I tried to take pictures of a hummingbird that frequented the feeder outside of my apartment back int he day. I had an Olympus SLR that could shoot at 1/1000th of a second. I took about a dozen shots, on a tripod, and was dissapointed to find the hummingbird was blurred in all of them. It reacted so quick to the sound of the, admittedly loud, shutter that it blurred int he frame. When I lined it up in the eyepiece I snapped the picture and the hummingbird would have changed location by a couple inches when the mirror dropped down again! A quieter shutter, a faster speed, or, as you did, repose; is the only way to go!