Posted By Marcin Klapczynski
I am new in the field and I just have started gathering materials and reading about ATM.
Although vast majority of people say that a parabolic mirror is necessary for good quality pictures in newtonian telescope (no spherical abberation), I found some suggestions about grinding a spherical mirror. They say that making proper parabolic shape is "extremely difficult to even an experienced mirror maker". Moreover they argue that they have never seen blurred picture using spherical mirror...
But then you have to follow Maksutov equation (lamda/4) and 8'' mirror (that I am planning to make) would have to have focal length = 72 inches. That would make focal ratio f/9 ! It is kind of awkward... :S (or it isn't?)
So my question is: is it really so hard to make perfect parabolic 8'' mirror for a guy with lots of patience and excellent manual skills like me? 8)
Thanks for any advice!