Switching IS off before taking lenses on/off the body?

[cls]

Hi, i just saw the latest "lens accessories" video in the EF101 video series. The one thing in it that I haven't heard before was a general tip towards the end (around 4:35) of the video: For IS lenses, one should turn IS off before taking the lens on/off the camera body. I have managed to stay completely unaware of this until now, and I'm not sure why one should do this. Could anyone explain the reason why one should set the IS switch to OFF before removing a lens?

[peety3]

Inside the lens, there's a set of elements that are purposefully not anchored to the lens body (they're on pivots, and connected to a servo). There's probably a desired position for those motors if they aren't powered, to minimize damage and/or ensure proper startup on the next use.

My wife's 100/2.8 IS Macro L rattles a lot more if I take it off the camera immediately after use versus if I let the IS system finish its wind-down.

[Sean Setters]

You should never disengage the lens while the IS is still running. Turning IS off ensures you don't do this.

You might think to yourself, "What does it matter? I'm never taking a picture when I'm taking the lens off." However, I can't tell you how many times I've laid my camera down on the shutter button of the battery grip while taking off a lens. :-/

[sedwards]

does that mean you guys take lenses off without turning off the camera ?

[Sean Setters]

I have on my occasions, by accident. It's those times when having IS engaged is a bad thing.

[Black_Dog]

I am now in the habit of turning off the camera anytime I mount or remove a lens, flash or memory card. I think the latter is unnecessary because the camera turns itself off when the memory card door is opened, but I do it anyway… because it’s a habit.

I haven’t always done this and the worst I’ve ever experienced from leaving the camera on through any of these changes is a Speedlite inadvertently firing (if it is also on). Likewise, I have never has a USB flash drive go bad if I’ve removed it without unbooting it properly from my computer. But I know people who have fried their flash drives by doing so. Better safe than sorry with any kind of electronics like this.

[peety3]

I do lots of lens changes with the camera still on, though I do make sure I've waited until two seconds after the memory card finishes its write cycle.

With respect to Sean's comment, I normally grab the left side of the camera with my left hand, and press the right side of the camera into my big/soft/squishy belly, then grab the lens with my right hand in such a way that I can push the lens release button with my pointer finger. I'm really digging the LowePro LensExchange 200 AW cases as they do a nice job of holding lenses through a swap.

[cls]

Thanks for your thoughts on this. Maybe there's som technical "secret" in the lens internals that prefers IS to be off when detaching the lens, or maybe it's as simple as eliminating the risk of IS actually being activated when removing it. Both theories seem reasonable. (I suppose I'll keep on switching lenses as I always have though: With the camera OFF, but with the IS switch still set to ON.)

[neuroanatomist]

I suppose I'll keep on switching lenses as I always have though: With the camera OFF, but with the IS switch still set to ON.

That's how I do it...

[Kayaker72]

+1. What I've read before is that IS moves to a locked position when off. But I do not believe that is just the switch being in the "IS Off" position. The real goal is to not have IS active when you dismount your lens. As mentioned above if not, my understanding is that the IS group may be loose. But IS not being active is also accomplished by turning your camera off or not pressing the focus button for a couple of seconds.