Thanks Peripateic and John G for your input,
as for fencing I'll try using the ISO 1600 and more manual settings
most of the time was under sport settings.
and play around with the settings with my current lens this few weeks to find out the range of lens n if i should get with larger aperture.
JohnG, thanks for the info on the distance on the 300mm zoom.
but yea, I guess I'll leave those fast close up photos to the professionals for now.
and when you mention exposure time being slow what is the exposure time needed for sport event?