Sony W70 Exposure & Imaging
The Sony DSC-W70 provides the usual point & shoot "green zone" fully automatic exposure mode, as well as a healthy handful of scene modes for special subjects, and a high-ISO mode for shooting under dim lighting. It also offers a programmed exposure mode that gives the user a modicum of control, including such things as focus, metering mode, exposure compensation, ISO setting, white balance, etc. It even offers adjustments for color saturation and image sharpness. All in all, the W70's exposure modes go well beyond the basic point & shoot necessities.
Print quality from the W70 is quite good, it's 7.2 megapixel CCD producing enough resolution to make 13x19 inch prints that are a little soft but more than adequate for wall display. The more common 8x10 inch enlargements are tack-sharp, even allowing for a fair amount of cropping. The Sony W70 does surprisingly well at high ISOs: Its ISO 400 images look fine when printed as large as 8x10 inches, and even its ISO 800 and 1,000 shots are usable at sizes of 5x7 inches and below.
All in all, the Sony W70 is a capable camera in a very compact case, with a good assortment of controls and options. Read on below for our specific test results.
Saturation & Hue Accuracy
Slightly oversaturated reds, blues, and yellows, though generally good overall color and hue accuracy.
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. The Sony Cyber-shot DSC-W70 does push strong reds and blue tones some, though results are generally pleasing. 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. Here, the W70 produced good looking skin tones, with just a slight warm tint that most consumers should find quite pleasing.
The other important part of color rendition is hue accuracy. Hue is "what color" the color is. Like most digicams, the W70 shifts cyan colors toward blue (a very common tactic, apparently aimed at producing better-looking sky colors) and blue-greens toward cyan. Overall color accuracy was very good though, actually among the best we've seen to date.
Exposure and White Balance
Indoors, incandescent lighting
A warm cast with both Auto and Incandescent white balance settings, average positive exposure compensation required.
|Auto White Balance +1.0 EV||Incandescent WB +1.0 EV|
Color balance indoors under incandescent lighting was quite warm and reddish in Auto white balance mode, and the Incandescent setting also resulted in a pronounced warm cast. The Sony DSC-W70 required a +1.0 EV exposure compensation adjustment, which is about average for this shot, though the highlights on Marti's shirt are quite hot at that setting. In addition to the strong warm cast, overall color is a bit dark here, making the blue flowers very dark and purplish. (A very common outcome for this shot.) Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulb, a pretty yellow light source, but a very common one in typical home settings here in the US.
Good overall exposure and color outdoors.
|Auto White Balance, Auto Exposure||Auto White Balance, Auto Exposure|
Outdoor shots generally showed nearly accurate exposure with slightly blown out highlights. Shadow areas held onto a good amount of detail, though with some noise suppression to lessen definition. Overall color looked good as well, if just a hint dark in some cases.
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, with extinction at around 1,800. 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. Beware that while you might be able to make out what looks like distinct lines at numbers higher than those we've mentioned here, the camera is just doing its best to continue interpreting the lines. If you zoom in and follow them from the wider portions, you'll see the lines converge and reappear several times, so the lines you see at 1,700 and higher are really only artifacts generated by the camera's imaging system.
|Strong detail to 1,200~1,300 lines horizontal||Strong detail to 1,200~1,300 lines vertical|
Sharpness & Detail
Sharp images overall, though some blurring of detail from noise suppression.
|Good definition of high-contrast elements.||Subtle detail: Hair
Noise suppression tends to blur detail in areas of subtle contrast, as in the midtone areas of Marti's hair here.
The Sony DSC-W70's images are sharp and clear overall, without any strong over-sharpening or edge enhancement on the camera's part. (Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.)
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. The crop of Marti's hair above shows this in the darker shadows, though quite a few individual strands of hair are visible in the brighter shadows and highlights.
ISO & Noise Performance
Moderate noise at the normal sensitivity settings with slightly blurred detail, but very high noise with stronger blurring at the higher settings.
