Nikon Coolpix A Image Quality
Saturation & Hue Accuracy
Good saturation levels and average hue accuracy.
|In the diagram above, the squares show the original color, and the circles show the color that the camera captured. More saturated colors are located toward the periphery of the graph. Hue changes as you travel around the center. Thus, hue-accurate, highly saturated colors appear as lines radiating from the center. Mouse over the links to compare ISOs.|
Skin tones. The Nikon Coolpix A's Caucasian skin tones look just about right when using manual white balance in simulated daylight, with a subtle pink cast. A very good job 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 Nikon Coolpix A does shift cyan toward blue, red toward orange, and light green toward yellow, but shifts are relatively minor. (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.) With an average "delta-C" color error at base ISO of 4.92 after correction for saturation, overall hue accuracy is about average, and actually improves slightly as ISO rises. Hue is "what color" the
The Nikon Coolpix A has a total of seven saturation levels available, three above and three below the default saturation, plus an Auto setting. This covers a pretty wide range of saturation levels, about as wide a range as you're likely to find photographically relevant, apart from special effects that are arguably better achieved in software. The fine steps between settings mean it's easy to program the camera to just the level of saturation you prefer. Saturation also doesn't impact contrast, which is ideal but not always the case.
|Saturation Adjustment Examples|
The table above shows results with several saturation settings, see the Thumbnails index page for more (look for the files named Coolpix AOUTBSATx.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
Good color with the Manual white balance setting, but warm results with Auto and Incandescent. About average positive exposure compensation required.
|Auto White Balance
|Incandescent White Balance
|Manual White Balance
Indoors, under normal incandescent lighting, color balance is too warm and reddish-orange with the Auto white balance setting. The Incandescent setting is also too warm, this time with a yellowish cast. The Manual setting by far produced the most accurate results, perhaps just a hint cool. The Nikon Coolpix A 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.
Very good handling of exposure and color, though default contrast is a bit high.
|Manual White Balance,
|Auto White Balance,
The Nikon Coolpix A handled tough outdoor lighting under harsh sunlight pretty well, producing good overall color and exposure. We preferred Manual white balance for our "Sunlit" Portrait shot, as Auto produced skin tones that were a little too warm and yellow. +0.3 EV exposure compensation was required to keep the mannequin's face reasonably bright, which is a bit less than the average of +0.7 EV required for this scene, although +0.5 EV would have likely been ideal given the somewhat high contrast. The far-field shot is just slightly underexposed at 0 EV, so there are some dark shadows but almost no highlights were blown. Color looks good as well, just a touch on cool side.
Very high resolution, ~2,200 to 2,300 lines of strong detail from JPEGs, a little higher from ACR processed RAW files.
|Strong detail to
2,200 lines horizontal
|Strong detail to
2,300 lines vertical
|Strong detail to
2,300 lines horizontal
ACR processed RAW
|Strong detail to
2,300 lines vertical
ACR processed RAW
Our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,200 lines per picture height in the horizontal direction, and to about 2,300 lines in the vertical direction. Complete extinction of the pattern didn't occur before the 4,000 line limit of our chart in both directions. We were able to do a little better with NEF files processed through Adobe Camera Raw, with the horizontal direction resolving slightly higher at about 2,300 lines per pixel height. As usual, color moiré is more evident in the converted RAW files, though camera JPEGs show some significant color moiré as well, which is no surprise given the lack of an OLPF. 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 detail for the pixel count, though images are a touch softer than expected at default settings. Minimal noise suppression visible at base ISO.
Sharpness. The Nikon Coolpix A produces images with very good detail, though default sharpening is a bit conservative (with perhaps some anti-aliasing processing being applied), resulting in images that are a touch soft despite the lack of an OLPF (Optical Low Pass Filter). Only minor edge enhancement artifacts are visible on high-contrast subjects such as the small halos around the branches and pine cones in the crop above left. 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 only minimal detail loss due to noise suppression, as the darker areas of the model's hair show fairly good 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. Still, very good 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.
Raw vs In-Camera JPEGs
As noted above, the Nikon Coolpix A delivers JPEGs with great detail for the resolution right out of the box, though images are a touch softer than expected. Improved detail and sharpness can often be obtained from carefully processing RAW files, without additional 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. Examples include in-camera Fine JPEG, a NEF RAW file processed through Nikon's ViewNX 2 software using default settings, and the same RAW file processed with Adobe Camera Raw 7.4, then sharpened in Photoshop. We found that fairly light sharpening of 200% unsharp mask with a radius of 0.3 pixels really made details pop in the Nikon Coolpix A's NEF files.
