What’s most important to understand about “Amazing Grace” is that, in spite of capturing soul singer Aretha Franklin’s two-night recording of her gospel album before a live audience at the New Temple Missionary Baptist Church in Los Angeles in 1972, it’s not so much a concert film as a time capsule.

The film opens with title cards reminding us of how many albums and hit singles Franklin had already recorded by that time, which were enough that Warner Bros. considered it worth their time to send no less than Academy Award-winning director Sydney Pollack to record both nights of Franklin’s concert for posterity, in addition to the audio recordings that were being made for her “Amazing Grace” album.

One reason is that this concert was seen as the Queen of Soul returning to her gospel roots, with a guest appearance by her father, the Rev. C.L. Franklin, to help drive home the point for those who may possibly have missed it.

But in retrospect, what Pollack and Warner Bros. seemed to recognize was that they were preserving a moment of zeitgeist, one notable enough to draw the Rolling Stones’ Mick Jagger as an unobtrusive member of the church’s audience.

One could charitably ascribe the film’s lack of visual panache to an intentional choice on Pollack’s part for that reason, except that the decades-long quest to resynchronize its images and sound would indicate instead that Pollack was simply trying to film the proceedings however he could, in spite of the plague of “technical difficulties” laughingly identified by the Rev. James Cleveland, as he and the Southern California Community joined Franklin in song.

Backstage preparatory shots are an obligatory feature of most concert films, but what sets “Amazing Grace” apart is that, out of 20 hours of raw footage to choose from, director Alan Elliott chose to keep moments such as the false start of one song, and the request for a glass of water between songs.

As Cleveland told the audience, this was first and foremost a church service, which means you can see Pollack in the background, gesturing to his camera operators and silently mouthing the words SHOOT THEM as he pointed to the audience, because at a gospel concert, the churchgoing crowd is fully half the show.

And the reactions on display are almost as affecting as the music, with men shedding tears and older women collapsing onto the floor, as they’re overcome by the spirit of the proceedings.

With parishioners being moved by the holy spirit at a service, this already makes sense, but with Aretha Franklin in her prime being the one to lead everyone else in belting out those tunes, it’s the least you would expect.

Director John Landis has noted that part of what made it so difficult to record Franklin’s musical scenes in 1980’s “The Blues Brothers” is that Franklin never sings a song the same way twice, and her penchant for embellishment is on display here when it takes her no less than 34 seconds to sing the first two words in the song “Amazing Grace” itself.

What’s striking is what Franklin’s performance reveals about the relationship between her and her father, who was no stranger to hearing her sing, but who constantly flashes grins of amazement, and shakes his head in surprise over how his daughter is able to add her own unique spin to any song.

At the same time, more than anyone else there, he appears to understand the toll that such performances take on her, at one point even taking a towel to dab gently at the sheen of perspiration covering her face, all while she’s still singing and playing the piano.

For as much as concert films style themselves as rock documentaries, few moments are as authentic as the shots of Aretha Franklin between songs, her smile faded, her face pensive, shoulders slumping briefly as she relaxes, before steeling herself up again for the next set.

In those moments, the veteran singer resembles nothing so much as a prize-fighter captured between rounds, readying herself to give it her all again.