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Replacing the PowerShot SX10 IS at the top of Canon's super-zoom range, the PowerShot SX20 IS has higher resolution than its predecessor and includes the ability to record video clips in widescreen, high-definition (1280 x 720 pixel) format. Otherwise, little has changed in the new model. With its SLR-like styling and large hand-grip, the SX20 IS is targeted at photo enthusiasts who want a cheaper, more compact camera for travelling - or even everyday use.

Front view of the PowerShot SX20 IS. (Source: Canon.)

Rear view of the PowerShot SX20 IS, showing the vari-angle LCD monitor. (Source: Canon.)

Angled view of the PowerShot SX20 IS with the zoom lens fully extended. (Source: Canon.)

The camera body is the same as the SX10 IS (and its ‘sister' model, the SX1 IS); so is the 20x optical zoom lens and vari-angle 2.5-inch LCD monitor, which retains the relatively low 230,000-dot resolution. The viewfinder is dioptre-adjustable and has the same resolution as the previous mode. Also carried over is the DiG!C 4 image processor, which means many camera functions are unchanged.

The mode dials on all three models are identical, as is the layout of most button controls. We've already provided details of the physical aspects of the SX20 IS's body in our review of the PowerShot SX1 IS so there's little point in repeating them. Click here to access this review.

One feature that bears repeating is a reminder that the 5mm to 100mm Canon lens on all three models is equipped with the same ultrasonic motor (USM) and voice coil (VCM) motor technologies as Canon's DSLR lenses. Accordingly, it provides fast and almost silent zooming, which will come in handy for anyone who shoots wildlife or sports. The addition of a 4x digital zoom setting provides potential for extension (albeit with some loss of image quality) when need arises.

Complementing the lens's extended focal length is Motion Detection, which was introduced with the DiG!C 4  chip. It works in parallel with the IS system to minimise blurring due to subject movement. While useful for wildlife photographer, both functions will be appreciated by macro photography enthusiasts using the ‘zero macro' setting, which enables users to capture subjects at almost 1:1 magnification. 

The Intelligent Auto Technology that forms the third part of Canon's TruCapture technology is also provided in the SX20 IS. Designed to ensure consumers get the shot they want first time, every time, this trio of technologies also includes optical image stabilisation and the DiG!C Colour Processor. All combine to provide sharp, colour-accurate pictures, with the Intelligent Auto shooting mode including:
-  Scene Detection, which can match camera settings to the requirements of up to 22 scene types (e.g. Portrait, Night, Macro, Backlit or Sunset) and then apply optimum image processing for that scene.
- Advanced Face Detection, which recognises when faces are included in a scene and will indicate them. A white frame is placed around the main subject, while grey frames appear around other detected faces. 
- Motion Detection. If the main face moves, the white frame will follow it, while the grey frames will disappear. Half-pressing the shutter button turns the face detection frames green when the subject is in focus.  
- Noise Reduction processing to minimise the visibility of noise in shots taken with high ISO settings.

Sensor
The sensor used in the SX20 IS is a standard 1/2.3-inch type (6.16 x 4.62 mm) CCD chip with a total of 12.4 million photosites and an effective resolution of 12.1 megapixels.  For 4:3 aspect ratio images, the effective pixel count is approximately 10-megapixels, while cropping to produce the 16:9 aspect ratio results in approximately 8.30 million pixels (effective). The pixel pitch is 1.7 mm and the standard primary colour filtration is used (presumably with a Bayer pattern).

Although the camera supports sensitivity settings ranging from ISO 80 to ISO 3200, the highest setting is only available as a Scene pre-set - where shutter speeds and aperture adjustments aren't supported. This is probably a good strategy since we found image quality deteriorated with this setting to such an extent that shots became essentially unusable. Colour accuracy and sharpness were both seriously compromised. (Examples can be found in the Sample Images section below.)

The SX20 IS only records still images as JPEGs, offering six image size settings (including one 16:9 'widescreen' option).  Unlike the SX10 IS, which provided three compression levels, the new model only offers Fine and Normal compression.

