A little late to this news, but HBO has a documentary out called Street Gang: How We Got to Sesame Street, about the making of the hugely successful children’s television show. Sesame Street premiered in November, 1969. Karsh met Kermit and the muppet master Jim Henson in March, 1990, just two months before Henson died. Karsh photographed them for his “American Legends” series.
See Karsh’s solo portrait of Jim Henson.