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<p>Is this really such a big deal</p>
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<p>IMO yes. Assuming this is the Oly 5 axis system then this is a case of the world's best sensors meeting the world's best IS system. Having used both Canon, Fuji and Oly systems the Olympus IS is in a different league. As Steve Huff said, you haven't experienced IS until you have tried the Olympus 5 axis system.<br>
It will work with old lenses too by just keying in the focal length. I've used it with old zooms, where I just keyed the mid point of the zoom range and it works well.<br>
While Canon and Nikon claim 4 stops, if you have old lenses you are going to have to upgrade to get it. With IBIS you get the latest generation of IS every time you upgrade your body.<br>
Putting it another way, I have a choice of upgrading my 17-40L to the new 16-35 f4L, 100 macro to the 100 L and with my 24-105L I am stuck until Canon decides to upgrade the IS unit. With my 40 f2.8 stm I am out of luck. Or I could by the A7II and get IS for all these lenses in one go!<br>
Putting it another way my Canon FD collection just got the latest most advanced IS in the world! I'm stoked. </p>