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1,000|
The Sony DSC-W70's lower ISO settings produced moderate noise, with only slightly blurred detail in the dark areas. As you'd expect, noise level increased significantly with the higher ISO settings, resulting in a stronger noise pattern and stronger blurring. That said, most consumers would probably consider ISO 400 shots usable at print sizes as large as 8x10 inches. Shots at ISO 800 and 1,000 are noisy and a little soft even at 5x7 inches, but just fine for 4x6 prints.
Extremes: Sunlit and low light tests
High resolution and strong detail overall, though slightly limited shadow detail. Pretty good low-light performance, capable of capturing bright images under average city street lighting and slightly darker conditions.
|+0.7 EV||+1.0 EV||+1.3 EV|
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.)
The Sony Cyber-shot DSC-W70 performed fairly well in response to the deliberately harsh lighting in the test above, though contrast is slightly high and shadow detail a bit limited. Noise suppression in the shadows also contributes to the loss of detail. Although Marti's skin tones and some of the foliage of the flower bouquet is a little dark there, the best exposure was obtained at +1.0 EV, which is about average for this shot. Though midtones are brighter at +1.3 EV, highlights are just too hot. (In "real life" though, be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible.)
Our low light testing revealed some limitations in the DSC-W70's lens and sensor abilities, though the camera is capable of capturing bright images under average city street lighting at night (about one foot-candle). At the higher ISO settings, images were bright down to about 1/4 foot-candle, which is about a quarter the brightness of average city street lighting. The camera's autofocus system was able to focus on the subject down to the 1/4 foot-candle light level unassisted, and down to the darkest light level we test at with the AF assist lamp enabled. Keep in mind though, that the longer shutter times here demand the use of a tripod or other camera support to get sharp photos. (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.)
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 somewhat limited range for the W70's flash, particularly at telephoto focal lengths. Our standard shots required a High Intensity boost for good results.
|38mm equivalent||114mm equivalent|
|Normal Flash, High Intensity||Slow-Sync Flash, High Intensity|
Flash coverage was rather uneven at wide angle, and just slightly uneven at telephoto. In the Indoor test, the DSC-W70's flash underexposed our subject at its default setting, and required a High Intensity boost for bright results. Even here, the exposure is a little dim, with a slight pink cast. (This shot commonly requires +1.0 - 1.3 EV of exposure boost, so the W70's results are actually pretty typical.) The camera's Slow-Sync flash mode produced slightly brighter and more even results, though with a strong orange cast from the room lighting. Despite the longer shutter time, the Slow-Sync mode also required a High Intensity boost.
At wide angle, shots at ISO 100 are bright out to a distance of about 9 feet, decreasing in brightness from that point on. At full telephoto and ISO 100, even the 6-foot shot is a little dim, and the images darken from there. Bottom line, an unimpressive flash range, at least at ISO 100.
|Manufacturer-Specified Flash Range|
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. In the shots above, the Sony W70 exposed properly at the officially rated distances, but only by boosting the ISO a fair bit, which increases image noise.
Good print quality, great color, soft but usable 13x19 inch prints. ISO 400 images are a bit soft and noisy but quite usable at 8x10 inches. ISO 800 and 1000 shots are best limited to 5x7 inch or smaller prints.
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.)
The Sony W70 delivers enough resolution to make 13x19 inch prints that are slightly soft, but more than acceptable for wall display. At high ISOs, its images are somewhat noisy, but 8x10 inch prints from ISO 400 shots should be acceptable to most consumers. At ISO 800 and 1000, noise increases further, despite the anti-noise processing's impact on image sharpness. Still, while the ISO 1000 images are pretty noisy, we think most consumers would be perfectly happy with prints as large as 5x7 inches made from them.
Color-wise, images from the Sony W70 printed on our Canon i9900 printer were quite appealing. Colors were bright and vibrant without looking overdone. Greens were a little muted relative to images from some other cameras we've tested, but this was only apparent when comparing prints from competing models side by side. Viewed on their own, prints from the W70 looked very good. (The W70's handling of greens is actually accurate, neither over- nor under-saturated. The reason its green hues look a little dull relative to other cameras is because most consumer cameras oversaturate greens somewhat to produce artificially bright, vibrant foliage colors.)