What a blast for those who make the MFA’s single screening (this Friday, June 28, at 8 p.m.) of Leah Mahan’s joyous Sweet Old Song. It’s a documentary hymn to 91-year-old folk-and-blues musician Howard "Louie Blue" Armstrong, and to his soul-stirring December romance with Boston’s Barbara Ward, his percussionist, girlfriend, and, now, wife. The film delights in their courtship, in how Ward was won over by a man 30 years older, as much by his drawings and his Cyrano letters as by his tremendous music.

It’s a no-brainer to predict that when lovebirds Howard and Barbara march out to play after the sweet film, there will be a momentous standing ovation. Be there when Armstrong, with a repertoire as wide as Mississippi John Hurt, chooses among 22 instruments! Will it be mandolin, fiddle, or guitar to go with Ward’s tambourine and pristine harmonies?

If you can’t make it this Friday, don’t despair: Sweet Old Song will arrive on August 5 on WGBX as part of PBS’s P.O.V. Call me a Bay State patriot: the 2002 P.O.V. episodes that move me the deepest were made locally: Sweet Old Song (cut with panache by Boston’s all-star editor, Bill Anderson) and, on August 12, Mai’s America, a compelling look at a Vietnamese teenager’s year in the USA that was made by Framingham’s Marlo Poras.

Not that there’s a lot of competition. It used to be that P.O.V. would offer a powerhouse summer anthology of nonfiction films. But this is its 15th TV season, and the series has become safe and a wee bit lazy, the selections chosen with little feel for film form or with any understanding of what makes a documentary "personal." The directors could be interchangeable for half these movies, their work (usually cheapo DV) is so faceless.

Take The Smith Family (July 1). Who can get annoyed at a movie about AIDS victims, especially when they’re as decent as the Salt Lake City–based Smiths? Well, I can when it’s a film made this indifferently and generically, and when there’s a flood of cloying, sentimental piano behind the umpteen hugs and kisses of this goody-goody Mormon clan. It feels like a basement church supper! For the record: straitlaced hubby Steve Smith was cruising on the side and brought HIV into his all-American home, infecting his wife, Kim. The documentary shows Steve’s declining days and Kim’s grit in nursing her failing husband. I could imagine a touching feature article in a newspaper, but where’s the cinema?

Ditto for Boomtown (July 8), a stretch of a documentary about how Washington State’s Suquamish Nation build shacks on their reservation to stock fireworks and make a heap of money selling them to white people for July 4. This is a sketch rather than a movie. Do-gooding filmmaker Bryan Gunnar Cole decides not to show how entrepreneurs pushing almost exactly the same wares duke it out for profits on Independence Day. That might depict some Native Americans as greedy, venal capitalists. Instead, this PC whitewash stereotypes Indians as kindly storytellers obsessed with treaty rights.

Hybrid (July 15) is Monteith McCollum’s homage to his stentorian-voiced grandpa, a man who was obsessed about making Iowa corn sweeter via genetic engineering. It’s the only P.O.V. documentary this year that’s even vaguely experimental: the filmmaker gives formal consideration to his footage, manipulating it to thematic and æsthetic ends. An excellent film, enlightening and entertaining despite its esoteric subject.

Refrigerator Mothers (July 22) is again ordinary, functional filmmaking, though the topic demands some history and allows for some bite. Directed by David E. Simpson, J.J. Hanley, and Gordon Quinn, this is the tale of autism in the 1950s and 1960s, before the cause was known to be a neurological disorder. Back then, autism was regarded as a psychological problem, in which a child was desperately retreating from a withholding "refrigerator mom." The leading Freudian theorist on autism was Bruno Bettelheim, who equated the treatment of the child by his mom with that of a Jew by a Nazi Kapo. Bettelheim is the villain of this documentary: he’s shown delivering his specious theories while grandstanding on The Dick Cavett Show, and we meet many nice, caring mothers who are heroically patient with their autistic children.

Fenceline: A Company Town Divided (July 29) is a documentary from Slawomir Grünberg and Jane Greenberg that starts as a familiar story about how a chemical plant is ruining people’s health before becoming, slowly, a gripping tale about how differently blacks and whites can view life in America. The whites of Norco, Louisiana, adore the local Shell Refinery, where they all have worked. The blacks see Shell as a cause of asthma, cancer, and death, and as a place that has denied them employment.