I have been using AV mode on my S-90 and get reasonable pics of non-moving objects (reasonable for me--crap for a good photographer). However on a recent drift dive at Cozumel, I was enjoying the dive so much that I was not thinking that in addition to the fish, I too was moving with reference to the coral even when I was not finning. Result: many blurry photos. Is there a recommended shutter speed setting that I can set up to capture slow moving fish and to offset the drift? Thanks in advance.