In the early 1960s the Beatles posed for hours for the German photographer Astrid Kirchherr, even before the roster of four band members was finalized. She met them when they first played in her native Hamburg and encouraged them to imitate her bowl-cut hair and collarless jackets.

She was briefly engaged to the bass player Stuart Sutcliffe, who died of a brain hemorrhage in 1962, at 21. She later tried to branch out as a photojournalist, but potential clients always asked, “Where are the Beatles pictures?”

This spring Ms. Kirchherr, 73, decided to shed the baggage. Early this fall Guernsey’s auction house in New York will offer about 800 of her negatives and prints. Although she says she has remained friends with the surviving Beatles, she cannot wait to stop being asked about them, and the past in general.

“I must tell you the truth, I’m absolutely fed up with it all,” she said in a recent phone interview. She added, “I’ve got to take care of my age.”

Buyers at the auction will receive rights to reprint and publish the photos “as they see fit,” Arlan Ettinger, president of Guernsey’s, said....