Howdy. I apologise in advance if this is a dumb question
I had the 'joy' of collimating (with a cheshire EP) my Skywatcher 130mm Newtonian on the weekend and generally speaking, I think it was a success. When viewing a star I get nice concentric diffraction rings on either side of focus. However, I've noticed that when using my 5mm EP (Orion edge-on Planetary) at its 'best' focus on a bright star, I still have diffraction rings visible around the star. Is that normal?? Alex