Originally posted by guinnessman Sadly, I've only taken out this lens once, still struggling with camera shake at the long end:
Quick tip: safe speed rule of thumb is 1/focal length, accounting for crop, i.e. 1/300s on film at 300mm, at least 1/500s on APS-C.
You could get away with less, depending on the circumstances.
Half-press the shutter button and give time to the SR system to arm and settle (1-2 seconds) - you can also check what happened in the EXIF data as well (SR status will be recorded).