Why do some directors keep hiring the same editor film after film? It’s all about chemistry — and being on the same esthetic wavelength.

This season’s awards-worthy entries include the pictures of two veteran helmers who have worked with the same cutters during the latter parts of their careers.

Joel Cox, who cut Clint Eastwood’s “Changeling” and “Gran Torino,” has edited most of the director’s films since 1977’s “The Gauntlet.” Alisa Lepselter, editor of “Vicky Cristina Barcelona,” has edited every Woody Allen picture since “Sweet and Lowdown” in 1999.

Personality plays a key role in Lepselter’s relationship with Allen. “I’m pretty diplomatic, and I didn’t come in there to challenge him,” she says. “It took him awhile to trust me. He had worked with (editor) Susan Morse for many years and I’m sure they finished each other’s sentences.

“When I came in out of the blue, I think there was some resistance at first,” Lepselter adds. “(But) I have learned what he likes, and how we work together has evolved over the years as he got to know me and trust me. He’s now more open.”

After decades of collaboration, Cox and Eastwood have also reached an easy working rapport. “There was a bit of turmoil at the beginning … and he watched me like a hawk,” Cox recalls. “(But over time) our relationship came together because he saw in me things I could do that others hadn’t done. He said, ‘I don’t know what your plans are, but I would like to have you on all of my films.’ I said, ‘Well, I’m here.’ ”

Yet there are still unexpected moments. “By now I pretty much know where he’s going with it, but he still surprises me,” Cox says. “He once told me, ‘Don’t second-guess (anything). I don’t do that as a director. I want to see what your first instincts are … because I trust what you are doing.'”

Coincidentally, Cox and Lepselter both faced similar linguistic issues on their latest films. Some of the dialogue in “Vicky Cristina Barcelona” is in Spanish, and “I was skeptical about the language at first,” says Lepselter. “Neither Woody nor I speak Spanish, so I thought at first it would be difficult, but it turned out to be not a problem.”

“‘Gran Torino’ has Hmong people in it speaking their language,” Cox says. “It’s amazing to edit a film and not understand one word they’re saying. Clint said, ‘When you listen to them, you get the rhythm of it.’ We got the rhythm.”