IS off while mounting lens?

I don't think you're reading what I wrote. I'm not argueing that ignoring the manual and unmounting the lens with AF lock will result in even more lose elements. I understand that when IS is actively on, the elements are then only held in place from an electromatic field, and when you suddenly cut power then they're not in a "home" position. But even if IS isn't active and you leave IS on, that doesn't seem to fully lock them down. Hence why brands will recommend switching it to off before unmounting the lens and shipping them. And also why internet posters aren't imagining things when they say there is more of a rattle if IS is left on. It may not be as drastic as unmounting the lens while IS is active, but it's still not fully locked down (otherwise, why would camera brands recommend switching to off/or photographers observing less rattle with it off?).

davesrose wrote in post #17623784
I don't think you're reading what I wrote. I'm not argueing that ignoring the manual and unmounting the lens with AF lock will result in even more lose elements. I understand that when IS is actively on, the elements are then only held in place from an electromatic field, and when you suddenly cut power then they're not in a "home" position. But even if IS isn't active and you leave IS on, that doesn't seem to fully lock them down. Hence why brands will recommend switching it to off before unmounting the lens and shipping them. And also why internet posters aren't imagining things when they say there is more of a rattle if IS is left on. It may not be as drastic as unmounting the lens while IS is active, but it's still not fully locked down (otherwise, why would camera brands recommend switching to off/or photographers observing less rattle with it off?).

I take it you don't own a 100 L IS, right? Get one in your hands and try taking the lens off before it's settled down. Then we'll talk.

docholliday_sc001 wrote in post #17624162
I take it you don't own a 100 L IS, right? Get one in your hands and try taking the lens off before it's settled down. Then we'll talk.

That's it. You apparently can't read my posts or my signature....

davesrose wrote in post #17624189
That's it. You apparently can't read my posts or my signature....

No, that's the point. Either you don't own the lens, or you should try to actually power up the IS, take the lens off, and experience the clunking yourself. Not the little wiggle that normally exists, but the chunk moving, marble in a jar sound.

davesrose wrote in post #17623784
I don't think you're reading what I wrote. I'm not argueing that ignoring the manual and unmounting the lens with AF lock will result in even more lose elements. I understand that when IS is actively on, the elements are then only held in place from an electromatic field, and when you suddenly cut power then they're not in a "home" position. But even if IS isn't active and you leave IS on, that doesn't seem to fully lock them down. Hence why brands will recommend switching it to off before unmounting the lens and shipping them. And also why internet posters aren't imagining things when they say there is more of a rattle if IS is left on. It may not be as drastic as unmounting the lens while IS is active, but it's still not fully locked down (otherwise, why would camera brands recommend switching to off/or photographers observing less rattle with it off?).

Actually, there is NOWHERE in a Canon manual that says to switch off before dismounting/mounting a lens. There's a reason the lens contacts are designed in the ramped pattern: it's so the ground pins will engage before any signal or B+ pins.

Please try to read this time. I do own the lens, as my signature attests. I can confirm that it does jiggle more if you dismount it if you have kept the IS active. But that's still not relevant to what my point has been. My point has been that the lens elements aren't fully locked down when you keep IS on. That is why camera brands recommend you first switch it to off before dismounting, and why photographers claim that there's less of a rattling noise with it off (irregardless if they've dismounted within the 2 seconds the IS is fully active after AF). Edit: since you're posting just one Canon manual: refer back to the OP who says Sigma is recommending turning the switch off or Choderboy who says Nikon recommends turning the switch off before shipment.

docholliday_sc001 wrote in post #17624202
Actually, there is NOWHERE in a Canon manual that says to switch off before dismounting/mounting a lens.

Which lens? My post, #8, was, "The book for the old 100-400 lens said to not change lenses if the IS was on & active. I don't know what it says about the newer lenses."
artyH's Post #10 confirms that re: the 24-105L IS.

davesrose wrote in post #17624204
Please try to read this time. I do own the lens, as my signature attests. I can confirm that it does jiggle more if you dismount it if you have kept the IS active. But that's still not relevant to what my point has been. My point has been that the lens elements aren't fully locked down when you keep IS on. That is why camera brands recommend you first switch it to off before dismounting, and why photographers claim that there's less of a rattling noise with it off (irregardless if they've dismounted within the 2 seconds the IS is fully active after AF). Edit: since you're posting just one Canon manual: refer back to the OP who says Sigma is recommending turning the switch off or Choderboy who says Nikon recommends turning the switch off before shipment.

"My point has been that the lens elements aren't fully locked down when you keep IS on." Actually, the lens elements are locked down - usually by a retaining ring or cement. It's the IS module that's not locked down. If the *elements* are moving around, you'd have one hell of an astigmatism in the optical path.

"recommends turning the switch off before shipment". Ok, well, turning the switch off before shipping is usually a good idea, unless you want the camera powering up and running down a battery. Stigma can recommend whatever they want, too. Electrical design and properties don't change. Ever wonder why CF slots have longer pins than others? Or why SD cards have certain contacts longer?

PhotosGuy wrote in post #17624211
Which lens? My post, #8, was, "The book for the old 100-400 lens said to not change lenses if the IS was on & active. I don't know what it says about the newer lenses."
artyH's Post #10 confirms that re: the 24-105L IS.

Yes, *on and active*. I was referring to the powering down the camera, as derived from post #31. We are talking about the 100/2.8 L IS lens - where nothing in the camera manual nor the lens manual says to power down, disable the IS, or anything else before dismounting. The only thing it says is to wait ~2 seconds before removing the lens.

"In Nikon and Canon's implementation, it works by using a floating lens element that is moved orthogonally to the optical axis of the lens using electromagnets."

https://en.m.wikipedia​.org/wiki/Image_stabil​ization

The IS module isn't what's floating...the lens elements are.

docholliday_sc001 wrote in post #17624236
The only thing it says is to wait ~2 seconds before removing the lens.

It seems to me that Canon feels that now it would accomplish the same thing?

davesrose wrote in post #17624250
"In Nikon and Canon's implementation, it works by using a floating lens element that is moved orthogonally to the optical axis of the lens using electromagnets."

https://en.m.wikipedia​.org/wiki/Image_stabil​ization

The IS module isn't what's floating...the lens elements are.

You keep believing that...it'll be alright. Glass elements floating around in mid-air. Awesome.

PhotosGuy wrote in post #17624253
It seems to me that Canon feels that now it would accomplish the same thing?

It takes about 2-3 seconds after stopping AF for the lens to grab the IS module (Compensation Optics Lens Barrel) and return it home to the parking position so that the IS module doesn't slosh around.

The IS module is spring loaded, usually at the "parking position". It uses a series of cero-magnetic coils to pull it around the axis. When the power is on, the magnets "grab" the optical module. When power is off, it floats on the springs. The 2 seconds or so is for the module to return to the proper position before the magnetics release it.

davesrose wrote in post #17624297
http://www.tamron-usa.com …od_pg/70200VC_d​iagram.jpg

And you keep being rude and believing the lens element is attached to the IS module!

It is...usually with a set of springs or on a ball bearing set. Ever taken one apart and serviced it? Anyways, ya'll have fun with this. I've got better things to do than try to convince you and your Internet sourced diagrams...like photographing.