Will Crutchfield sat in front of an orchestra on Monday, correcting the details in Bellini’s “Il Pirata.” “The subsequent bars are sounding the same as the first,” he told the players, from the Orchestra of St. Luke’s. “The subsequent ones should be ghosts.”

“All of it crisper, shorter, lighter,” he added a few minutes later. He warned that a 32nd-note pickup — about as quick a gesture as there is in music — was “getting swallowed.”

Mr. Crutchfield has been delving into these kinds of details now for decades: “Il Pirata,” which will be performed on Saturday evening with Angela Meade and Santiago Ballerini, honors the 20th anniversary of Bel Canto at Caramoor, the opera-in-concert series he has led to regular acclaim at the Caramoor Festival in Westchester County. The series, featuring carefully selected casts of rising artists, has unearthed rarities by Rossini, Donizetti and composers in their early-19th-century circle.

If 2017 is a milestone year for the series, it is also a farewell. Next summer Mr. Crutchfield and his bel canto operation will decamp for Purchase College, part of the State University of New York, where it will be reinvented as Teatro Nuovo. This is, both parties report, a mutual decision that will give Mr. Crutchfield more freedom and Caramoor more programming leeway.