As in the SX10 IS, while image size continues to be adjustable via the Function menu, to adjust compression you must press the Display button after setting the image size and then use the rotating dial to move between Fine and Normal. (This button also toggles between LCD and EVF and adjusts display modes.)

Compression levels are significantly higher than those in the SX20 IS. Typical image sizes are shown in the table below.

However, where the SX10 IS is restricted to VGA and QVGA video recording at 30 frames/second, the SX20 IS adds the ability to record High Definition (1280x720) movies at 30 frames/second with stereo sound, captured through two microphones located just below - and on either side of - the pop-up flash. Use of the H.264 video compression standard provides good video quality at lower bit rates than previous system, providing greater recording times for memory capacities. Typical recording capacities are shown in the table below.

Like the SX10 IS, the SX20 IS allows you to initiate movie recording from any shooting mode by simply pressing the large button on the rear panel. A second push stops recording. Recording will stop when the file reaches 4GB.

You can use the optical zoom while recording video clips.  Autofocusing continues while video is being captured and adjustments will be made to exposure levels and white balance, if required. Face detection also engages automatically. 

You can capture still images while shooting a video clip by simply pressing the shutter button. Focus and exposure will be adjusted, although no beep will sound to indicate the shot is in focus. The shutter sound and black screen that marks the still capture is recorded in the video clip.

If you're shooting video at 1280 x 720 resolution, still images will be recorded in the Widescreen size, at 3840 x 2160 resolution. For some inexplicable reason, still pictures captured when shooting VGA or QVGA video are recorded at 4000 x 3000 pixels, even if you have set the camera to Widescreen capture.

Other Features
The mode dial is split into the same Basic and Creative zones as Canon's DLSR cameras - although they're not labelled as such. The former include the Auto and various Scene mode settings as well as the Stitch Assist mode (for shooting panoramas) and the movie mode. Among the Creative zone settings are the P, Tv, Av  and M shooting modes, which support manual exposure adjustments. An additional C mode provides a memory in which users can register frequently-used modes and settings.

Pressing the FUNC/SET button opens a sub-menu in which you can adjust white balance, My Colours settings, bracketing, flash output levels, the metering pattern, drive mode and image resolution (size). The regular Menu button accesses 21 shooting settings and 17 set-up controls. You can upload one of your own pictures aas the start-up image and change the sounds played back for various camera functions. A page is also provided for registering your own My Menu settings in a separate section of the menu.

The SX20 IS is supplied with four alkaline batteries but will also accept rechargeable NiMH cells. Using rechargeables provides both practical and environmental benefits, as shown in the battery life table below.

Playback and Software
Pressing the button indicated by an arrow changes the camera to playback mode and the last shot taken is displayed on the monitor. You can toggle through shots with the horizontal buttons and the camera supports single, 12-frame index and video playback, playback zoom of up to 10x, focus check playback (with magnification), slideshows with three selectable transition effects and the standard range of Jump options.

The remaining playback functions include the ability to erase or protect single shots or a selection of images, allocate images to categories, resize, rotate and trim images, add sound memos up to a minute long to selected shots or apply red-eye corrections. Both i-Contrast and My Colours adjustments can be applied to images in playback mode.

You can customise display information to include the shooting information you require or overlay grid lines or a 3:2 aspect ratio guide. Brightness histograms can be displayed in the P, Tv, Av and M shooting modes. One selected function can be registered to the Func/Set button for quick access and groups of frequently-used settings can be registered in the My Menu settings tab. Images can also be tagged for automatic printing via a dedicated Print menu and the camera is fully PictBridge compatible.

The software bundle provided on Canon's Digital Camera Solution Disk includes an electronic version of the full user manual in PDF format plus the latest versions of ZoomBrowser EX (Windows) and ImageBrowser (Macintosh) for organising and editing images, movies and slideshows, or creating and printing digital photo albums. A Personal printing Guide is also provided, along with the PhotoStitch panorama stitching application.

Performance
Pictures taken with the test camera were slightly soft straight out of the camera but files were relatively clean and colourful. Pastel colours retained the required degree of tonal subtlety and primary colours were strong and bright with the slightly elevated saturation that typifies compact digicams. Although exposure levels were pitched for even coverage of shadows and highlights, the dynamic range in shots of contrasty subjects was limited, as you would expect from a digicam with such tiny photosites.

