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Canon's PowerShot A650 IS replaces two earlier models, the 10-megapixel PowerShot A640 and 8-megapixel PowerShot A630, bringing higher resolution (12-megapixels), a longer 6x optical zoom lens and optical image stabilisation. It retains the 2.5-inch vari-angle LCD of its predecessors but has a new DiG!C III image processor. It's also 55 grams heavier, with a significantly larger body.

Although designed like its predecessors – and just as solidly built – the test camera felt rather 'plasticky'. The LCD screen rotates through 270 degrees and can be turned to face outwards from the rear of the camera. It's solidly anchored and the monitor fits snugly into the rear panel. We found the cover to the review camera's battery/card compartment difficult to open and close and its hinge looked flimsy. A tether is provided for a wrist strap, although a neck strap would have been preferable.

Based on specifications sheets, this camera appears to have the same sensor and lens as the soon-to-be-released PowerShot G9, which is physically smaller but 20 grams heavier and uses a lighter lithium-ion battery. The G9 is likely to sell for around $100 more and supports raw file capture. It also sports a larger, non-adjustable, 3.0-inch LCD. These similarities make the A650 IS worthy of consideration by serious photographers.

Covering a zoom range equivalent to 35-210mm in 35mm format, the A650 IS's lens retracts into the camera body and is responsible for much of its additional bulk and weight. The built-in lens-shift image stabiliser offers a choice of three modes - continuous, shoot only and panning – plus an off setting that can be used when the camera is tripod-mounted. In continuous mode, users can check the effect of the stabilisation on the LCD monitor. In shoot only mode, stabilisation is only applied when the shutter button is pressed, while in panning mode, the stabiliser only counteracts the effect of up and down movements.

To further reduce the risk of camera shake, Canon has included a special Auto ISO Shift control, which is available in Auto, P and Av shooting modes. This setting is engaged via the menu and boosts sensor sensitivity when potential for camera shake is detected, allowing a faster shutter speed to be set.

For novice users, the easily selected Image Zone settings on the mode dial provide quick access to pre-set modes for shooting portraits, landscapes, night snapshots and pictures of kids & pets, along with a Special Scene mode that covers night scene, indoor, foliage, snow, beach, fireworks, aquarium, underwater and ISO 3200 pre-sets. Completing the shooting modes are a stitch assist mode for shooting panoramas and a movie setting.

Still images can only be recorded in JPEG format but the A650 IS provides six file sizes, one of them a 'widescreen' 4000 x 2248 pixel file. Although three compression settings are provided, when the Hi ISO mode (which reduces resolution) is selected, the resulting image can only be recorded with medium compression. Compression rates are relatively high, as can be seen in the table below.

For movie clip recording, the A650 IS has two shooting modes: Standard and Compact. Three settings are available in Standard mode: VGA quality at 30 fps, a Long Play (LP) mode, which records at the same size and frame rate but produces clips with half the file size, and QVGA quality at 30 fps. Maximum clip length is three minutes in Compact mode. The table below shows the relative file sizes and recording times of the four movie options.

All movie clips are recorded with sound and, because the built-in microphone that records the sound can pick up noises made by the camera, focus and optical zoom settings are locked for the length of each clip. Digital zoom can, however, be used. The camera will adjust exposure and white balance continuously during video capture to compensate for changing conditions. You can record up to 4GB of video with any of the Standard mode settings.

As well as supporting the latest Face Detect technology and in-camera red-eye correction the DiG!C III image processor also enables the camera to include a special ISO 3200 scene mode, which captures images at 1600x1200 pixel resolution. The results are rather noise-affected but printable at postcard size. Canon's Face Detect system has been updated to include flash exposure control to ensure better portrait exposures.

Shutter speed settings range from 15 seconds to 1/2000 second, covering a wider range than most digicams. Noise reduction processing is engaged automatically for exposures of 1.3 seconds or longer. The built-in flash supports and both first- and second-curtain flash sync and flash output is adjustable through +/- 2EV in 1/3-stop increments. A Safety FE mode allows users to set the camera to automatically adjust the aperture or shutter speed when the flash fires to avoid over- or under-exposure.

Otherwise the A650 IS has the standard suite of Canon functions, which include a 9-point AF system with four ways to set the AF frame. Selecting Face Detect, which is only fully available with evaluative metering, automatically identifies human faces and adjusts focus and metering to ensure they are sharp and correctly exposed. If no face is detected, the camera defaults to AiAF, which automatically selects from an array of nine AF frames. Choosing Centre AF fixes the AF frame in the centre of the field of view. In the P, Av, Tv and M shooting modes, the Flexizone setting lets you move the AF frame to any point in the nine point array using the +/- and arrow pad buttons.

You can also adjust the AF frame size in Centre and Flexizone modes to suit the requirements of the subject. Manual focusing is selected via the Macro/Landscape button on the arrow pad. In this mode, a bar at the top of the screen shows the distance settings, which are adjusted with the horizontal buttons on the arrow pad. A central square on the screen provides an enlarged view of the subject so you can see when focus is achieved. You can focus to within 1 cm of subjects with this setting.

