at what shutter speed you turn IS off?

[Canon-F1]

You don't need to shoot a single image ever to have a very in depth knowledge of how the technology actually works. Personally, with regards a technical question relating to Canon gear, I would go with the word of the real Chuck over Jay Paredes.

LOL

chuck westfall will also tell you the 6D has a great autofocus system.   

[Canon-F1]

He might be in PR, but he doesn't give a damn when you use IS on a lens you already own, if his comments were a stinging sales brochure for lens based IS over body based IS then you might have a point, but nothing he says in this instance has any effect on sales, indeed he wants people to be very happy with the lenses they own, get the best out of them, and tell everybody else the best way to get keepers. Happy knowledgeable customers are the most effective sales tool.

a good PR man is always on the job.
IS lenses cost more so he has to promote them in every possible way, always.

[Canon-F1]

Common sense tells us it does, but not necessarily in every conceivable situation.

does it?

IS needs processing power.
my common sense is not sure what is correct.... could be either.

[TrumpetPower!]

IS needs processing power.

That processing is done entirely by the lens, not by the camera. That's why IS works the same on any EF mount body, from film through the 1DX. It's also why upgrading bodies doesn't enable new IS modes and better IS performance on old lenses.

So, yeah. I would entirely expect IS to improve autofocus performance. And I'd be astounded if IS degraded AF performance, though I could easily imagine situations where whatever improvement it might make would be negligible.

Cheers,

b&

[pwp]

Chuck Westfall

well... how many photos does the guy shoot a year?
i have read so much crap from him (and i mean the real chuck not the fake one) 

Not only is Chuck Westfall a very good friend to the Canon community globally, he does stay ahead of the game in terms of what works and what doesn't. And then he has a great ability and willingness to communicate. And it goes back a long way. He was an awesome contributor to the now gone and much lamented Rob Galbraith forums. His prompt technical posts played a significant role in helping a lot of photographers around the planet make the transition from film to digital. And he hasn't stopped giving.

Quite likely he doesn't shoot as much per year as you do, but to flame this guy is a travesty.

-PW

[Botts]

You don't need to shoot a single image ever to have a very in depth knowledge of how the technology actually works. Personally, with regards a technical question relating to Canon gear, I would go with the word of the real Chuck over Jay Paredes.

LOL

chuck westfall will also tell you the 6D has a great autofocus system.   

It depends on use case.  If you're not shooting action, the 6D does have great autofocus, it's quite accurate, and works in extremely low light.  If you are shooting sports though, you wouldn't call it great.  I'd take slightly less accurate AF for speed every time for sports.I would say though, for me, I'll use IS all the time, unless I'm on a tripod.  I rarely shoot at 1/1000s as I'm usually more concerned about deep DOF. That said, I'm shooting animals on Tuesday, I'll have to test my AF speed with the 70-200 f/2.8 II and the 70-300L with IS on and IS off, to see if it's a notable difference.

[RMC33]

He might be in PR, but he doesn't give a damn when you use IS on a lens you already own, if his comments were a stinging sales brochure for lens based IS over body based IS then you might have a point, but nothing he says in this instance has any effect on sales, indeed he wants people to be very happy with the lenses they own, get the best out of them, and tell everybody else the best way to get keepers. Happy knowledgeable customers are the most effective sales tool.

a good PR man is always on the job.
IS lenses cost more so he has to promote them in every possible way, always.

He was talking about a lens the owner already had, there was no potential sale involved. Indeed few lenses in the Canon range have IS or no IS options, obviously the 70-200 f2.8 and f4 (but wasn't the non IS 2.8 dropped?) and when there is that option IS is not the only difference in the lenses, a laå 100mm macro with weather sealing and internal focusing.

The Non IS is a 1995 lens and has been discontinued recently. I was told that by CPS while on the phone the other day. I still see a lot of them on my local CL though.