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RF 100-400mm F5.6-8 IS USM Free Floating when Vertical


I am new to photography and have recently purchased this lens. My question is when i have the casing held vertical, with little movement the lens inside seems to be free floating. When i turn the casing horizontal again the lens seems to line up perfectly. Should i be worried it was damaged in shipping or is this a normal feature because of the stabilization feature of the lens. Also, i have shot pics on this lens and everything seems fine. Thanks in advance,John


Hello, John.

Our RF 100-400mm rattles a bit when not attached to the camera and held vertically (pointed at the ceiling) and is fairly quiet when held horizontally. That is the "In Lens Image Stabilization" (IS or ILS). Image stabilization is achieved by a floating element controlled electronically by a microchip and electro-magnets, IIRC. Obviously, this is a simplistic explanation and it is a bit more complicated than that, but that is it in a nutshell and what you hear "floating" around in the lens. You can also hear the "In Body Image Stabilizer" (IBIS), which is a little more complicated, but works basically the same. Google "IBIS or IS diagrams" to get a better picture of what is going on in your system. It's pretty cool.

IS Unit in Lens.IS Unit in Lens.

Without actually hearing what you are, it's hard to say if everything is OK, but we have had ours for a couple of years now and it works perfectly with it's occasional rattles and noises.

On a side note, I have read that it is best to "park" the IS by turning it off a few seconds before shutting off the camera. I do this, but often forget. Doing this may extend the functionality of your lens.



Yup. The bits floating around are the image stabilisation group of elements. When IS is functioning (with the camera turned on, take up the first pressure on the shutter button) these elements snap into position and don't wobble. But when the IS is not functioning (turn the camera off, for instance) they are free to float around on their spring mounting. It's disconcerting to hear, and if you peer into the front of many of Canon's lenses you can see them wobbling around. But perfectly normal and not a fault.

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