Pentax has established itself amongst the camera manufacturers that provide image stabilization built in to its cameras, rather than making it a feature of lenses (and there are convincing arguments for both approaches). Its system is still the only fully 'free floating' design which allows it to correct for not only movement on the x and y axis but also rotation on the z axis (the twisting motion around the optical path), so it'll be interesting to see whether this is noticeable in our tests.
The stabilization test
In order to conduct this test, twenty hand-held shots were taken of a static scene, half of those with stabilization, half without, the shutter speed was decreased by one third of a stop and repeated (from 1/100 sec to 1/3 sec). The lens used was the Pentax 50 mm F1.4 (producing a 75 mm equiv. FOV), the test chart was 2 m away from the camera.
The resulting 320 images were then inspected and given a blur score from zero to three where zero represented a very blurred image and three a sharp image with no noticeable blur (see crop examples below). Obviously the amount of blur which is acceptable will depend on your personal taste and the final image size (for instance a '2: Mild blur' will still look fine as a 4x6 print or in a web gallery). Example crops from these four blur scores can be seen below.
|0: Very heavy blur||1: Heavy blur|
|2: Mild blur||3: Sharp|
Hand-held, no stabilization (50 mm lens, 75 mm equiv.)
As you can see, when the shutter speed drops below the traditional guide for hand-holding (shutter speed=1/equivalent focal length), the number of completely sharp shots drops off dramatically.
Hand-held, with Shake Reduction (50 mm lens, 75 mm equiv.)
Turning shake reduction on substantially improves this performance, with a similar number of sharp shots being achieved at 1/13th of a second with SR on as were being achieved at 1/50th with it turned off. And again, one stop slower than these two settings (1/25th and 1/6th), shake reduction is out-performing simple hand-holding at a shutter speed four times as long. It's reasonable to expect that shake reduction will give stable, sharp shots at shutter speeds two stops slower than you'd get without.