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Sensor-shift Image Stabilization

The K200D features Pentax' sensor-shift image stabilization system. This system works by moving the sensor in the opposite direction to the sensed shake movement of the camera. To function properly the camera needs to know the focal length of the lens. If you are using a Pentax DA, D FA, FA J, FA or F lens this information is acquired automatically. For all other lens types you can enter it manually in the menu.

The stabilization test

This is our standard in-body IS test. Twenty hand-held shots were taken of a static scene, half of those with stabilization, half without, the shutter speed was decreased by a stop and repeated (from 1/100 sec to 1/6 sec). The lens used was the Pentax 50 mm F1.4 (producing a 75 mm equiv. FOV), the test chart was 1.2 m away from the camera.

The resulting 100 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: Soft' 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 blurred 1: Blurred
2: Soft 3: Sharp

Hand-held, no stabilization (75 mm equiv. FOV)

With the anti-shake system switched off we get 100% sharp images when shooting at 1/100th of a second. Below that, the 'keeper' rate drops off progressively and when shooting at slower speeds than 1/50th of a second we only get 50% or less usable shots (sharp/soft).

Hand-held, with stabilization (75 mm equiv. FOV)

With anti-shake switched on the improvement is immediately visible although you still only get 100% sharp shots at 1/100th sec. On the plus side even at shutter speeds as slow as 1/6th sec you get 50% usable shots. The system gives you an advantage of approximately 2 stops but tends to work more efficiently at very slow shutter speeds. This is a reasonable result but not outstanding. It is also not even close to the the 4 stops that Pentax claims its anti-shake is capable of.

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