Canon PowerShot S70

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http://reviews.cnet.co.uk/digitalcameras/0,39030233,39186590,00.htm

Reviewed 10 December 2004

Reviewed by Lori Grunin and Robert Dubbin

Though it fails to garner the same across-the-board high marks as its predecessors, the Canon PowerShot S70 nevertheless acquits itself very well as an enthusiast's compact. A 7-megapixel camera with a 3.6x zoom lens, the S70's first-rate photos and flexible feature set appeal now as much as they ever did. Only poor battery life and average performance hold it back from attaining better grades.

Design
The Canon PowerShot S70 has a pleasant heft to it, weighing 289g with its battery and media inserted. That's enough to rest comfortably in your hands without shaking too much while you're shooting, but after hanging off your arm via the wrist strap for more than a few minutes, it starts to feel heavy. The S70's black, metal body seems uniformly sturdy; a lone exception is the sliding panel that covers the battery and media compartment, which feels as if it could snap off with one clumsy move.

The camera's body is half-again as long as one of Canon's diminutive Digital IXUS ultracompacts, measuring 114mm across. In practice, the S70 is short enough to feel compact and fit in most pants pockets but also long enough to make two-handed shooting a comfortable endeavour. Those used to ultraslim or very compact point-and-shoots will likely find the S70 a bit clunky, and one-handed shooting is all but impossible without a tripod. The 46mm (1.8-inch) LCD screen stays bright and fairly readable even in direct sunlight, but it's a bit small compared to the 51mm (2-inch) displays that are becoming more popular in this market segment. Plus, as with most compact cameras, the S70's optical viewfinder is a diminutive and distorted alternative.

Canon logically lays out the buttons and controls on the PowerShot S70's rear. The menu button, the zoom control, the review toggle, the mode dial, and the four-way selector all lay within the arc of your right thumb, and the flash selector and the function/focus buttons are all easily reached by your left thumb. That's a lot of controls, but Canon intelligently allocates the division of labour between both thumbs; the left can bring up manual focus while the right clicks into shutter-priority mode, and tweaks both the focus and the shutter speed. Unfortunately, red-eye and flash-sync settings are buried in the main menu; they should be accessible from the flash button on the back of the camera.

The PowerShot S70's 3.6x optical-zoom lens protrudes from the front of the camera by a bit more than 25mm, regardless of whether you're at a wide-angle or a telephoto setting. As a result, you can seek out a comfortable grip without the danger of accidentally getting a finger in front of the lens. The same can't be said of the flash, so if you're lining up a shot where lighting is of particular importance, you'll want to be careful, as the hand position that feels most natural on the camera brings the edge of your finger close to the corner of the flash.

Features
With the exception of a couple of minor points, the Canon PowerShot S70 has a powerful set of features for enthusiasts. Its f/2.8-to-f/5.3, 28-100mm (35mm equivalent) lens delivers one of the wider viewing angles available in a snapshot camera and can focus to as close as 36mm. But the lens has a skimpy, 3.6x optical-zoom range stepped to eight positions. As for exposure modes, the S70 supplies all the essentials: full auto and program, shutter and aperture priority, and manual, as well as five scene presets. Centre-weighted average, evaluative, and two spot-metering modes give advanced users some exposure flexibility as well. You can set light sensitivity between ISO 50 and 400. As with most cameras in its class, you can also tweak exposure and flash exposure to ±2EV in 1/3-stop increments. The S70's flash extends a reasonable distance, about 4.3m at ISO 100.

The S70 also offers flexible focus options. You can manually select a focus area from anywhere within the centre two-thirds of the scene, fix it at the centre, or let the camera automatically select it for you with its nine-point AiAF system. Additionally, you can effectively combine them with the camera's Focus Bracketing feature. White-balance options consist of seven presets -- including Underwater (for when the camera's submerged in its optional underwater housing), auto, and manual.

In addition to support for raw files, you can mix and match five resolution settings with three JPEG compression levels. Canon also includes software that allows you to shoot with the camera tethered to a PC.

But if you want to shoot movie clips, look elsewhere. The S70 is limited to 30 seconds of 10fps, VGA-resolution capture with mono sound, which is disappointing in a camera of its class and price range.

Performance
The Canon PowerShot S70 delivers good but not great performance for its class. From power-on to first shot takes about 3.1 seconds. Shutter lag runs from 0.8 second under ideal conditions to 0.9 second in poor lighting; those numbers are good for a digital camera but still perceptible pauses. It typically takes about 2 seconds to recoup between one shot and the next, an interval that rises to 3 seconds with flash. This model's a pretty zippy raw shooter, however, at just less than 3 seconds from shot to shot, it delivers the fastest raw shooting we've seen in a snapshot camera. Its burst mode isn't quite as speedy, ranging between 1fps and 2fps, depending upon the settings.

Given its small LCD and limited zoom range -- a digital camera's display and zoom generally consume the most power -- you'd think that the S70 would have exemplary battery life. Not so. Its 720mAh lithium-ion battery barely eked out 226 shots and one movie clip before dying. A second test finessed that up to 262 shots but with only 38 percent of those using the flash (we usually aim for 50 percent). That may sound like a lot, but you'll probably get worse battery performance in real-world usage, and a camera in its class should be able to sustain power for at least 500 shots.

The zoom operates a bit slowly and frequently overshoots a bit before snapping into one of its predefined increments. It's also fairly noisy. Once you have your scene framed, however, it focuses relatively quickly. There's a bit of barrel distortion at the widest-angle zoom but no more than we've seen with other cameras. As with other cameras, when using manual focus, a magnified view of the subject appears on the LCD. However, it's very difficult to judge focus on the small but otherwise bright and sharp display. At least the display reveals almost 100 percent of the scene; the optical viewfinder shows only 80 percent.

Image quality
In general, the Canon PowerShot S70 takes excellent photos, properly exposed and sharp, with neutral, accurate colours. At the camera's best light-sensitivity setting, ISO 50, the photos display very little noise; at ISO 100, there's a bit more but not enough to seriously impact the overall image quality. At ISO 200 and 400, however, the noise became obtrusive.

The S70 delivers very sharp results in the centre of the image.

Unlike its sibling, the S60, which uses the same lens but a different sensor, the S70 exhibited minimal purple fringing. However, the lens's sharpness falls off toward the left side of the scene, which means that high-contrast edges in the upper-left corner become a potential trouble spot for fringing.

With manual white balance, the S70 produces very neutral grays. And using the tungsten white-balance preset in our test scene yielded fairly neutral, if slightly cool, results. The auto white balance works fairly well in natural light, but as usual with Canon cameras, the S70 delivered very orange images under tungsten lights.

Additional editing by: Guy Cocker