I am not sure that the focal length rule works anyway on long lenses. I can handhold my 400/5.6 at, say, 1/500 and get sharp shots most times but if I add a 1.4tc bringing it up to 560mm I struggle to get sharp shots at 1/1000 or even faster (when using a tc I always use a tripod which gives me good results).
I have a theory that the focal length=shutter speed rule works on short focal lengths (say 100mm or less) but as you go up the focal length it becomes less effective. Of course IS comes into it as well.
I do not know if you should add the crop factor or not but to be on the safe side it is worth while to add it.
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