Nikon D7100 Exposure
Nikon D7100 Image Quality
Saturation & Hue Accuracy
Realistic saturation levels and good 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 on them for larger images.|
Saturation. The Nikon D7100 pushes dark greens and blues by a moderate amount, but slightly undersaturates bright yellow, light green, and some cyans. Reds are also pushed a bit, but not as much as by most cameras. Overall saturation levels are good and remain fairly stable, climbing slightly as ISO increases. Mean saturation is 106% at base ISO, or 6% oversaturated. The average for consumer DSLRs is about 10% oversaturated, but 6% is closer to accurate, and it's easy to customize saturation to match your personal preference. 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 Nikon D7100's Caucasian skin tones looked just about right when using Auto white balance in simulated daylight, while Manual white balance produced an overly pinkish cast. A very good job with Auto white balance. 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 D7100 did shift cyan toward blue, red toward orange, and light green toward yellow, but shifts were 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 4.68 after correction for saturation, overall hue accuracy was a bit better than average. Hue is "what color" the
The Nikon D7100 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 D7100OUTBSATx.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 and 2,600 Kelvin white balance settings, but overly-warm results with Auto and Incandescent. Negative exposure compensation required.
|Auto White Balance
|Incandescent White Balance
|Manual White Balance
Indoors, under normal incandescent lighting, color balance was very warm and reddish with the Auto white balance setting. (We'd say unacceptably so, though unfortunately this is common.) The Incandescent setting was also too warm, this time with a yellowish cast. The Manual setting produced the most accurate results, if just a touch cool, and the 2,600 Kelvin setting which should match our lets wasn't far off. The Nikon D7100 required negative exposure compensation here (-0.3 EV) while the average compensation needed for this shot is +0.3 EV. Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.
Excellent results under harsh lighting, with very good handling of color and contrast, but the D7100 tends to overexpose a bit.
|Auto White Balance,
|Auto White Balance,
Outdoors, the Nikon D7100 performed well in terms of color and contrast, but it tended to overexpose a bit. The D7100 required only +0.3 EV of exposure compensation to keep the mannequin's face bright, while most cameras need about +0.7 EV. The camera did a very good job of holding onto detail in the highlights and deep shadows. We preferred skintones from the Auto white balance setting as they weren't overly pink as with Manual white balance. The Nikon D7100 slightly overexposed our far-field scene producing an image that was a bit too bright overall, but it still managed to avoid blowing most highlights. Color outdoors was generally quite pleasing.
Very high resolution, ~2,600 to ~2,700 lines of strong detail from JPEGs, ~2,800 from ACR processed RAW files.
|Strong detail to
~2,600 lines horizontal
|Strong detail to
~2,700 lines vertical
|Strong detail to
~2,800 lines horizontal
ACR processed RAW
|Strong detail to
~2,800 lines vertical
ACR processed RAW
Our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,600 lines per picture height in the horizontal direction and about 2,700 in the vertical direction. Extinction of the pattern didn't occur until around 3,600 lines in both directions. We were impressed that the D7100 did a pretty good job at suppressing color moire, as we expected to see much more from a camera without an anti-alias (optical low pass) filter.
We were able to do a bit better with NEF files processed through Adobe Camera Raw, with the horizontal and vertiical directions showing about 2,800 lines before aliasing artifacts started interfering with the pattern, while complete extinction of the pattern was extended up to the 4,000 line limit of our chart. As usual, color moire was more evident in the converted RAW files. 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 but with excellent detail. Very minor edge-enhancement artifacts visible on high-contrast subjects. Moderate noise suppression visible at base ISO.
Sharpness. The Nikon D7100 produced very sharp, detailed images overall when coupled with a sharp lens such as the Nikon 35mm f/1.8G prime used in the above left crop Some very minor edge enhancement artifacts are visible on high-contrast subjects such as the halos around the branches in the crop above left, but overall sharpness is excellent, thanks to the lack of an AA filter. 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 some mild to moderate noise suppression, as the darker and lower-contrast areas of the model's hair show significant smudging where individual strands of hair merge. Still, a pretty good performance here for a 24-megapixel APS-C sensor. 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 D7100 delivers very detailed JPEGs that are quite sharp when taken with a sharp lens. Even better detail 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, and a 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 250% unsharp mask and a radius of 0.3 pixels worked well for the Nikon D7100'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, and the software wasn't really able to extract more detail. Adobe Camera Raw was able to extract quite a bit more fine detail in the pine needles, but as expected, it also shows slightly higher noise levels as well as some moderate chromatic aberration (we did not attempt to correct it) that the camera suppresses in its JPEGs. Bottom line: When coupled with a sharp lens and good raw converter, the Nikon D7100 rewards raw shooters with astounding detail.
