How good is OS really. I took 4 shots this morning - just 4 - no best of 2 or 3. I tried to be more careful with the two shots at 1/13 sec as they were a stop slower. It paid off with OS ON and didn't help with OS OFF. The slower shot at 1/13 sec (with OS ON) actually came out a little better than the faster shot (1/25). Crops at 100%.