iContrast is Canon's method of boosting the apparent dynamic range in the S90's shots. It pulls up darker tones in the image to give a better balanced image when you're shooting in high contrast situations. It does a pretty good job of reducing the blackness of shadows (at the expense of a touch more noise in the midtones), but it won't help those clipped highlights and is irrelevant if you shoot raw (the same effect can be applied with considerably more control at the processing stage).
|iContrast OFF - ISO 80, 1/100, F 4.0||iContrast Auto - ISO 80, 1/100, F 4.0|
Perhaps the biggest disappointment with the S90's basic specification is the movie mode, which - like the G10 and G11 - has only a 30 fps VGA (640x480) mode, which makes it stand out in an era when 720p HD movies are becoming the norm and 'full HD' 1920x1080 isn't unusual. As we understand it this is a limitation of the sensor (rather than a decision by Canon to restrict the S90's movie abilities).
Once again the S90 has just three modes available while showing movies: Standard, Color Accent and Color Swap. The S90 encodes its videos using H.264 encoding method, rather than the more common but less efficient Motion JPEG system.
That all said, the picture quality is excellent, and if you have no need for High Def movie capture and just want to share clips via email or YouTube, the S90 is perfectly capable.
Optical image stabilization
The S90 features Canon's lens based image stabilization system. With a 35mm equivalent focal length of 105mm at the long end of the zoom on the S90 lens shake is less of an issue than on a big zoom camera but nevertheless an efficient stabilization system can be useful at any focal length.
There are three modes: Continuous (IS on all the time), Shoot only (IS is activated at the moment the exposure is made) and Panning (for horizontally panned shots).
The first option makes framing easier - the IS system steadies the preview image, and we found it more consistently effective at extremes (where the shutter speed is more than 3 stops slower than would normally be necessary for the focal length you're shooting at) than the Shoot only mode. Shoot only - which doesn't steady the preview image - uses less battery and still offers a considerable improvement over no IS.
The S90's stabilization system does a decent job in most shooting situations. The effectiveness of the system will differ from one photographer to another but typically - when not pushed to extremes - it'll give you somewhere around a 2 stop advantage. At the short end of the zoom (28mm equiv.) the need for IS is pretty minimal (especially with an F2.0 lens to play with), but at the long (105mm) end you will see a slight increase in the number of usable shots even at shutter speeds as low as 1/8th second, and at 1/30th second we were getting almost 100% sharp shots.
|IS off, 1/8 second 105mm (close up), 100% crop|
|IS On (continuous), 1/8 second 105mm (close up), 100% crop|
The Canon IS does not do any miracles but it helps a lot, and can significantly increase your chances of getting a usable shot in low light situations. It's quite useful in movie mode too, your footage will be visibly less jerky when the system is activated.