Zen chose his last name because of his fascination with Eastern religions.
He married right after graduating from UCLA in theater arts. He did have a son by this marriage but, with his wife's leave, he kept up his affairs with men. The marriage lasted 50 years.
His first porn experience was seing Sex Garage at which Fred Halsted appeared.
His first film was The Day the Vagina Closed in 1972. One is hard pressed to find information about it. His second film was Tattoo made in 1974. He claimed it was his best ever. Both films he considered 'experimental' because he had very little money to spend on them.
In a Jerry Douglas interview in Manshots, he said that he always would watch his subjects have sex before he would film them so that he would know how to film them without giving them directions. For the 1977 Falconhead film he would observe and then only choose performers who he felt were narcissistic.
The next film, Man Size, was an attempt to make something more commercial but he did not consider it something of his own.
Many of he films were straight films particularly for Vivid.