As you can see, results from a RAW file converted with Nikon's ViewNX 2 software are very similar to the in-camera JPEG (perhaps just a touch softer), and the software wasn't really able to extract more detail. Adobe Camera Raw was able to produce a much crisper image with finer detail, but as expected it also shows slightly higher noise levels as well as some chromatic aberration that the camera suppresses in its JPEGs. Bottom line: When coupled with a good converter, the Nikon Coolpix A rewards RAW shooters with great detail and sharpness.
ISO & Noise Performance
Great high ISO performance for a camera of this size.
|High ISO Noise Reduction = Normal (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 Nikon A's images are very clean at ISO 100 through 400, with just a touch of luminance noise becoming visible at ISO 800. 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, though chroma noise is more visible in the shadows. At ISO 3,200, luma noise is coarser and chroma noise more visible, but detail is still quite strong. ISO 6,400 is of course noisier, but still pretty good for such a high ISO. ISO 12,800 and ISO 25,600 in particular show a lot of chroma noise, in the form of yellow and purple blotches, as well as much stronger luminance noise. Saturation also drops slightly as ISO increases. Still, amazing high ISO performance for a camera its size.
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.
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. We know this; 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. :-) The focus target position will have been adjusted to insure that the rest of the scene is focused properly.
Extremes: Sunlit, dynamic range, and low light tests
Very good detail in both highlights and shadows. Very good low-light performance, capable of capturing bright images in near darkness.
|0 EV||+0.3 EV||+0.7 EV|
The Nikon Coolpix A handled the deliberately harsh lighting very well in the above test. Default contrast is a little high, however highlight and shadow detail are still very good. The +0.3 EV exposure did the best job here overall, as the mannequin's face was too dim at 0 EV (default exposure) and we thought a few too many highlights were lost at +0.7 EV. (+0.5 EV would have probably been ideal, as the eyes are still a bit dim at +0.3 EV.) Only a few highlights were blown in the mannequin's shirt and bright flowers at +0.3 EV, while very good detail was preserved in the shadows with lower than average noise. The camera's contrast adjustment also did a good job of decreasing overall contrast without also affecting color saturation. (See below.) Still, be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible.
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.)
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 Nikon Coolpix A JPEG file with a nominally-exposed density step target (Stouffer 4110). At the base ISO of 100 (the optimal ISO), with Active D-Lighting set to Off and default Contrast setting, the graph shows 10.9 f-stops of total dynamic range, with 9.61 f-stops at the "High" Quality level. The curve at highlight end rolls-off gradually, however the shadow end is a little disjointed and non-linear, which can lead to some posterization in very deep shadows. The Coolpix A's score at the highest quality level is however exceptional for an APS-C camera. For example, the well regarded Nikon D7000 scored 7.97 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 (.NEF) file, processed with Adobe Camera Raw using the Auto setting and tweaking from there. As can be seen, the score at the highest quality level increased almost a full stop from 9.61 to 10.6 f-stops, while total dynamic range increased substantially from 10.9 to 12.7 f-stops. Again, these results are remarkable, besting the D7000's 10.1 f-stops at the highest quality level. It's worth noting here is that ACR's default noise reduction settings reduced overall noise somewhat (see the plot in the lower left-hand corner) relative to the levels in the in-camera JPEG, which would tend to boost the dynamic range numbers for the higher quality thresholds.
We really like it when a camera gives us the ability to adjust contrast and saturation to our liking. It's even better when those adjustments cover a useful range, in steps small enough to allow for precise tweaks. Just as with its saturation adjustment, the Nikon Coolpix A's contrast setting offers seven levels, plus an Auto setting.
|Contrast set to lowest,
|Contrast set to lowest,
At its lowest contrast setting, the Coolpix A did a very good job of preserving highlight detail and bringing out shadow detail. Highlight retention was improved, but the contrast setting had a larger impact on opening up the shadows. The lower contrast setting opened-up shadows in our far-field shot as well, without making the image too flat looking. Overall, very good results here.
|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. 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.