ISO & Noise Performance
Excellent detail versus noise handling up to ISO 1,600.
|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|
Noise levels are fairly low at ISOs 100 through 800, though some detail is lost to noise reduction and an increase in very fine noise "grain" can be seen as ISO increases. Some minor chroma noise is also visible in the darker shadows, even at base ISO, though it's not objectionable. At ISO 1,600 noise levels increase with a touch more blurring in the fine details and more visible grain, but detail is still quite good. ISOs 3,200 and 6,400 show larger steps in both luma and chroma noise and shadows begin to show noticeable color blotching. At ISO 12,800, luma noise is quite high and shadows take on a yellow tint. At the highest ISO, noise is very high with strong yellow and purple blotching in shadows and midtones.
Still, very good noise performance considering the 24-megapixel resolution, but it's no surprise that noise is higher at the pixel level than its 16-megapixel siblings. See our Print Quality analysis section below for recommended print sizes at each ISO.
A note about focus for this shot: We shoot this image at f/4, usually 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. 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 high resolution and good overall exposure. Very good low-light performance, capable of capturing bright images in near darkness.
|Default||+0.3 EV||+0.7 EV|
The Nikon D7100 handled the deliberately harsh lighting in the test above very well. Though contrast is a little high, shadow and highlight detail are both very good. The +0.3 EV exposure was best here, producing a bright face without blowing out many highlights. Despite the bright appearance, there are actually very few clipped highlights in the mannequins's white shirt. Some shadows are pretty dark, but remained fairly clean. 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 D7100 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 12.4 f-stops of total dynamic range, with 8.41 f-stops at the "High" Quality level. These are very good results for an APS-C model, especially a high-resolution model like the 24-megapixel D7100, with its smaller photosites. In comparison, the 16-megapixel D7000 scored 7.97 at the highest quality level. 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 1.69 f-stops from 8.41 to 10.1 f-stops, while total dynamic range increased 0.7 f-stops to 13.1. Again, these results are remarkable, matching the D7000's 10.1 f-stops at the highest quality level, despite the smaller photosites. 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 D7100's contrast setting offers seven levels, plus an Auto setting.
|Contrast set to lowest,
|Contrast set to lowest,
At its lowest contrast setting, the D7100 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, though the yellow push we've seen in the shadows of these shot is more apparent. 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 D7100 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 default 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.)
When Active D-Lighting is enabled, the camera usually for the highlights in an attempt to preserve them, then adjusts the tone curve to bring the midtones and shadows back up to produce an image that doesn't look underexposed. Here, we can see Active D-Lighting performed as expected, with higher settings toning down more highlights, while all settings boost shadows.
See below for how Active D-Lighting worked on our Far-field shot.
|Far-field Active D-Lighting (0 EV)|
Here are the results with our Far-field shot. The D7100's Active D-Lighting worked well here, too. As you can see, Active D-Lighting brought up shadow detail while holding on to more of the highlights. The Auto setting did a pretty good job here.
The D7100 is only the third Nikon DSLR offering an in-camera high-dynamic-range imaging function (the D5100 and D5200 were the first), something we've seen in a number of DSLRs from competing manufacturers. When enabled, the D7100 captures two images with one push of the shutter button, one underexposed and one overexposed and combines them in-camera to produce a high-dynamic-range JPEG. (RAW format is not supported). We don't believe the Nikon D7100 performs any micro-alignment of the two images even though the user manual warns of possible cropping. If it is, it can only correct for very small amounts of camera movement between shots, and so Nikon recommends the use of a tripod. Obviously moving subjects should also be avoided.
"Sunlit" Portrait HDR (+0.3 EV)
Unlike the Nikon D5100 which allowed you to set the exposure differential between the two images from 1, 2 or 3 EV, and also adjust the amount of "smoothing" that is applied to the boundaries between the two images with selections of Low, Medium and High, the D7100 takes a simpler approach offering just four strengths in addition to Auto. Mouse over the links above to see how various levels of HDR affects our "Sunlit" Portrait shot and click on a link to get to the full-res image. Again, because of the underexposure issue, these aren't very good examples, but you can still see higher levels make quite a difference to the overall exposure by opening up shadow detail but they can lead to artificial looking shadows around bright objects or halos and glowing around dark ones. Colors can also be adversely affected in HDR mode, such as a drop in saturation. Still, it's a useful feature for capturing static scenes with dynamic range that exceeds the sensor for those not willing to use manual HDR techniques (bracketing exposure and then combining images while post-processing).
|Far-field HDR (0 EV)|
Here are the same HDR settings with our Far-field shot. Again, some settings do a good job of taming hot highlights while bringing up some of the shadows and deeper midtones. You can also see ghosting in the tree branches and leaves from movement between the exposures caused by wind, as well the uneven and artificial-looking exposure when using higher settings.
with Face-priority AF
Here, we can see the effect of the Nikon D7100's full Auto mode which selected Portrait Scene mode, as well as face detection enabled in Live View mode. As you can see from the shots above, the Portrait Scene mode made an improvement to exposure versus Aperture-priority at f/8 at 1/60s, reducing overall contrast and lightening shadows, though noise is a bit higher as it boosted ISO sensitivity to 400. Portrait mode also selected a wider aperture of f/5.6 for better subject isolation, and a faster shutter speed of 1/500s to avoid subject motion blur. In Live View using Aperture-priority, Face-priority AF mode made only a small difference by using a slightly slower shutter speed of 1/50s.
