A Florentine instrument-maker known as "the thrush," Francini worked semiprecious stones and "evened out the lights [i.e., the lenses] of spectacles." He was in charge of one of the Grand Duke's workshops. In that capacity, he met Galileo (1564-1642), with whom he collaborated in the construction of lenses for telescopes, achieving substantial fame. He is credited with introducing the vertical optical lathe, a design still in use. Francini continued to make telescopes after Galileo's death, and was also in contact with Evangelista Torricelli (1608-1647). The esteem in which Fortini was held by Grand Duke Ferdinand II de' Medici (1610-1670) and his clients is not the only evidence of his high repute. In a letter to Evangelista Torricelli of 1645, Father Marin Mersenne (1588-1648) mentions the lenses ground in Florence by Francini.