Story highlights Robert De Niro has produced a new documentary about his father, an artist

Robert De Niro Sr. was gay and private about his sexuality

De Niro honors his father broadly, shows off his studio, reads from his diaries

"You can't hide anything," says the actor

Robert De Niro says it was his "responsibility" to make a documentary about his father, artist Robert De Niro Sr., he told Out magazine in an interview.

De Niro's father was a gay man who divorced De Niro's mother when the actor was a child. The elder De Niro is the subject of a new documentary, "Remembering the Artist: Robert De Niro, Sr.," which premieres on HBO June 9. (HBO, like CNN, is a unit of Time Warner.)

In a chat with Out , De Niro says that though he and his father weren't close -- he grew up with his mother -- the senior De Niro had a profound influence on his actor son. De Niro wants to pay tribute in the documentary, partly for the sake of his own children.

"We were not the type of father and son who played baseball together, as you can surmise. But we had a connection," he said. "I wasn't with him a lot, because my mother and he were separated and divorced. ... But my father wasn't a bad father, or absent. He was absent in some ways. He was very loving. He adored me ... as I do my kids."

Robert De Niro at an exhibit of his father's works in 2005. De Niro Sr. is now the subject of a film by his son.

De Niro Sr. was an abstract expressionist painter who was part of an art community that also produced Jackson Pollock, Willem De Kooning and Mark Rothko. As his son notes, when De Niro Sr. had his studio in downtown Manhattan, an area now full of multimillion-dollar apartments, the area was "Siberia." De Niro Sr. died in 1993 and his son has maintained his studio in New York's SoHo neighborhood ever since.

"This space is here, and in 20 years, people won't know what a real space like this will be unless it was in a museum and they recreated it," he said. He had the contents catalogued and has kept them intact.

He says he was only dimly aware of his father's sexuality growing up.

"I was not aware, much, of it. I wish we had spoken about it much more. My mother didn't want to talk about things in general, and you're not interested when you're a certain age," he said.

But both his father and mother gave him the drive to succeed, he added.

"When I was young, I wasn't afraid of being told 'No,'" he said. "I tell my kids, I tell everyone, 'If you don't go, you never know.' I didn't take it as rejection. Certain things are stacked against you. You're coming out of nowhere, starting out — that's part of the excitement of it in a way, too."

In the film, De Niro also reads from his father's diaries, which he's still working through, he said. He may share more of them publicly -- "That's part of his legacy, too," he said -- though he wants to talk to others first.

But the important thing, he said, is getting the whole story out.

"You can't hide anything. That's the whole point -- the truth. That's what people are attracted to," the actor said. "I should have done this 10 years earlier, but I'm glad I did it now."