100-400 focus issues?

I just noticed something weird on my 100-400. When IS is on and I "back button" focus (or use the main buton in full auto mode) the image in the viewfinder shifts and moves again when the button is released. When IS is switched off it doesn't happen. BTW this doesn't happen with my Canon 70-200 2.8 IS. Both lenses were mounted on a tripod and I'm using a 7d.
Anybody else experience this? Any clues to the fix? Do I need to send it in to Canon?

The IS can be a little jerky when engaging/disengaging on my 100-400. It doesn't seem to affect anything.

Two points.

1, IS will jerk a little as it activates and deactivates on the 100-400L, that is normal (although using BBF shouldn't activate it, I don't think, only the shutter button but I don't use a 7D and don't know what you can assign to what).

2, The 100-400L can't sense a tripod and using IS whilst mounted on one can cause issues with the IS going into a "feedback" loop as it tries to detect motion. Always turn the IS off on a tripod with this lens, it could be the IS getting jittery with the tripod that is causing what you are seeing.

sandpiper wrote in post #14446416
Two points.

1, IS will jerk a little as it activates and deactivates on the 100-400L, that is normal (although using BBF shouldn't activate it, I don't think, only the shutter button but I don't use a 7D and don't know what you can assign to what).

I have a 5D and BBF activates IS on all my lenses.

I have a 7D, permanent BBF and BBF activates IS on all my lenses. I get the shift occasionally on the 100-400 but just put it down to a well used lens. I don't worry about it.

They recommend you turn off IS on the 100-400 when on a tripod

100-400mm is Canons oldest IS lens still sold.
With Gen 1 IS,. it is very noticeable in the viewfinder when it engages or stops.

As others have stated, Gen 1 IS lenses should have IS turned off when mounted on tripod.
Leave it on for a monopod ... as usually we aren't as stable with a monopod as we are with a tripod.

FYI, the 70-200mm IS has 2nd Gen IS, which when mounted on a tripod detects it, and drops into a tripod mode. Very helpful when shooting with a long lens and a tripod, not so much on the 70-200mm, but there anyway.


Jake - who feels the 100-400mm is a lens designed to be hand held from the beginning to end!

More elaborate info on Canon IS can be found here;

https://photography-on-the.net …d.php?t=86975#p​ost1066324

Maybe my old eye's but I've been seeing similer things with the when the IS kicks in.

Like its not focused just right so I'll release and quickly depress the button half way before the IS turns off for a quick re focus or two sometimes.

I'm probably starting a bad habit. I know I need to be wearing glasses anyway.