Very hard to find, from the noted high-end Maksutov maker. The Maksutov-Gregorian design uses a convex instead of concave mensicus corrector so the spot secondary mirror gives an erect image straight thru with no diagonal needed. The ultimate terrestrial scope, can be used with a diagonal for astronomical.
Gives excellent star test, primary mirror focusing with coaxial thumbwheel around the ocular tube. Small secondary obstruction of 28% gives better contrast than typical catadioptrics. Comes with an interferogram and test report:
.035 waves RMS
.216 waves peak to valley.
In excellent condition, recently collimated by TEC. Comes with mounting rail, caps and removable red-dot finder. Best offer over $500. Looking for an FS-102. No photo.