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Image Stabilization Test: Olympus E-520 SLR body

Olympus was a pioneer of sensor-based image stabilization (IS) systems, so it was with great interest that we evaluated the IS performance of their E-520 SLR body.

In the film world, image stabilization only happened in the lens. In the current digital era, some cameras perform IS by moving the sensor, rather than a lens element, to compensate for camera motion. This is the approach taken in the Olympus E-520. On an SLR camera, sensor-based IS has the obvious advantage of making essentially all your lenses IS models. What hasn't been clear, though, is whether sensor-based IS can compete with lens-based designs in terms of effectiveness. The argument has been made (primarily by makers of IS-equipped lenses) that a lens-based approach is optimal, because the IS system can be tuned very specifically for each lens. The central notion of this argument is that the sensor-based approach must involve compromises, because it has to accommodate the needs of a range of lenses. Until now, there's been no way to evaluate the validity of such arguments, so all discussions have necessarily been theoretical.

While we can't generalize from one camera's test results to all sensor-based IS systems, the performance of the Olympus E-520's IS system certainly demonstrated that there's no inherent reason why sensor-based IS systems should underperform lens-based ones. Read on for all the details.

Top-Level Summary

The bottom line on the Olympus E-520's IS system is that it turned in a superb performance, very much on par with the best lens-based IS systems we've looked at. Both our "shaky" and "steady" shooters (we'll call them Steady and Shaky respectively from here on out) saw similar amounts of shake reduction with a 50mm lens attached (equivalent to a 100mm lens on a 35mm camera), while Shaky saw more improvement with a 150mm lens (equivalent to a 300mm tele on a 35mm camera).

We understand that these results could raise a bit of discussion. There's a thread on our Message Forums on which we invite you to post your responses.

Olympus E-520, 50mm lens
(Slowest average shutter speeds for motion blur of 0.5)
Tester 1/FL IS Off IS On Improvement
"Steady" 1/100 1/29 1/4 2.7
"Shaky" 1/74 1/11 2.7

Olympus E-520, 150mm lens
(Slowest average shutter speeds for motion blur of 0.5)
Tester 1/FL IS Off IS On Improvement
"Steady" 1/300 1/95 1/22 2.1
"Shaky" 1/234 1/40 2.6

As we've found with essentially all IS systems we've tested to date, results in our real-world tests don't come close to matching the manufacturer's claims. For the E-520, Olympus claims "up to 4 EV steps" of shake reduction, while the most either of our testers saw was 2.7 stops. While we wish the industry would adopt more believable performance claims for IS systems, we by no means single Olympus out in this regard: Our results here are very consistent with our findings for other manufacturers, both in terms of the amount of improvement claimed, and the amount we actually measured.

One difference we did notice with the E-520 vs. lens-based IS systems we've tested is that it achieved greater shake reduction at shorter focal lengths than at longer ones. Most lens-based systems we've tested trend in the other direction, showing more improvement at longer focal lengths.

As noted, both testers saw similar levels of improvement at 50mm. Steady could manage sharp shots unassisted down to about 1/29 second, and an amazing 1/4 second with IS enabled. Shaky could only manage 1/74 second unaided and 1/11 second with IS on, but the relative improvement was the same, an impressive 2.7 stops.

With a longer lens attached, the amount of improvement was less, but still quite good. Steady could get sharp shots with the 150mm lens unassisted down to 1/95 second, and all the way to 1/22 second with IS enabled, for an improvement of 2.1 stops. Shaky could only go to 1/234 second unaided, but managed 1/40 second with IS on, an improvement of 2.6 stops.

Overall, the Olympus E-520 delivered really excellent IS performance, easily on par with the best lens-based systems we've tested to date. It's very interesting that it provided more improvement with the shorter lens attached: At this point, we've only tested this one sensor-based IS system, so we can't draw any general conclusions from it. it's possible that sensor-based systems could run into limitations at very long focal lengths, but in the case of the E-520, its performance with a 150mm lens attached (equivalent to a 300mm lens on a 35mm camera, or a 200mm lens on a DSLR with a 1.5x crop factor) was about as good as that of one of the best lens-based IS systems we've tested, namely that of the Canon 70-200mm F/4L IS. And at shorter focal lengths, it did better.

Going forward, it would be interesting to look at how well a sensor-based IS system handles even longer focal lengths, but for the vast bulk of amateurs, a 300mm equivalent is the longest lens they'll use anyway. This isn't to say that we won't test a longer lens on a sensor-based IS system at some time in the future; the point we're making here is that the question is moot for a large percentage of users.

One notable difference between sensor-based and lens-based IS systems is the impact both have on the viewfinder image: A lens-based IS system will stabilize the image in an optical viewfinder, as well as reduce image blur in the final photos. The same is true of a sensor-based IS system when you're operating with a camera in Live View mode, where the viewfinder image is taken directly from the camera's main image sensor. When using an optical viewfinder, though, a sensor-based IS system doesn't stabilize the viewfinder image at all. As a result, it may feel as though a sensor-based IS system isn't doing as much for you as a lens-based one when you're looking through the viewfinder. In extreme circumstances, this lack of stabilization of the viewfinder image could make it difficult to accurately frame your shot. Our test results of the Olympus E-520 showed pretty conclusively, though, that it delivered stabilization performance in the final images very much on par with the best lens-based systems we've tested.

Performance Graphs

For those wanting a little more detail on how the Olympus E-520 body performed, here are the performance graphs showing our actual test data. (See our article How to Read Image Stabilization Test Results for an explanation of these graphs. Techno-fanatics interested in the gory details of our test methodology should read our Image Stabilization White Paper.)

Click here (for expanded graph, showing all test points and the full range of blur values.


Click here for expanded graph, showing all test points and the full range of blur values.


Click here for expanded graph, showing all test points and the full range of blur values.


Click here for expanded graph, showing all test points and the full range of blur values.


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