Jessica Chandler says as a foster youth, she used to hate social workers...until she became one. (Courtsey HBO)

Documentary filmmakers Deborah Oppenheimer and Mark Jonathan Harris said they spoke to a couple hundred social workers while doing research for their new HBO documentary, "Foster."

Most of them would immediately start crying when they came in for their interviews.

"They told us that they don't tell their friends, tell their families that they work for the Department of Children and Family Services," Oppenheimer told KPCC's Take Two. "They turn their badges around when they walk into public places [like] a restaurant."

A lot of social workers feel that the public perception of anyone who works in foster care generally skews negative, in part because the system only gets public attention when something goes wrong, the filmmakers said.

"One of the reasons we wanted to make this movie was because we do feel like the public gets their information at the time of a fatality or at the time of a crisis. And the consequence of that is that people turn away in despair," said Oppenheimer, who produced the film. "The magnitude of it seems so enormous, that they throw up their hands and they think they don't know what to do."

The Child Protective hotline takes calls inside the Los Angeles County Department of Children and Family Services. (Courtesy HBO)

The filmmakers specifically chose the Los Angeles County Department of Children and Family Services because it's the largest child welfare agency in the country, representing nearly 30,000 kids and covering more than 4,000 square miles. DCFS is also an agency that has made headlines for dramatic failures in its mission to protect the most vulnerable members of the community. In a horrific case from 2014, 8-year-old Gabriel Fernandez of Palmdale died following prolonged torture and abuse at the hands of his mother and her boyfriend. Four social workers involved in that case were charged with child abuse and falsifying public records. In a similar case last year, 10-year-old Anthony Avalos of Lancaster was found dead in his apartment even after teachers and relatives lodged more than a dozen calls to DCFS alleging the mother and her boyfriend were beating, denying food and water to and sexually abusing the boy and his siblings.

Amid all the negative publicity, it was important to Oppenheimer and Harris that their film portrayed a more intimate, nuanced portrayal of foster care than we usually see in the news, one that tells the story from multiple perspectives — the social workers, the kids and the foster parents, all of whom are facing the problem head-on. One of those parents is Earclyne Beavers, who has taken care of over 100 L.A. foster children over the past 25 years.

"We wanted to put a good model of a foster parent on screen because there is a such a need for good foster parents," Oppenheimer said, adding that Beavers always allowed parental visits, which is important because sometimes it's best to reunite foster youth with their birth families — and it can be immensely helpful if foster parents understand and are open to that from the beginning.

Mrs. Beavers and her foster child, Sydney, attend a court hearing to find out if Sydney will be reunified with her family. (Courtesy HBO)

Cassie is Mrs. Beaver's youngest foster child. She has developmental difficulties and has trouble communicating verbally. (Courtesy HBO)

The film also features a foster-youth-turned-social worker named Jessica Chandler, who says to the camera, "this job is hard as hell."

Not surprisingly, it took the filmmakers a long time to get access to the inner-workings of a bureaucratic behemoth like the L.A. County DCFS. A previous director of the agency gave them permission to make a documentary, but when current director Bobby Cagle found out about the agreement, he was skeptical.

"He told us afterwards that a chill went down his spine when he heard that the department had granted some filmmakers unprecedented access. He was terrified of what he might see," Oppenheimer said. "And he was very relieved when he saw the movie...quite moved and emotional. He had been adopted himself, and he said that he wished his parents could have seen the movie, so that they would know the fate that he might have otherwise been spared."

Mary, 18, is coming to terms with her time in foster care. (Courtesy HBO)

Gaining trust among foster youth was equally difficult — many of them struggle with self-esteem around the feeling of not being wanted.

That's the case with Mary, 18, who is currently a student at Cal State Northridge (the filmmakers decided to protect her identity by leaving out her last name). By her account, she lived in 16-18 foster homes after being taken away from her mom, who called her a mistake.

"I've always kind of just wondered what was wrong with me? Why did all these families just give up on me?" she asks in the film. "Why didn't any of my other family members take me in, instead of just watching me get passed around?"

Oppenheimer says if a child has been in that many homes and never finds permanent placement, it's considered "a failure of the system."

"I think this whole movie is about looking at who these kids are and who they can be," said Oppenheimer. "They're not other people's children, they're our children. And we wanted to put a human face on them."

Foster premieres May 7 on HBO.

Tamika Adams and A Martinez contributed to this story.