Im assuming you mean even after fine focusing your image is still fuzzy?, there are several possible problems, for one thing a name like antares/orion/vixen is no guarantee you have good optics, optics are good only when a good optician, or atm/astronomer with experience says it is.
As for collimation, as long as it isnt too much out of alignment you shouldnt have fuzzy images at high mag.
try a ronchi grating this will give you a basic
idea of the optical quality.