Nikon L15 Exposure

Saturation & Hue Accuracy
Good overall color and hue accuracy, with some undersaturation in blues and violets.

Saturation. The Nikon Coolpix L15 oversaturates strong reds a small amount, but keeps other tough colors like strong blues and yellows about right. Some blues and purples are actually a little undersaturated. Still, overall results were pleasing across a range of subjects. 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 Coolpix L15 did produce slightly pinkish skin tones in some cases, and slightly cool skin tones in others. Overall though, results were within acceptable limits. 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 Coolpix L15 showed only a few small color shifts relative to the correct mathematical translation of colors in its subjects, nudging cyan slightly toward blue and orange toward yellow. Despite these slight shifts, color was quite accurate. Hue is "what color" the color is.

Exposure and White Balance

Indoors, incandescent lighting
Good color with Manual white balance, though slight casts with the Auto and Incandescent settings. Less than average positive exposure compensation required.

Color balance indoors under incandescent lighting was quite warm in Auto white balance mode, and the Incandescent setting produced a slightly warm cast as well. Manual mode was the most accurate overall. The Nikon L15 required only a +0.7 EV exposure compensation boost, which is just a little lower than average for this shot. Overall color with the Manual white balance setting is quite good, though the blue flowers are dark and purplish. (Many digital cameras reproduce these flowers with a dark, purplish tint, so the Coolpix L15 struggled a bit here.) 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
Good overall color and exposure, though slightly high contrast and hot highlights.

Outdoors, the Nikon Coolpix L15 did produce slightly high contrast images under harsh lighting, as you might expect, but our Outdoor Portrait actually required slightly less positive exposure compensation than normal. Highlights are a bit bright on the white shirt and on Marti's face, but the camera manages to hold onto detail. Where things fall apart is the shadow areas, where strong noise and noise suppression really blur the details. Overall color is pretty good, with the reds just bright enough to keep from dominating the image, and good saturation elsewhere.

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Resolution
Moderately high resolution, 1,300 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,300 lines per picture height in both directions. You could argue for 1,400 lines, but the lines are starting to blur a little here. Extinction occurred around 1,800-1,900 lines. 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.

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Sharpness & Detail
Edge-enhancement artifacts on high-contrast subjects, as well as high noise suppression.

Sharpness. The Nikon Coolpix L15 captures fairly sharp images overall, though fine detail definition is a bit soft. Some edge enhancement artifacts are visible on high-contrast subjects such as the crop above left, and a small amount of noise as well. 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 strong noise suppression, with darker areas of Marti's hair showing limited detail. Individual strands are lost amid noise pixels and smudgy definition. This shot was taken at ISO 400, however, so more than a little softness is expected; however, this is more than is acceptable among modern 8-megapixel digital cameras at ISO 400. 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.

ISO & Noise Performance
Strong noise and blurred details at higher ISOs, camera maintains control over ISO setting.

Noise levels and efforts to suppress noise are quite evident at the Coolpix L15's 400 ISO setting. In the crop above, noise pixels are quite noticeable, as well as efforts by the camera to suppress noise. The end result is smudgy detail. Because the camera keeps ISO under automatic control, you won't have much control over the resulting image noise. Thus, when shooting in low lighting, expect higher noise and noise suppression efforts than when shooting under brighter conditions.

Extremes: Sunlit and low light tests
High resolution with strong overall detail, but slightly high contrast and limited shadow detail. Fair low-light performance, capable of capturing bright images in near darkness, though the camera greatly raises ISO to do so.

Sunlight. The Nikon Coolpix L15 produced high contrast with strong highlights under the deliberately harsh lighting in the test above. Though highlights are bright, detail is good in the white shirt. Shadow detail suffers from noise suppression, showing limited, blurry detail. The camera required about average compensation to get proper exposure of skin tones, at +0.7 EV. In real life, be sure to use fill flash in situations like the one shown above; and 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.)

Low light. The Nikon Coolpix L15 struggled a bit with our low-light test. While it was able to capture bright images at almost the lowest light level, the camera raised the ISO to 1,000 to get good results here. Even at the brightest setting, one foot-candle, the camera required ISO 800 to get a bright image. Thus, both noise and noise suppression are high, resulting in blurred details. The camera's autofocus system was only able to focus just below the one foot-candle light level unassisted, though with AF assist it focused down to the darkest light level. Keep in mind that the longer shutter times here demand the use of a tripod for the best results. (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.) For such applications, you may have better luck with a digital SLR camera, but even there, you'll likely need to set the focus manually. For information and reviews on digital SLRs, refer to our SLR review index page.

Coverage and Range
A slightly dim flash at close range, with uneven coverage up close. However, our standard shots required slightly lower than average exposure compensation.

Coverage. Flash coverage was uneven and dim at wide angle, but much more uniform at telephoto. In the Indoor test, the Coolpix L15's flash underexposed our subject just a little at its default setting, requiring a +0.7 EV exposure compensation adjustment to get good results. The camera's Slow-Sync flash mode produced brighter and more even results at its default exposure, though with a stronger pinkish-orange cast from the room lighting.

Auto ISO Range. At wide angle, flash shots at the Auto ISO setting remained fairly bright out to a distance of about 16 feet, though the camera increased the ISO to 400 to compensate. At full telephoto and Auto ISO, the target at 6 feet was actually a little dim, but results at 16 feet were bright. (Normally this is the ISO 100 Range test, but the Nikon L15 offers only Auto ISO mode.)

Manufacturer Specified Flash Test. In the wide angle shot above, the Coolpix L15 performs nearly as Nikon says it will, overexposing at the rated distance with its ISO set to Auto. Auto ISO selected ISO 800, resulting in a heavily noise-processed image (blurry). At telephoto, the image is just slightly dim, despite an ISO boost to 400.

Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We've now also begun shooting two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of the specific claims.

Print Quality
Fair print quality, subdued color, sharp 8x10-inch prints. ISO 400 images are soft at all but 4x6 inches.

The Nikon Coolpix L15 had only enough resolution to make good looking 8x10 inch prints at ISO 64, much smaller than most 7.1-megapixel sensors can produce, let alone the L15's 8-megapixel counterparts. ISO 400 shots are soft at 5x7, slightly better at 4x6, though the color is muted. Since the L15 automatically raises the ISO indoors, only close-range flash shots are usable when indoors. If the camera keeps ISO to 64 or 100, these are usable up to 8x10. Otherwise, indoor images are only just usable when printed at 4x6 inches.

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 i9900 studio printer, and on the Canon iP5200 here in the office. (See the Canon i9900 review for details on that model.)