Imatest showed resolution to be slightly below expectations and revealed some edge softening, particularly at the shortest focal lengths. Best performance was at the shorter focal lengths and with wider lens apertures. The graph below shows the results of our tests.

Resolution was highest at ISO 80, although the differences between ISO 80 and ISO 100 were negligible. A decline began at ISO 200, although acceptable levels were retained up to ISO 800, with a sharp decline at ISO 1600. The ISO 3200 mode produced images with such low resolution that differences between centre and edge sharpness were minimal. The graph below shows the results of our tests.

Low-light performance was variable. Image noise became visible in long exposures from ISO 400 on and both pattern and colour noise were evident in shots taken at ISO 1600. Shots taken at ISO 3200 were dark, unsharp and blotchy. The flash proved able to illuminate an average-sized room at all ISO settings and flash exposures were evenly balanced across the ISO range. Less noise was evident in flash shots at high ISO settings than in long exposures, although images taken at ISO 3200 remained largely unusable.

Imatest showed colour accuracy to be fair, with elevated saturation in the red and blue sections of the spectrum. Light skin hues were shifted to slightly warmer than natural levels. Shifts were also seen in cyan and blue hues.

Lateral chromatic aberration remained mainly at the low end of the ‘moderate' band in our Imatest tests. Its presence was confirmed by both purple and green fringes in many test shots (shown in the Sample Images section below). Fringing was apparent with both the wide and telephoto focal lengths and it was more pronounced towards the edges of shots than near the centre.

Close-up performance was competent and excellent results can be obtained with the camera's ‘zero macro' setting, which will focus on subjects that almost touch the front element of the lens. However, care must be taken to prevent the rather large lens from shading the subject in this mode.

Barrel distortion was obvious in wide-angle shots but became negligible at a focal length of around 15mm. Very slight pincushioning could be detected at the 50mm focal length setting. Digital zoom shots were sharp and less artefact-affected than we normally see but the limited dynamic range of the sensor tended to compromise highlight areas.

Movie quality was similar to the SX1 IS.  Clips looked  good at the 1920 x 1080 pixel setting but less impressive (although still adequate) at lower resolutions, particularly in dim lighting where noise was evident. The quality of the stereo audio was also a cut above average and almost on a par with a typical digital camcorder. 

The auto white balance failed to eliminate the orange cast of incandescent lighting but produced close-to-neutral colours under fluorescent lights. The tungsten pre-set over-corrected slightly but the slight casts from the three fluorescent settings were easily correctable with editing software. Manual measurement delivered neutral colours with both types of lighting.

Overall response times were about average for the latest digicams. The test camera powered up ready for shooting in approximately 0.7 seconds and shot-to-shot times averaged 1.7 seconds without flash and approximately 3.2 seconds with. On average, it took 3.1 seconds to process each image file.

We measured an average capture lag of 0.5 seconds, which was reduced to a consistent 0.1 second lag when shots were pre-focused. The continuous shooting mode recorded 5 shots in 3.6 seconds. Image processing appears to be on-the-fly as it took only 3.6 seconds to process each burst of 5 shots. The alkaline batteries supplied with the test camera still had power remaining at the end of our tests, which involved 156 shots.

Buy this camera if:
- You're looking for an ultra-zoom digicam that can record widescreen high-definition video with stereo sound.
- You want plenty of adjustable controls and image stabilisation.
- You'd enjoy taking very close ‘macro' shots.
- You prefer cameras that use AA batteries.

Don't buy this camera if:
- You want a pocketable camera.
- You prefer shooting raw files as well as JPEGs and RAW+JPEG pairs.
- You need a camera that can record a wide dynamic range in outdoor shots.
- You require high performance levels in dim lighting, particularly for long exposures.

IMATEST GRAPHS

SAMPLE IMAGES

Auto white balance with incandescent lighting.

Auto white balance with fluorescent lighting.

Close-up. 5mm focal length, ISO 100, 1/60 second at f/4.5.

