Astrophotographically optimized lens telescopes (astrographs) consist either of primary optics, combined with a flattener or reducer, or of multi-part (4 to 6 lens) optical designs that enable optimal geometric and chromatic correction. The focal ratio is very short (mostly f / 3.5 - f / 5.6), which shortens the exposure times.
The largest apo from Teleskop-Service is the inexpensive entry into the world of really big refractors. Such a telescope offers joy for a lifetime and is an attraction in every observatory.
From the beginning, the goal was to create the best possible design for an affordable, small, lightweight, and fast Apochromatic refactor for astrophotography.