Slimline

Introduced four years after the previous S-series model (the S80), Canon's PowerShot S90 IS presents as the smallest, slimmest and lightest digicam on the market to offer an Advanced suite of shooting modes plus raw file capture. Equipped with the same 10-megapixel CCD sensor as the PowerShot G11, the S90 boasts a fast (f/2.0), stabilised 3.8x zoom lens and a 3-inch PureColor II high-resolution monitor.

At an RRP of $799, the S90 is pretty pricey for a digicam. But it's not cheap to pack a comprehensive suite of controls into a 100 x 58.4 x 30.9 mm body that is small enough to slip into a shirt pocket. The new model offers some significant advances on the feature set offered by its predecessor but falls behind in burst shooting speeds, as shown in the table below.

Build and Ergonomics
Designing an enthusiasts' camera with such a small form factor is challenging and compromises have been inevitable. Some innovative work-arounds have resulted, making the S90 an interesting camera to use. However, if you wish to take full advantage of the camera's capabilities you'll need to study the user manual carefully to find out how everything works.

Compared with its predecessor, the S90's styling is unadorned. The body is a rectangular metal shell with rounded ends and plastic top and bottom panels, reminiscent of the PowerShot SX200 IS model but much more refined. All exterior surfaces are low-gloss black.

The PowerShot S90 (left) and its predecessor, the PowerShot S80 (right), showing the change in styling. (Source: Canon.)

No finger notches are provided beyond a small thumb rest on the rear panel so you must rely on the wrist strap to keep the camera from hitting the ground if it slides from your grasp. (This isn't as unlikely as it may seem, due to the small size of the camera and its smooth and slippery finish.)

Front view of the PowerShot S90 IS with its flash raised. (Source: Canon.)

The front of the S90 is dominated by the lens, which is fast for a slimline digicam. However, its maximum aperture of f/2 at the wide position drops dramatically to f/4.9 at full optical zoom. Field-of-view coverage is equivalent to 28-105mm on a 35mm camera. The table below shows how the lens stops down as it is zoomed in on subjects.

Surrounding the lens is a brand new Control Ring, the operations of which are described in the Controls section below. The only other features on the front panel are the small, circular LED light and the single-hole microphone below it. The Light is used as an AF-Assist beam and also operates as both a red-eye reduction lamp and self-timer indicator.

Two thirds of the rear panel is covered by the 3.0-inch colour LCD monitor, which boasts high resolution (approximately 461,000 dots) plus a wide viewing angle. No viewfinder is provided and it can be difficult to ‘read' the monitor in bright outdoor lighting because the screen is fixed in place. Right of the monitor is the standard Canon control array, consisting of four buttons surrounding a Control Dial which, in turn, surrounds an arrow pad. 

Rear view of the PowerShot S90 IS. (Source: Canon.)

The top left button provides a Short Cut to a pre-set function, chosen from a sub-menu that includes settings like Face detection, ISO, metering modes, white balance, manual white balance measurement, AF mode, in-camera red-eye correction, iContrast and AE/AF locks. Only one function can be registered to this button.

There are other ways to adjust some of these controls so it makes sense to select an option that is buried in the menu, such as the iContrast or AE/AF lock adjustment. Most of the remaining functions are easily accessed via the Func./Set button or used infrequently enough to make toggling through the menu a very minor concern.


Setting the Shortcut button function.

In playback mode, the shortcut button defaults to a Direct Printing control and no other functions can be assigned to it. The playback button is adjacent to the shortcut button and accesses all playback functions for both stills and video clips. Below the Control Dial are the Display and Menu buttons, whose functions are largely self-explanatory.

The arrow pad has a central Func/Set button plus directional rockers that access the exposure compensation, flash, self-timer and macro/manual focus modes.  The exposure compensation arrow doubles as a Jump button in playback mode, while the self-timer arrow provides single image deletion.

