I use a Canon 5D Mark III for Landscape & Night Photography. In order to get pin point sharp stars at night, I've been trying the live view method to zoom in on a bright star and manually focus until it becomes tack sharp. The problem I'm having is that when I zoom in 5x or 10x, I cannot see anything but noise. I've attached a photo to show you what I see. I apologize for the quality as it was snapped in the dark with my iPhone. I've tried with exposure simulation both on and off with no luck. Does anyone else have this same issue and if so, how can I get around it?
Just focus to infinity. You might be focusing on a very dark object.