Five centuries before the Nazis murdered, displaced and exiled millions of European Jews, the Jews of Spain were tormented and dispersed with ruthless brutality.

Sephardic Jews living in various countries subsequently struggled to maintain their religion, language, rituals and artifacts — often in secret. What is the state of Ladino culture all these years later? A trio of vastly different movies screening in the S.F. Jewish Film Festival provide some unexpected answers.

At the core of “The Longing: The Forgotten Jews of South America,” easily the most important of the three, is the determination of a handful of Ecuadorian and Colombian men and women to convert to Judaism. Filmmaker Gabriela Bohm takes her time laying out the historical context, and curiously gives no hint that their story is going to become a wrenching nail-biter.

Most of them believe they are descended from Ladino Jews, but their communities (where there is one) don’t recognize them as Jews because their mothers aren’t Jewish. So they are truly Jews by choice, jumping through a series of hoops that will astound and inspire the typical American Jew who takes his identity and faith for granted.

The hurdles include a 31-hour bus trip each way from Colombia to Guayaquil, Ecuador, where they will take the final steps with a Kansas City-based, Brazilian-American, reform rabbi. One might expect the local Jewish community to embrace anyone who wants to adopt the faith, but not so.

The documentary develops a fascinating, low-key tension between two competing impulses. The rabbi from America displays a marvelous sense of social justice (although his process is always religious-based), while the board of the Guayaquil synagogue — many of whom are Ashkenazi and consider themselves observant — pushes back, treating the newcomers as second-class Jews.

“The Longing” provides ample grist for a reasoned post-show “Who is a Jew?” discussion, but it’s a deeply emotional viewing experience. It’s impossible not to root with all one’s heart for the would-be converts, once the film finally gets its hooks in us. As the rabbi comments, after a Colombian girl’s oral exam, “There are no 12-year-old girls in Kansas City that express themselves like this” about their Judaism.

“The Longing,” which is co-presented by Congregation Rodef Sholom, will move any viewer but it’s especially recommended for social action-oriented spiritual and community leaders looking for a shot of inspiration.

Compared to the South American converts, the passionate 30-something Israeli singer Yasmin Levy grapples with a seemingly more trivial dilemma. Should she continue to perform the traditional Ladino tunes savored and favored by an aging and shrinking population, or follow her muse (and expand her audience) by melding Ladino with flamenco?

The one-hour doc “Ladino — 500 Years Young,” is part of a three-part Israeli TV series about people who “revive” fading culture. Levy’s father, Yitzhak, was both a beloved Ladino singer and a collector and informal archivist of songs and performances (a Sephardic Alan Lomax). He died when she was an infant; it was only when she began singing as a teenager, and then steeped herself in his tunes, that she

developed a meaningful relationship with him. (The film alternates her songs and his on the soundtrack in an attempt to erase the distinction between the past and the present, the historical and the living.)

So Yasmin frets that her development as an artist means giving up her role as “curator” of her father’s legacy and keeper of the flame. Everyone in her life, from her mother to her husband/manager to a banker whose hobby is collecting and singing old Sephardic melodies, has an opinion.

There’s apparently no one else to carry on the Ladino tradition, so Yasmin feels responsibility and pressure. She wants to do the right thing, but she also knows that it’s no good to anyone if she’s not true to herself.

“Ladino,” co-presented by Jews Indigenous to the Middle East & North Africa (JIMENA) and the Bureau of Jewish Education’s Jewish Community Library, is the quintessential SFJFF film in that it confirms the universality and familiarity of the Jewish experience, regardless of culture, language and geography.

The same could be said of “My Mexican Shiva,” an enjoyable and bittersweet sliver of fiction set in motion by the sudden death of a ribald Mexico City Jew. Gracefully directed by Alejandro Springall, its amusing conceit is that the information that comes out about the deceased during the week of shiva will be used by the angels of light and darkness to determine the fate of his soul.

The extended family gathers and (in keeping with the conventions of the genre) old grudges, romances, jealousies and insecurities sprout anew. The film doesn’t develop any of the characters sufficiently for us to have an emotional connection, but it’s sensible and tasteful enough not to stoop to crude or farcical plot twists (well, no more than one or two).

“My Mexican Shiva,” which is co-presented by Jewish Family and Children’s Services and Congregation Sherith Israel, evokes a well-defined community of Mexico City Jews who are free to assimilate, and yet find comfort in their rituals and traditions on major occasions.

In that sense, they are closer in spirit to many American Jews than to their Ladino forebears.

“The Longing: The Forgotten Jews of South America” screens at 4:30 p.m. Mon., July 30 at the Aquarius in Palo Alto, 4:45 p.m. Sat., Aug. 4 at the Roda Theatre in Berkeley and 2:15 p.m. Sun., Aug. 5 at the Rafael Film Center in San Rafael. Tickets: (925) 275-9490 or www.sfjff.org.

“Ladino — 500 Years Young” screens at 2 p.m. Wed., July 25 at the Castro Theatre, 2:15 p.m. Mon., July 30 at the Roda and 2:30 p.m. Wed., Aug 1 at the Aquarius.

“My Mexican Shiva” screens at 6:45 p.m. Mon., July 23 at the Castro Theatre and 7 p.m. Sat., July 28 at the Aquarius.