TPO UltraWide 180mm f/4.5 has the same design as ASKAR FMA180, so below applies to the TPO lens.
ASKAR FMA180 is a Triplet air-spaced APO refractor, which includes two pieces of ED (extra-low dispersion) glass, providing excellent correction of chromatic aberration. The high-quality optics producing a flatter image with striking clarity, and it is tested to ensure that high standards for astrophotography and observation.
Focusing can be quite time consuming process even with the Bahtinov mask (especially with narrowband filters). Additionally, focus can shift with temperature change during the night. We have solved this for you with our special rails mounted autofocuser kit, which can compensate for the front movement of the lens during focusing.
The autofocusing motor rests on the special trolley, connected to the rails. This keeps autofocuser pulley in line with lens focusing ring and enables a balanced, compact solution.