Damadsetta wrote in post #12451135
Leaving the IS on slows focus speed, so best to turn it off for wildlife, sports etc.
Nope...neither have I.
I wouldn't say it's pretty common knowledge that it slows focus speed - I doubt it has any major effect on focus aside from the millisecond that it takes for the IS to activate.
Katalyst wrote in post #12451266
I don't get this whole 'get rid of the IS while shooting anything fast' issue,
I would suggest that's because you obviously don't understand how IS works, or what its primary object is.
The reason it's suggested that IS is turned off when shooting fast moving or erratically moving objects (race cars, football players etc) or objects is because it's not designed to, and is incapable of stopping movement in the subject.
It is designed to eliminate camera shake caused by the user.
Using higher shutter speeds for sports essentially negates the need for IS.
Katalyst wrote in post #12451266
...I think it's wonderful to have IS to nail the framing of the shot!...
and just how does IS help to "nail the framing of the shot"?
IS can't possibly control how the photo is composed.
Katalyst wrote in post #12451266
...And let's not forget about panning shots, IS is certainly a useful tool when doing that!...
Not necessarily.
Good panning technique is going to help far more than IS.
Later lenses with the two modes of IS may assist when in Mode 2, but almost all the photographers I regularly shoot with IS lense with actually have IS off, and some, myself included (with the 100-400L), actually have them taped so that the switch doesn't get turned on.
My 300/2.8 and 70-200/2.8 are both non IS models. Deliberately purchased because I don't use IS and didn't see the need to pay for a feature I don't use.
I shoot a fair bit of motorsport and don't seem to do too badly with no IS and frequently pan at shutterspeeds as slow as 1/5sec.
The reason being is as I mentioned above - when using high shutter speeds, IS has no effect (or at best, little effect) because the (usually) faster shutter speeds effectively negate the need for image stabilisation - you are not likely to get camera shake.