Panasonic DMC-ZS7 Exposure

Saturation & Hue Accuracy
Very good overall color and hue accuracy, with only minor oversaturation of some colors.

Saturation. The Panasonic ZS7 produced very good saturation overall, with only minor oversaturation in blues, purples and some greens. as well as some greens, some reds and purples. Some other colors such as cyan, yellow and some greens were undersaturated a small amount. Overall, the Panasonic ZS7's images appeared to have natural looking color that didn't appear dull. See the Print Quality section below, though, for more on a problem with yellows that look more orange or green. 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. Here, the Panasonic ZS7's skin tones looked a little flat, with only slight warmth. The camera's Portrait mode adds a nice healthy glow, though. 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 Panasonic Lumix ZS7 produced a few color shifts relative to the correct mathematical translation of colors in its subjects, most visibly pushing cyan towards blue (for better-looking skies), red toward orange, and yellow toward green. Still, most shifts were minor and overall hue accuracy was very good. Hue is "what color" the color is.

Exposure and White Balance

Indoors, incandescent lighting
Very good color with the Manual white balance setting. About average positive exposure compensation required.

Color balance indoors under incandescent lighting had a slight magenta cast to it with the Auto white balance setting, though it wasn't too far off the mark. Results were quite warm with the Incandescent setting. The Manual option was the most accurate; perhaps just a touch cool. The Panasonic ZS7's exposure system handled this lighting well, producing good results with an average amount of exposure compensation, +0.3 EV. Overall color looks pretty good, though the blue flowers look a touch purplish. (Many digital cameras reproduce the blue flowers here with more of a purplish tint, so the Panasonic ZS7 actually performs a bit better than average 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
Slightly high contrast, but generally good exposure and color.

Outdoors, the Panasonic Lumix DMC-ZS7 produced good overall color and exposure, though with slightly high contrast and bright highlights. Shadow detail was pretty good, though noise and noise suppression did limit detail definition there. In the portrait above, an average amount of EV boost (+0.7 EV) was necessary for good skin tones, but it wound up blowing quite a few highlights on the white shirt. Skin tones were somewhat flat, but Portrait mode (see below) added some warmth. Default exposure was a bit hot in the far-field house shot, resulting in some clipped highlights in the white trim. Color looked very natural.

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Resolution
High resolution, 1,700 ~ 1,800 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,800 lines per picture height in the horizontal direction, and about 1,700 lines in the vertical direction. (Some might argue for over 1,800 lines, but artifacts begin to appear at much lower resolutions.) Extinction of the pattern occurred between 2,200 and 2,400 lines in both directions. 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
Slightly soft images overall, but with only minor edge-enhancement artifacts on high-contrast subjects. Some noise suppression limits detail even at low ISOs in darker areas, even though some noise is still visible. That said, fine detail is better preserved than with many of its competitors.

Sharpness. The Panasonic ZS7 captures a lot of fine detail, though detail definition suffers somewhat from noise suppression, even at low ISO settings. Or it could be a side-effect of Intelligent Resolution. Still, the ZS7 preserves fine detail better than many of its competitors: A better-than-average performance in this area. Only slight enhancement artifacts are visible on high-contrast subjects such as 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 moderately high noise suppression, with the darker and low contrast areas of hair showing limited detail. Individual strands become smudged together and lose definition in the shadows. 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
Moderate but fine-grained noise at low ISOs, but noise and noise suppression quickly becomes fairly strong at the higher settings.

For its class, the Panasonic Lumix ZS7 shows very good detail at the lowest ISO sensitivity of 80. Luminance noise is visible, but it's quite fine grained leaving lots of detail except in shadows. Some minor chroma noise is also visible, but it's quite low. ISO 100 is only slightly noisier, with similar levels of detail. We start to see some smudging of fine detail due to stronger noise reduction at ISO 200. The chroma noise is all but gone at ISO 200 however. ISO 400 has even more detail blurred away, but an increase in sharpening to try to make up for the stronger blurring makes noise pixels and NR artifacts more visible. As you'd expect, the loss of detail continues at ISO 800, and chroma noise becomes an issue, with large patches of purple and yellow in shadows and midtones. ISO 1,600 is very soft due to heavy NR blurring, with visible noise pixel artifacts. On-screen crops like this tell you only part of the story with a camera, though: To see how these images held up when printing at various sizes, read the Output Quality section below.

