What diagonal should I choose, Prism or Mirror type?
In this article, I take the SV188P and SV138 as the example, introduce each kind of diagonal's advantages and shortcomings for the beginners, the 45° is more suitable for the terrestrial， or long focus Schmidt-Cassegrain and Maksutov-Cassegrain telescopes, while it induces the CA, and so favored by today's market...... Read More