In a recent discussion with a fellow photographer about BBF, he asked me if I knew how BBF affected IS, if at all. I wasn't sure, so I thought I would post the question here. Does BBF have any affect on how IS works?. Basically, there are two ways to focus a lens on a DSLR and that is through shutter button focusing or BBF. The question becomes whether or not the lens knows how it was focused, as my understanding is that IS kicks in once the lens has obtained focus. IS then attempts to keep the subject in focus by correcting for any minor movements of the lens. He was concerned that changing the focus of his camera and lens from shutter button focus to BBF would change the way that IS worked. My contention is that this would not change the way IS worked because the lens doesn't know how it was focused, only that it was focused and once it is focused then IS attempts to maintain that focus. So I am looking for an answer to that question from someone who is more knowledgeable on the subject than I am. Any insight that anyone would care to contribute will be greatly appreciated. Thanks.