Extremes: Sunlit and low light tests
High resolution with good overall detail, but somewhat high contrast. Good low-light capabilities.

Sunlight. The Panasonic Lumix ZS7 produced somewhat high contrast under the deliberately harsh lighting in the test above, with washed-out highlights and deep shadows. Noise and noise suppression artifacts limit detail in the shadow areas, though some detail there still remains. At +0.7 EV, the highlights on the white shirt are really quite hot, but the exposure at +0.3 EV was a little too dim in the face. The DMC-ZS7 does have an Intelligent Exposure mode, which attempts to correct for situations like this, by adjusting exposure and contrast automatically.

Intelligent Exposure. Here is the same series, but with Intelligent Exposure enabled. As you can see, the effect can be quite subtle. It seemed to work best with +0.3 EV compensation in this case, but would probably work better with a strongly backlit scene.

Face Detection. The above images show the effect of the Panasonic ZS7's face detection auto exposure in Portrait mode. The ZS7 Portrait mode did make a big difference to our Portrait shot, not only automatically adjusting exposure to keep the face bright, but also warming the skin tones and turning down the sharpening to reduce the visibility of blemishes. As you can see, auto exposure in Portrait mode was similar to our manual selection of +0.7 EV with Portrait mode off.

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 Panasonic Lumix ZS7 performed fairly well on the low-light tests. In Shutter Priority mode, the maximum exposure is 8 seconds. This increases to 60 seconds in Manual exposure mode, which is better than most compacts. The LZ7 would have no problem properly exposing at the lowest light level we normally test at. Noise is well controlled up to ISO 200, but higher ISOs should still be usable for smaller prints. Auto white balance performed well, resulting in fairly neutral color that was just a touch cool.

In the Special Modes examples above, Intelligent Exposure mode selected ISO 400, which is a bit noisy, but you may get away hand holding the camera with the help of the ZS7's optical image stabilization. Night Scene mode selected ISO 80, which is much cleaner, but the shutter speed is also much longer, requiring a tripod. (A useful trick when shooting under dim lighting 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.)

The camera's AF system preformed fairly well, able to focus down to about the 1/8 foot-candle light level unassisted, an in complete darkness with the AF 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.) 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
Fairly weak flash with uneven coverage at wide-angle. iAuto flash produced bright results.

Coverage. Flash coverage was uneven at wide-angle (but not too bad, given the wider-than-average 25mm equivalent focal length). Coverage is more uniform at telephoto, but even at ISO 1,000 the flash range isn't powerful enough for full telephoto in our test.

Exposure. In the Indoor test, the camera's iAuto mode produced a bright image, but boosted ISO sensitivity to 320 to compensate for the under-powered flash.

ISO 100 Range. At wide-angle and ISO 100, flash shots started out a bit dim at 6 feet, becoming gradually dimmer from there. At telephoto, flash shots were quite dim already at 6 feet, becoming dark at farther distances.

Manufacturer Specified Flash Test. In both the wide-angle and telephoto shots above, the Lumix ZS7's flash does not appear to perform to Panasonic's rated distances, producing somewhat dim exposures despite boosting ISO to 400 and 640 respectively. 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
Good print quality at 16x20 inches. ISO 400 images are soft but usable at 13x19, ISO 800 shots are better at 8x10, and ISO 1,600 shots are usable at 5x7 or smaller.

Prints from the Panasonic ZS7 are good up to 16x20 inches in terms of resolution at ISO 80 and 100, but there's a noticeable dark tint that affects certain colors in the test image, including yellow and orange colors. Detail is quite good, though.

ISO 200 shots make a good 13x19-inch print with only minor softening appearing in fine detail from noise suppression.

ISO 400 shots are usable at 13x19, but look better at 11x14.

ISO 800 shots are good at 8x10 with only minor luminance noise in the shadows.

ISO 1,600 shots are soft on close inspection, but look good when printed at 5x7 inches and smaller.

Overall a good performance from the Panasonic ZS7, though the rendering of yellows in particular is the only disappointing aspect.

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.)