‘Zero macro' mode; 5mm focal length, ISO 100, 1/1244 second at f/4.5.

‘Zero macro' mode; 5mm focal length, ISO 80, 1/1244 second at f/3.5.

5mm focal length, ISO 100, 1/515 second at f/5.7.

100mm focal length, ISO 100, 1/403 second at f/5.7.

Digital zoom. 100mm focal length, ISO 100, 1/403 second at f/5.7.

5mm focal length, ISO 100, 1/807 second at f/5.7.

 
Coloured fringing in a 100% crop from the above image.

ISO 80, 15 second exposure at f/2.8; 8.6mm focal length.

ISO 1600, 10 second exposure at f/5.6; 8.6mm focal length.

Night shot taken with the ISO 3200 Scene mode: 1/8 second exposure at f/2.8; 8.6mm focal length.


Flash exposure; 23.8mm focal length. ISO 100, 1/60 second at f/4.5.

Flash exposure; 23.8mm focal length. ISO 1600, 1/60 second at f/4.5.

Flash exposure taken with the ISO 3200 Scene mode; 23.8mm focal length, 1/60 second at f/4.5.

Dynamic range coverage; 100mm focal length, ISO 100, 1/1002 second at f/5.7.

Extreme backlighting. 100mm focal length, ISO100, 1/2004 second at f/8.

Flare: 5mm focal length, ISO 80, 1/1244 second at f/5.

100mm focal length, ISO 250, 1/318 second at f/5.7.

Image sensor: 6.16 x 4.62 mm CCD with 12.4 million photosites (12.1 megapixels effective)
Lens:  5-100mm f/2.8-5.7 zoom lens (28-560mm in 35mm format)
Zoom ratio: 20x optical, up to 4x digital
Image formats: Stills - JPEG (Exif 2.2); Movies - MOV (Image Data: H.264; Audio Data: Linear PCM monaural/stereo)
Image Sizes: Stills - 4000 x 3000, 3264 x 2448, 2592 x 1944, 1600 x 1200, 640 x 480 (10245), Widescreen: 3840 x 2160; Movies - HD 1280x720, 640x480, 320x240, all at 30fps
Shutter speed range: 15-1/3200 seconds
Self-timer: Approx. 10 sec or 2 sec delay, Custom, Face Self-Timer
Image Stabilisation: Optical (Lens Shift Type), approx 4 stops
Exposure Compensation: +/- 2EV in 1/3EV increments
Focus system/range: TTL Autofocus with Single, Continuous, Manual modes; Face Detect with movie support, Centre, Flexizone AF; 50cm - infinity, Macro: 10cm - 50cm, Super Macro: 0cm - 10cm
Exposure metering/control: TTL metering with Evaluative, Centre-weighted average, Spot modes
Shooting modes: Intelligent Auto (with Scene Detection), P, Tv, Av, M (Manual), C (Custom), Portrait, Landscape, Night Snapshot, Sports, Special Scene (Indoor, Night Scene, Sunset, Foliage, Snow, Beach, Fireworks, Aquarium, ISO 3200, Color Accent, Color Swap), Movie
ISO range: Auto, ISO 80, 100, 200, 400, 800, 1600
White balance: Auto, Daylight, Cloudy, Tungsten, Fluorescent, Fluorescent H, Flash, Custom
Flash modes/range (ISO auto): Auto, on, off, Red Eye Correction, Red Eye Reduction, Slow Synchro, Second Curtain Synchro, FE Lock, Safety FE; range - 50 cm to 6.8 m
Sequence shooting: Approx 1.0 shots/sec; AF Approx 0.7 shots/sec; LV Approx 0.8 shots/sec
Storage Media: SD/SDHC cards
Viewfinder: EVF with dioptric adjustment and 5 levels of brightness adjustments
LCD monitor: 2.5 inch vari-angle LCD monitor with approx 230,000 dots
Power supply:  4x AA batteries; the supplied alkaline batteries are CIPA rated for approx. 340 shots with LCD monitor on; NiMH batteries ate rated for approx. 600 shots
Dimensions (wxhxd): 124 x 88.3 x 86.9 mm
Weight: Approx. 560 grams (without batteries and card)