Low Light. The Nikon D7100 performed well on the low-light test, capturing usable images at the lowest light level (1/16 foot-candle) with 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 other than a few of them when long exposure NR is turned off, but that's to be expected. Some minor banding could be seen at higher ISOs and lower light levels (particularly with long exposure noise reduction turned off), as well as some heat blooming emanating from the bottom edge for longer exposures, but that's not unusual.
Color balance was good with the Auto white balance setting, just slightly cool, though there's a strong shift towards magenta at lower light levels, particularly at lower ISOs.
The camera's phase-detection autofocus system was able to focus on the subject down to below the 1/16 foot-candle light level unassisted with an f/2.8 lens, which is quite good. The Nikon D7100 was however able to autofocus in complete darkness with the AF assist enabled. In Live View mode the camera's contrast-detect autofocus struggled a bit, as it was only able to focus down to just above 1/2 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.) Digital SLRs like the Nikon D7100 do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
Very nice 36 x 48 inch prints at ISO 100/200; makes a good 20 x 30 inch print at ISO 800 and a usable 5 x 7 at ISO 12,800.
ISO 100/200 images are excellent with very fine details and bright, accurate colors up to 36 x 48 inches. Size down to 30 x 40 inches, and the prints look outstanding, while all the way up to 40 x 60 inches, and prints are quite suitable for wall display.
ISO 400 allow for great prints up to 24 x 36 inches, while 30 x 40 inch prints are suitable for wall display.
ISO 800 images look good at 20 x 30 inches. There is some noise, but you only really notice it in the shadow areas, and even then, the grain is reminiscent of film grain and not present over the entire image. 24 x 36 inch prints are suitable for wall display.
ISO 1600 makes a good 13 x 19 inch print with plenty of fine detail. At 16 x 20, the image is a little too soft in finely detailed areas. Noise becomes quite noticeable in the shadows (although still appearing more like film grain), but noise in the highlights and midrange areas are very low. If the image was of a brightly-lit scene or exposed to the right, noise would be virtually unnoticeable.
ISO 3200 prints start to show a fair amount of noise, but it still produces a nice 11 x 14 inch print. As before, shadow noise is apparent, but otherwise the image looks great and fine details are still noticeable.
ISO 6400 makes a decent 8 x 10, but noise and a reduction in fine detail is taking its toll on the image quality, preventing us from calling anything larger acceptable. We were amazed by how well the D7100 handles the red fabric in our test shot even at this high ISO.
ISO 12,800 images are fairly heavy on noise at larger sizes, but can still produce a decent 5 x 7 inch print. Colors still look good, but fine detail, such as in the red fabric and mosaic area, is almost nonexistent.
ISO 25,600 images were difficult to call as there was quite a bit of noise and low detail, but colors were still acceptable in 4 x 6 inch prints. While we can't call a 4 x 6 acceptable at this ISO, it would certain do in a pinch for less critical applications.
The Nikon D7100's 24.1-megapixel APS-C sensor that also lacks an optical low-pass filter produces excellent results for very large prints at low ISO levels, all the way up to wall-mountable 40 x 60 inch prints at ISO 100 and 200. Additionally, this camera is capable of images that retain wonderful colors and fine details even as the ISO increases. Like its sibling camera the D5200, this was a difficult camera to grade because its results in some areas exceeded expectations. At the higher ISO levels between 1600 and 12,800, we were on the fence many times for which way to go in calling an acceptable size. Even at ISO 25,600, it was difficult to call. The D7100 retained a great amount of fine detail at high ISOs, but we saw noticeable noise grain in the shadow areas at higher ISOs. Even still, the noise on these high ISO prints reminded us of film grain and users might like the way noise looks on higher ISO prints for certain instances. Overall, the D7100, Nikon's latest entry into the "DSLRs without optical low-pass filters" category, produces stellar low-ISO prints at very large sizes with incredible levels of detail for an APS-C sensor, yet it still does a fantastic job with prints at higher ISO levels.
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.)
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Nikon D7100 Photo Gallery .
Not sure which camera to buy? Let your eyes be the ultimate judge! Visit our Comparometer(tm) to compare images from the Nikon D7100 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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