A small mode dial is located close to the rear right corner of the top panel. To its left is the shutter button, which lies flush with the camera body and is surrounded by the zoom lever. The Ring Func. button and On/Off switch sit between the shutter button and the pop-up flash, none of them protruding above the camera body.

The top panel of the S90IS.

The flash pops up automatically in dim lighting unless the flash off setting is selected via the arrow pad and you must be careful not to have your finger on it when it begins to move. This means holding the camera between the thumbs and index fingers of both hands with the thumbs under the base plate and the tips of the fingers on the rear edge of the top panel. It's not the most comfortable position for shooting - and even less convenient for adjusting camera settings.

The flash is lowered automatically when the camera is switched off or the flash mode is set to off. The flash range is from about 50 cm to 6.5 metres at the wide-angle position and from 50 cm to 2.5 metres at full tele zoom.

A loop for the wrist strap is located half way down the right side panel. Above it is the HDMI terminal and below it the A/V Out port, which doubles as a mini USB terminal. The rechargeable lithium-ion battery and memory card slot share a compartment in the base panel. A metal-lined tripod socket sits to the left of this compartment.

Controls
 The Control Ring surrounding the lens is used as a step zoom control in the Auto shooting mode. Click-stops provide an easy way to set 35mm, 50mm and 85mm equivalent interim focal lengths. In the Av and M modes, the Control Ring defaults to adjusting aperture settings, swapping to shutter speeds in the Tv mode. However, these aren't the only options.

Options provided by pressing the Ring Func button on the top panel.

Pressing the Ring Func button on the top panel lets you re-set the function assigned to the control ring. Options include Std (the default), ISO, exposure compensation, white balance and step zoom. The Control Dial on the rear panel is used in conjunction with the Control Ring for selecting settings. It takes a while to become accustomed to using these controls together but they do provide a quick way to adjust key settings on-the-fly, particularly when you'd like to fine-tune white balance settings.

Selecting white balance adjustment via the Ring Func button.

Fine-tuning colour balance with the Control Ring.

The mode dial appears to be designed to be operated with the thumb and is quite stiff to move. Click stops are provided for each of the nine settings, which are based on the Canon principle of providing several Basic Zone modes with high levels of automation plus Creative (P, Tv, Av, M and Custom) Zone adjustable modes. Basic Zone modes on the S90 include Auto, Low Light, Special Scene and Movie mode.

Aperture settings are as you'd expect in an Advanced digicam, with the smallest aperture fixed at f/8 but adjustments in 1/3EV up to that point from the widest aperture setting. They are displayed as a linear scale on the monitor in Av mode. The usable range is shown in black but it switches to grey at the left hand end of the scale as the lens is zoomed in, providing a reminder of how much ‘speed' is sacrificed at longer focal lengths.

Shutter speeds range from 15 seconds for the longest exposures to 1/1600 second for the shortest. A similar linear scale to the aperture display appears on the monitor in Tv mode, allowing users to select from the entire range. In manual mode, you must set the Ring Func. to Std so the Control Ring can be used for adjusting aperture while the Control Dial is used for shutter speeds.

Auto bracketing is offered as one of the options in the Function menu but only across three shots. Users can adjust the bracketing range through +/- two stops in 1/3EV increments, allowing limited scope for HDR photography. Focus bracketing is also provided in the same sub-menu, again for three shots over different distances, set by pressing the Display button.

Focusing options are reasonably generous, although most settings must be accessed via the main menu. You can choose between Centre and Face AiAF modes and set the AF frame size to small when precision is required. Half-pressing the shutter button magnifies the AF frame for focus checking when AF Point Zoom is selected in the menu.

The AF lock is located on the arrow pad in the MF mode. It's engaged by half-pressing the shutter button and then pressing the MF button. The S90 also provides a Servo AF mode for shooting moving subjects. The Face Select function lets you register a subject's face so the camera will track it within a certain distance range. Up to 35 faces can be detected in a scene in Face Select mode. Manual focusing is also available, with adjustments via the Control Ring.

