Optical image stabilization
The optical image stabilization system used on the SD700 IS is the same as that used in the popular S2 IS and S3 IS superzoom models, and it works very well, though - as ever - don't expect miracles. 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, though in our tests it wasn't as effective as the Shoot only mode. Shoot only, which doesn't steady the preview image, is theoretically more efficient because it minimizes the amount of corrective movement required by waiting until the instant the picture is taken. We certainly found the 'shoot only' option to work more consistently, and we saw little, if any, camera shake in our everyday shots taken for the gallery.
With short zooms like this (max focal length 140mm equiv.) image stabilization is considerably less essential than with a 10x or 12x 'super zoom'. At anything over about 1/125th sec you're not going to suffer from camera shake a great deal. At the short end of the zoom it becomes a problem at around 1/15th sec (depending on how steady-handed you are), and we've yet to see a system that can fully correct at shutter speeds below about 1/4 sec, giving you at best a two stop advantage. That said, we found it perfectly possible to shoot at 1/15th sec at the long end of the zoom (a 3 stop advantage over non stabilized shooting) and - nine times out of ten - at 1/4 sec at the short end (again, a good 3 stops better than without the IS), so it's worth having. It also makes for much less jerky movies.
Although we've no definitive test for IS systems in real-world use, I was very impressed with the SD700's system, though I'm increasingly convinced that it isn't quite as effective as that used on Panasonic's Lumix range. Of course the more megapixels in the image, the more you're likely to see any blur (viewed at 100% on-screen).
These tests are rather extreme - up to five stops slower than you could safely use without IS - and in 'real life' shots - where you are maybe using a shutter speed two stops slower than normal - the system is pretty much 100% effective.
|1/10th second, hand-held, 140mm (equiv.)|
|IS on ('shoot only' mode)||IS off|