IS reaction time - is IS fast enough?

Started Nov 15, 2012 | Discussions thread
amd Regular Member • Posts: 349
Re: IS reaction time - is IS fast enough?

photostarts wrote:

Earlier this week a salesman in Jessops gave me the "hard sell" in trying to persuade me to buy the non-IS version of the 70-200mm f/4L lens. I guess he thought I'd find the price attractive, as the version with IS costs a whole lot more.
"But it gives you up to 4 extra stops," I pointed out.
"In what way?" he replied. "It's still f/4, so you won't get any benefit."
I explained that having IS meant you could stop down or use a slower shutter speed.
"No, no," he said, "By the time the IS has done its job, you'll have missed the shot."

Don't know which body you are using, however on my 5D MK II the AF so far never outperformed the IS on my 70-300L or 100L (using center point only). Also think that he has the wrong idea of how the IS/AF combo works. Don't believe it makes sense to think of the combo as: "IS waiting for gyro sensor, moving lens element(s), and then AF waiting for IS to complete to engage" ... These two systems should be working in a mostly decoupled way. The AF should be focusing, and in parallel the IS tries to detect and handle motion blur.
I am assuming that IS is using a different part of the lens system than the AF (which makes a lot of sense to me)

My conclusion was, that it is hard to proof that there is zero side effect on AF speed, but they should not be ´╗┐directly´╗┐ related.
Apart from this, the sales dude desperately needs some "value selling" training. You may have come back when the IS version was on stock again, if he would have had engaged in a valuable  dialog ...
My two cent's

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