The menus are the same as other Canon digicams, with separate pages for shooting/playback, camera settings and My Menu registrations. Most items are adjustable in the Creative Zone modes; the other modes are more restricted. Unlike the G11 (which provides a top panel dial), sensitivity settings must be adjusted via the Func. Set button, which displays a linear scale on the monitor, as shown below.

Adjusting sensitivity via the Func. Set button.

Displays are easily customised with the Custom Display setting in the shooting menu. Users can opt for ashooting info, grid lines, a 3:2 aspect ratio guide or a brightness histogram - or any combination of them. The histogram is only displayed in the P, Tv, Av and M shooting modes. To turn off a display setting, simply select it and press the Func/set button.


Custom Display options.

Sensor and Image Processing
From its specifications, it looks as if the sensor in the S90 (and also the PowerShot G11) is the new ICX685CQZ  CCD chip from Sony Semiconductor. Developed to provide high sensitivity and wide dynamic range, it boasts 2.03 micron square photosites and has a diagonal measurement of 9.31 mm. This sensor is coupled to Canon's DiG!C 4 image processor chip, which is used in most of the company's recent digicams.

As mentioned, the PowerShot S90 supports both JPEG and CR2.RAW file capture and raw files can be recorded with a Large/Fine JPEG file when Record RAW+L is set to On in the main menu. The RAW setting must also be selected via the Func/Set menu or only JPEGs will be captured.

Setting the S90 to record RAW+JPEG files.

Raw files are losslessly compressed and convertible into JPEG or TIFF files with the supplied software. The digital zoom and digital teleconverter functions are disabled for raw file capture. Except for a single Widescreen (16:9) setting, all shots are recorded with a 4:3 aspect ratio. The sRGB colour space is the only option.

Two compression levels are provided for JPEGs: Fine and Normal. The default setting is Fine but users who wish to swap to Normal compression may do so by pressing the Display button when the image size setting is selected. Typical file sizes are shown in the table below.

Although the sensor claims to have been designed to support high-speed shooting, the S90's buffer memory is pretty small so files must be processed on-the-fly when the continuous shooting modes are used. Consequently, the camera claims a maximum continuous shooting speed of 0.9 frames/second, which is cut back to 0.6 fps when autofocusing is required. Frame rates up to 2.1 fps are promised in Low Light mode (and confirmed in our shooting tests).

Because of the sensor's limitations only two resolution settings are provided for movie clip recording: VGA and QVGA. All clips are recorded at 30 frames/second, using the MOV file format, which combines H.264 image compression with Linear PCM monaural audio recording. Typical recording times for a 2GB memory card are shown in the table below.

Maximum length of video clips is one hour. Recording will stop before this time when the file size reaches 4GB. Use of SDHC cards with speed class of 4 or higher is recommended. The optical zoom is disabled in video mode but the digital zoom function remains usable, although with some deterioration in picture quality. The Colour Swap and Color Accent features are also available and the image stabiliser remains active.

Playback and Software
Pressing the playback button switches the camera to play mode and displays the last shot taken. Users can navigate from one image to the next with the horizontal arrows on the arrow pad or by turning the Control Dial in either direction. The down button on the arrow pad allows shots to be deleted individually
Pressing the Display button toggles through four options: image only, simple shooting data, detailed data and focus check display. When detailed data display is selected, an over-exposure warning is also engaged. A brightness histogram is also provided.

The camera comes with Canon's Digital Camera Solution Disk Version 54.0, which contains Digital Photo Professional and PhotoStitch for Windows and Macintosh plus ZoomBrowser for Windows and ImageBrowser for Macintosh. A Software Guide and Personal Printing Guide are also provided.