Like other A-series cameras, the A650 IS uses four AA batteries and is sold with alkaline cells. These batteries are C.I.P.A rated for approximately 300 shots with the LCD monitor on or 1000 shots with it off or roughly 18 hours of playback time. AA-size NiMH rechargeable batteries can also be used and a fully-charged set will support approximately 500 images with the LCD on, 1400 shots with the monitor off or 19 hours of playback.

Performance
We were concerned that the A650 IS's 12-megapixel imager, which only measures 7.6 x 5.7 mm in area, would deliver noise-affected pictures at moderate and high ISO settings. However, image noise was well controlled throughout the normal ISO range, becoming visible at ISO 800 and starting to impact on image sharpness at ISO 1600. However, colour accuracy remained good through all ISO settings for both long exposures and flash shots. When the ISO 3200 scene mode was used, picture quality was very poor.


Ten-second exposure at ISO 1600.

The same subject photographed with the ISO 3200 scene mode.

Photographs taken with the test camera were bright and colourful with plenty of fine detail, an above-average dynamic range and well controlled saturation. However, Imatest showed resolution to be below expectations but edge-to-edge sharpness was generally good. Some barrel distortion was observed at the widest zoom setting, although it was not enough to affect normal photography.

Imatest showed image resolution to be below expectations - but typical of what we have found in past tests of high-resolution digicams with small sensors. Fortunately edge-to-edge sharpness was relatively consistent, although some barrel distortion was observed at the widest lens setting. However, it was not enough to interfere with normal photography and had vanished by mid-way along the zoom range.

Overall colour accuracy was shown to be good in our Imatest assessments. Slight shifts were detected in cyan and yellow hues. Saturation was marginally elevated across all colour bands but to a lesser degree than in many digicams. Lateral chromatic aberration was low. We found some green, orange and purple fringing in shots taken in bright outdoor conditions but it was not the worst we've encountered by a long chalk. Digital zoom shots were among the best we've seen with no visible artefacts.

An enlarged section of an outdoor shot showing coloured fringing along areas with large differences in contrast and brightness.

We found the test camera's auto white balance system was unable to counteract the orange casts of incandescent lighting but came close to correcting fluorescent lights' green. The manual pre-sets came close to producing neutral colours, while custom measurement was almost spot-on.


Auto white balance with incandescent lighting.

Auto white balance with fluorescent lighting

The test camera was ready for shooting within 1.6 seconds of power-on and closed down in around a second. We measured an average capture lag of 0.6 seconds, which reduced to instantaneous capture with pre-focusing. It took 4.4 seconds, on average, to process a JPEG file at top resolution and quality, although shot-to-shot times averaged just under three seconds without flash and about 3.3 seconds with.  The continuous shooting mode recorded a burst of four Large/SuperFine shots at 0.8 second intervals and it took 6.6 sec to process the burst.

Conclusion
Aside from some reservations we have about the body design, the A650 IS provides an excellent control suit for its price. It's also an affordable choice for photographers who want the benefits of P, Av, Tv and M shooting modes and high resolution and would be an excellent 'learning' camera for prospective DSLR buyers. Ideal for family photographers and travellers, it's worthy of consideration by any amateur photographer who wants a flexible, user-friendly digicam with good performance and a wealth of useful functions.

IMATEST GRAPHS

SAMPLE IMAGES

Close-up

Manual focus at 1 cm from subject

Digital zoom

Image sensor: 7.6 x 5.7 mm CCD with 12.4 million photosites (12.1 megapixels effective)
Lens: 7.4-44.4mm f/2.8-4.8 zoom (35-210mm in 35mm format)
Zoom ratio: 6x optical, 4x digital
Image formats: Stills – JPEG (Exif 2.2) ; Movies - Motion JPEG/WAV
Image Sizes: Stills – 4000 x 3000, 4000 x 2248, 3264 x 2448, 2592 x 1944, 1600 x 1200, 640 x 480; Movies – VGA/QVGA at 30/15 fps
Shutter speed range: 15-1/2000 sec.
Image Stabilisation: optical
Exposure Compensation: +/- 2EV in 1/3 EV steps
Focus system/range: TTL Autofocus plus manual focus; range 50 cm to infinity; macro 1-50 cm
Exposure metering/control: Evaluative, Centre-weighted average, Spot metering; Auto, P, Tv, Av, M, C, Portrait, Landscape, Night Snapshot, Kids & Pets, Special Scene (9 modes), Stitch Assist
ISO range: Auto, Hi ISO Auto, ISO 80, 100, 200, 400, 800, 1600
White balance: Auto, Daylight, Cloudy, Tungsten, Fluorescent (x2), Underwater, Custom
Flash modes/range (ISO auto): Auto, On, Off, Slow-synchro, 2^nd Curtain synch (red-eye reduction available); range 50 cm to 3.5 m
Sequence shooting:  Approx 1.2 shots/sec (Large/Fine)
Self-timer: Approx. 10 sec or 2 sec delay, or custom
Storage Media: SD/SDHC/MMC card
Viewfinder: Real-image optical zoom
LCD monitor: Vari-angle 2.5-inch Low-temperature polycrystalline silicon TFT colour LCD
Power supply:  4x AA batteries (alkaline supplied)
Dimensions (wxhxd): 112.1 x 56.2 x 67.8mm
Weight: Approx. 300g (camera body only)