Canon PowerShot A570 IS Full Review
The optical image stabilization system used on the A570 IS works well. The Camera has three modes: Continuous (IS on all the time), 'Shooting' (stabilization is only activated when the button is half-pressed to lock exposure) and 'Panning' (only stabilizes the effect of vertical camera shake, for photographing horizontally moving objects). Continuous mode makes framing easier - the system steadies the preview image - but obviously uses more battery power (it's on all the time).
The system makes handheld shots at 2 even 3 shutter speeds slower than normal perfectly possible, though beyond 1 stop it's nowhere near 100% reliable. The 100% crops below show the effectiveness of the IS system when shooting at longer focal lengths at speeds as low as 1/20th sec.
|Real world example: 140mm (equiv), 1/20th Second, hand-held|
|Stabilization off||Stabilization on|
The stabilization test
In this simplified version of our SLR IS test, ten hand-held shots were taken of a static scene with the stabilization off and on. The shutter speed was decreased for each shot (from 1/200 sec to 1/13 sec). The zoom was set to its maximum position (140mm equiv.), the test target was 2.5 m away from the camera. The test was repeated 3 times and an average taken.
The resulting images were then inspected and given a blur score - 'Sharp' (no visible blurring at 100%), 'Mild Blur' (the kind of camera shake that is tolerable at small print sizes) and 'Heavy Blur' (virtually unusable due to camera shake) and 'Very Heavy Blur' (little discernible detail).
As the charts below show the IS system does give you a couple or even three stops advantage. At two stops below the recommended minimum shutter speed (using the focal length reciprocal rule of thumb) you still get 100% usable shots. At three stops below 80% of shots are either sharp or only mildly blurred.
Hand-held, no stabilization (140mm equiv.)
As you can see from the chart below only at 1/200th sec or above can we be confident of getting sharp results from the majority of shots, and once you get to 1/25th sec and below the majority of shots are heavily blurred, and none are sharp.
Hand-held, stabilization on (140mm equiv.)
With stabilization on the results are significantly better - we got sharp or only mildly blurred shots at all shots down to 1/50 sec. If you're shooting at three stops below the recommended minimum shutter speed you have a one in five chance of getting a completely sharp and an 80% chance of getting an at least acceptable image.
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