Performance
Not surprisingly (since they use the same sensor), the S90 we tested turned in a similar performance to the PowerShot G11 we reviewed. Autofocusing was fast and, in most cases, accurate, even in relatively low light levels. The image stabiliser was as effective as that on the G11, allowing us to use shutter speeds as slow as 1/4 second with 50% success rate and 1/15 second with greater than 90% of shots acceptably sharp.

Exposure metering was consistently accurate in a wide range of shooting situations and the use of iContrast for JPEG shots ensured adequate shadow and highlight detail in most situations. Colours were slightly more saturated than we found in similar shots from the G11, although overall colour accuracy was good. Unfortunately, digital zoom shots were slightly soft and artefact-affected. These subjective assessments were confirmed by Imatest testing.

Imatest showed JPEG resolution able to meet expectations for a 10-megapixel camera. The highest resolution in our tests was recorded at longer focal length settings, and aperture settings had only a slight effect on resolution. Some edge and corner softening was detectable at shorter focal lengths but not at full optical zoom. The graph below shows the results of our tests.

Image quality remained relatively high between ISO 80 and ISO 800. However, beyond that point, the superiority of raw files was evident as resolution of JPEG images plummeted. The graph below shows the result of our Imatest tests at different ISO settings for both JPEG and raw files.

Long exposures at night were noise-free up to ISO 400 and only slightly noise-affected at ISO 800. Slight image softening was detected at this point but images were still usable (albeit with some post-capture sharpening). Beyond ISO 800, noise was quite visible and shots taken with the ISO 3200 setting were noticeably softened, although printable at snapshot size. No colour drifts were seen across the review camera's sensitivity range. Flash exposures showed little noise up to ISO 800 but noise was evident at ISO 1600 and sharpness had declined by ISO 3200.

The zoom lens showed only slight rectilinear distortion at the shortest focal length setting and none was obvious thereafter.  However, its design made it quite flare-prone and coloured fringing was visible in outdoor shots with high-contrast subjects. (An example can be found in the Sample Images section below.)

The auto white balance had the same responses to incandescent and fluorescent lighting as we found with the G11. Fortunately, the presets produced neutral colours with both lighting types.

The review camera powered up in approximately 1.5 seconds and we measured an average capture lag of 0.5 seconds, which reduced to a consistent 0.1 seconds when shots were pre-focused. Shot-to-shot times averaged 2.4 seconds, extending to 3.3 seconds with flash. It took 3.4 seconds, on average, to process and store each Large/Fine JPEG file, 4.4 seconds for each raw file and 5.5 seconds for each RAW+JPEG combo.

Continuous shooting speeds were even slower than we found with the G11. In the standard mode with Program AE exposure, we recorded a burst of 10 Large/Fine JPEGs in 8.8 seconds, which took 3.6 seconds to process. Swapping to Low Light mode reduced the size of each file to 1824 x 1368 pixels and allowed the camera to capture 10 shots in four seconds. This burst was processed in just under two seconds.

With raw file capture, the camera was able to record five shots in 8.1 seconds. It took 4.9 seconds to process this burst. For RAW+JPEG shooting, the camera captured five pairs of shots in 14 seconds and took 5.3 seconds to process and store the burst. Adding flash produced only a slight slowing of capture rates but no extension of processing times.

Buy this camera if:
- You want an ultra compact camera that can record raw files and is small enough to fit in s shirt pocket.
- You want effective image stabilisation.
- You'd like most of the controls and functions offered in serious DSLR cameras.
- You require high resolution and low noise levels at ISO settings up to 800.

Don't buy this camera if:
- You'd like the ability to shoot HD video clips. (The S90 supports VGA and QVGA only.)
- You require high burst speeds and buffer capacity plus fast cycle times for processing shots.
- You have large hands or fingers or limited dexterity.

IMATEST GRAPHS

For JPEG files.

For CR2.RAW files processed with Digital Photo Professional.

SAMPLE IMAGES

 
Auto white balance with incandescent lighting.

 
Auto white balance with fluorescent lighting.

