With Canon's IS system, the big IS lenses (300 F2.8, 400 F2.8, 500 F4 and 600 F4) that are not really going to be used without a tripod or monopod have an IS mode that is designed to counter the small amplitude high-frequency vibrations that are found on a tripod, rather than the bigger amplitude, lower frequency of hand-holding. Do Nikon not do a similar thing?