Nikon's contrast adjustment is that it has very little effect on saturation. Contrast and saturation are actually fairly closely coupled, it's a good trick to be able to vary one with out the other changing as well. As usual, Nikon did a very good job here.
Active D-Lighting attempts to preserve detail in both highlights and shadows in high-contrast situations, while maintaining moderate levels of contrast. The series of shots below show the effect of the various Active D-Lighting settings available on the Nikon Coolpix A on our high-contrast "Sunlit" Portrait scene. Note that Active D-Lighting is different from the touch-up menu's D-Lighting, as it is performed during image capture instead of after. (It does affect only JPEG images though, Nikon very properly doesn't apply tonal adjustments like this to RAW file data. NEF files, however, are tagged so that Nikon software can automatically apply the effect when converted.)
"Sunlit" Portrait Active D-Lighting (+0.3 EV)
Mouse over the links to see how the various levels of Active D-Lighting affects our "Sunlit" Portrait shot at +0.3 EV exposure. Click on a link to get to the full-res image. (Active D-Lighting's 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.)
As you can see from the thumbnails and histograms, Active D-Lighting simultaneously boosts both shadows and midtones while reducing exposure of highlights, yielding better overall exposures compared to the Off setting, It's nice that Nikon provides control over the strength of this effect, making it easier to deal with high-contrast subjects in harsh lighting.
with matrix metering
+ Face-priority AF
|Full Auto mode
Here, we can see the effect of the Coolpix A's Face-priority AF and full Auto mode which selected Portrait Scene mode. As you can see, just enabling Face-priority AF made quite a difference, detecting and exposing for the face versus default Matrix metering mode in Aperture-priority. Full Auto mode did even better, selecting a larger aperture of f/4.5 for better subject isolation and applying some Active D-Lighting to reduce overall contrast. Excellent results here.
Low Light. The Nikon Coolpix A performed well on the low-light test, capturing usable images at the lowest light level (1/16 foot-candle) even at the lowest sensitivity setting (ISO 100). As you'd expect, noise increases as ISO goes up and light levels go down, but remains well controlled and fine-grained to ISOs as high as 3,200. We did not detect any significant issues with hot pixels. Some minor banding (pattern noise) could be seen at ISOs 12,800 and 25,600, as well as some heat blooming emanating from the bottom edge for longer exposures, but that's not unusual at such high ISOs.
Color balance was cool with the Auto white balance setting at the 1-foot candle level, though there's a strong shift towards magenta at lower light levels.
The Nikon Coolpix A was able to autofocus down to just below the 1/8 foot-candle level in our tests which is quite good for contrast-detect AF (thanks to its relatively fast f/2.8 lens), and in complete darkness with its AF assist lamp enabled. 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.) The Nikon Coolpix A uses contrast-detect autofocus, as is found in most point & shoot cameras, so its low-light focusing ability is less than that of some SLRs with phase-detect systems. That said, though, the larger, more sensitive pixels of the Coolpix A'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.)
Excellent 24 x 36 inch prints at ISO 100/200; very good 11 x 14 at ISO 3200 and a nice 5 x 7 at ISO 12,800.
ISO 400 also prints quite nicely at 24 x 36 inches.
ISO 800 images are very crisp at 16 x 20, which is a fairly large size for this ISO, retaining excellent color throughout.
ISO 1,600 makes a really good 13 x 19 inch print, with 16 x 20s here acceptable for less critical applications where a bit of film-esque noise is okay.
ISO 3,200 prints a nice 11 x 14, with only minor noise apparent in some shadowy areas.
ISO 6,400 shots look good at 8 x 10 inches. It is here that we should note just how good our target red swatch still looks, as it generally gives most cameras fits by this high an ISO.
ISO 12,800 produces a very nice 5 x 7 inch print for such a high ISO.
ISO 25,600 yields a usable 4 x 6 for some instances and is not terrible, but is not quite up to what we can deem as "good."
The Nikon Coolpix A does a wonderful job in the print quality department, and that's probably enough said. But if you are interested in just how good this fixed lens compact camera really is, it should be noted that it rivals its APS-C DSLR cousins across virtually the entire range in the sizes it is capable of, and it prints the same size at ISO 12,800 as the highly touted Sony RX1, which is more than twice the price. Add in the fact that the Coolpix A renders the trickiest part of our test target just about as well as any camera sold for under $3000 and you get a lot more of the picture.
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 Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)