 
6mm focal length, ISO 160, 1/101 second at f/6.3.

22.5mm focal length, ISO 160, 1/251 second at f/6.3.

Digital zoom; 22.5mm focal length, ISO 160, 1/318 second at f/6.3.

Close-up; 6mm focal length, ISO 80, 1/251 second at f/2.2.

Long exposure at ISO100; 15 seconds at f/2.2; 9.2mm focal length.

Long exposure at ISO 800; 15 seconds at f/5.6; 9.2mm focal length.

Long exposure at ISO3200; 8 seconds at f/8; 9.2mm focal length.

 
Flash exposure at ISO100; 22.5mm focal length, ISO 100, 1/60 second at f/4.9.

Flash exposure at ISO 800; 22.5mm focal length, ISO 100, 1/60 second at f/4.9.

Flash exposure at ISO 3200; 22.5mm focal length, ISO 100, 1/60 second at f/7.1.

Coloured fringing and edge softening at short focal lengths; 6mm focal length, ISO 200, 1/501 second at f/7.1.

 
100% crop from the above image showing coloured fringing and edge softening.


Image stabiliser test; 10.7mm focal length, ISO 200, 1/4 second at f/2.8.

10.7mm focal length, ISO 3200, 1/30 second at f/4.

Image sensor: 7.6 x 5.7mm High-sensitivity CCD with 10 megapixels effective
Lens:  6.0-22.5mm f/2.0-4.9 zoom lens (28-105mm in 35mm format)
Zoom ratio: 3.8x optical, up to 4x digital
Image formats: Stills - JPEG (Exif 2.2), CR2.RAW; Movies - MOV (Image Data: H.264; Audio Data: Linear PCM monaural)
Image Sizes: Stills - 3648 x 2736, 2816 x 2112, 2272 x 1704, 1600 x 1200, 640 x 480, Widescreen: 3648 x 2048; Movies - VGA/QVGA at 30 fps
Shutter speed range: 15-1/1600 sec.
Self-timer: Approx. 10 sec or 2 sec delay, custom, Face Self-Timer
Image Stabilisation: Optical (Lens Shift Type), approx 4 stops
Exposure Compensation: +/- 2 stops in 1/3-stop increments
Focus system/range: TTL Autofocus with Single, Continuous, Manual; Face Detect with movie support, Centre, Flexizone modes; Normal: 50cm - infinity, Macro: (W) 5cm - 50cm , (T) 30cm - 50cm
Exposure metering/control: TTL metering; Evaluative, Centre-weighted average, Spot modes
Shooting modes: Intelligent Auto with Scene Detection, P, Tv, Av, M, C, Low light, Special Scene (Portrait, Landscape, Night Snapshot, Kids & Pets, Indoor, Sunset, Night Scene, Fireworks, Beach, Underwater, Aquarium, Foliage, Snow, Colour Accent, Colour Swap, Nostalgic, Stitch Assist)
ISO range: Auto, ISO 80, 100, 200, 400, 800, 1600, 3200
White balance: Auto, Daylight, Cloudy, Tungsten, Fluorescent, Fluorescent H, Flash, Underwater, Custom
Flash modes/range (ISO auto): Auto, on, off, Red Eye Correction, Red Eye Reduction, Slow Synchro, Second Curtain Synchro, FE Lock, Safety FE; 50cm - 6.5m (W), 50cm - 2.5m (T)
Sequence shooting: 0.9 shots/sec; AF Approx 0.6 shots/sec; LV Approx 0.6 shots/sec
Storage Media: SD/SDHC/MMC
Viewfinder: No
LCD monitor: 3.0-inch colour LCD monitor with wide viewing angle (approx 461,000 dots)
Power supply:  NB-6L rechargeable lithium-ion battery
Dimensions (wxhxd): 100 x 58.4 x 30.9 mm
Weight: Approx. 175 grams (without battery and card)