One of my favorite things to photograph is the night sky. I am always looking for excuses to escape the city lights and stay up late to take pictures of the stars. I am continually trying to improve my skills but have learned a few things along the way.
Resolution - Print Size Chart The numbers on the chart stand for dots per inch (dpi) they say the human eye does not see much beyond 96 dpi, that should give you a good example of what will work to make a good quality print.
Why I was shooting lens manual focus and why wrong - Makinze Muinzer - Shooting on auto allows the camera to preset a focus. I always keep mine on auto focus, and then change it accordingly to what I actually want in focus