would probably produce the best-looking print with little or no tweaking. The bottom line though, is that the NX20 struggled in harsh lighting, producing either a slightly dim face with better highlight retention in the shirt, or a well-exposed face with more blown highlights in her shirt and flowers.
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.)
The Samsung NX20's contrast adjustment wasn't much help in taming blown highlights in this harsh lighting.
|Contrast set to lowest,
|Contrast set to lowest,
At its lowest contrast setting, the Samsung NX20 didn't do much better at preserving highlight detail. However, at the lowest contrast setting midtones and shadows were boosted quite a bit. The odd-looking coloration in the mannequin's face is due to drop in saturation where contrast was reduced, which is an unfortunate interaction.
|Contrast Adjustment Examples|
The table above shows results with every other contrast setting, including the default and two extremes. It's pretty hard to evaluate small differences in contrast on small thumbnails like these, click on any thumbnail to go to the full-size image. It's nice that Samsung offers such a wide range of settings, but as mentioned previously, the NX20's contrast adjustment helps very little with strong highlights, working mostly in the midtones and shadows. Also mentioned previously, there is some interaction with saturation, most noticeable in the facial tones and flowers at the lower contrast settings.
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.)
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. A full discussion of all the data Imatest produces is really beyond the scope of this review: Visit the Imatest website for details of what the program measures, how it performs its computations, and how to interpret its output.
JPEG. The graph at right (click for a larger version) was generated using Imatest's dynamic range analysis for an in-camera NX20 JPEG file with a nominally-exposed density step target (Stouffer 4110). At default settings and ISO 200 (we found total dynamic range was optimal at ISO 200, not ISO 100), the graph shows 9.7 f-stops of total dynamic range, with 8.75 f-stops at the "High" quality level. Roll-off at the highlight end of the curve is fairly gradual, but at the low end, some steps are spread out, indicative of a tendency of the deepest shadows to break up into discrete levels, which can be seen when manipulating levels in our outdoor shots. Still, these scores aren't bad for a camera JPEG. Compared to the NX200, the NX20 scored better at the "High" quality level (8.75 vs 7.62 f-stops), but total dynamic range was quite a bit lower (9.7 vs 10.5 f-stops). 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 (.SRW) file, processed with Adobe Camera Raw. The Samsung NX20's processed raw file actually scored lower than the matching in-camera JPEG at the highest quality level, with a decrease from 8.75 f-stops to 7.88, however total dynamic range increased significantly from 9.7 to 12.1 f-stops, though response at the shadow end of the curve is still not that well-behaved. Compare that to the NX200, which scored a nearly identical 7.89 f-stops at the highest quality level, but a lower 11.2 f-stops in total dynamic range. It's worth noting here that Adobe Camera Raw's default noise reduction settings usually reduce overall noise relative to the levels in the in-camera JPEG, which tends to boost the dynamic range numbers for the High Quality threshold. That wasn't the case for the NX20 (compare the noise plots in the bottom left of the graphs above).
Smart Range is Samsung's name for their dynamic range enhancement technology. It works similar to Canon's Highlight Tone Priority, preserving highlights at the expense of noisier shadows.
Despite the apparent brightness, very few highlights were clipped with Smart Range set to On in our "Sunlit" Portrait shot above. Smart Range doesn't affect levels in the shadows much, just boosting saturation, but because it uses ISO 200 there's more noise. The NX20 attempts to compensate by applying stronger noise reduction, which leads to some loss of detail in the shadows.
Far-field Smart Range Example
Here, you can see Smart Range at work with our Far-field shot, reducing highlights in the clock tower and pillars, but again, deep shadows are less detailed due to stronger noise reduction.
Low Light. The Samsung NX20 performed reasonably well in our low light test. The NX20's slowest shutter speed of 30 seconds combined with the kit lens' maximum aperture of f/3.5 resulted in slightly dim (but still usable) images at the lowest light level we test at (1/16 foot-candle) at ISO 100. Noise is well controlled up to ISO 800, though at higher ISOs there are moderate amounts of fine luminance noise and increasing chroma noise.
Auto white balance did a reasonable job here at higher light levels, producing fairly neutral if slightly cool color balance, though there's sometimes a blue-green bias at lower light levels at ISOs up to 800. Interestingly, the color shift is not present when High ISO NR and Long Term NR are turned Off (right-most column). Some horizontal banding is visible at very high ISOs (starting at ISO 3,200), but that's not unusual. We didn't notice any issues with hot/dead pixels except when NR was turned Off, where they're expected.
The Samsung NX20's autofocus system was only able to focus down to about the 1/4 foot-candle light level unassisted with the 18-55mm kit lens, which isn't very good. Oddly, the NX200 was able to focus down to almost the 1/16 foot-candle using the same lens under the same conditions. The NX20 was however able to focus in complete darkness with its built-in focus assist lamp enabled.
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 phase-detect AF systems, digital SLRs tend to do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects. The NX20 uses contrast-detect autofocus, as is found in most point & shoot cameras, so its low-light focusing ability is less than that of most SLRs with phase-detect systems. That said, though, the larger, more sensitive pixels of the NX20's sensor do better under dim lighting than do the tiny pixels of most point & shoots, (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.)
Very good 24 x 36-inch prints from ISO 100; ISO 1,600 shots look good at 13 x 19; ISO 12,800 shots make decent 4 x 6-inch prints.
ISO 200 images are quite good at 20 x 30 inches, with good color and detail.
ISO 400 images print well at 20 x 30 too, though there is some faint luminance and chroma noise in the shadows. We still call them good.
ISO 800 shots are usable at 20 x 30, but look better at 16 x 20 inches.
ISO 1,600 prints are pretty good at 13 x 19, but blotchy luminance and chroma noise in the shadows is noticeable even from arm's length.
ISO 3,200 shots look better at 8 x 10, but dark colors continue to be marred by the blotchy noise, lightening darks such that it reduces contrast. This effect is diminished when printed at 5 x 7.
ISO 6,400 shots also look good at 5 x 7.
ISO 12,800 shots make good 4 x 6-inch prints from arm's length, but darks are affected by noise, important to note if you're printing a nighttime image.
Overall, the NX20's printed results are quite good. Image quality drops quickly from 1,600 to 3,200, though, something we've seen in past Samsung CSCs. This is quite a bit better, though, so we're happy to report Samsung has improved its image processing above ISO 1,600.
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 the Canon 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 Samsung NX20 Photo Gallery .
Not sure which camera to buy? Let your eyes be the ultimate judge! Visit our Comparometer(tm) to compare images from the Samsung NX20 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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