No songwriter casts a deeper shadow than Bob Dylan does, and since the first three volumes of the Bootleg Series came in 1991, his shadow career – now reaching Volume Ten with Another Self Portrait – continues to prove as compelling as the official releases. While the latter are set in stone, the Bootleg Series is more like a basement excavation, digging into the softer darker clays of epochal concerts, wildly alternate versions, and almost willfully lost treasures.

Face Value – heh, who’d have thought to come up with that title for an exhibition of portraits? Yeah, it’s not particularly clever, but there’s something of the contrarian mischief-maker in it all the same, for in the 50 years that Bob Dylan has been making music, giving interviews and being lionised as the son of God, there’s never been much danger of anyone taking him at face value. Or at least there shouldn’t be. And the same could be said of the 12 portraits that make up this exhibition.

Next Monday Bob Dylan releases Another Self Portrait (1969-1971), the tenth volume of his Bootleg Series which casts new light on one of his most maligned records, 1970's Self Portrait. Two days beforehand a selection of his pastel portraits will go on display at the National Portrait Gallery. (Both events, naturally, will be reviewed on theartsdesk.) At 72, popular music's most mercurial character is still throwing curveballs.

Like Orpheus, Bob Dylan is familiar with the underworld. As he gets closer to meeting his maker, the tone of his work has become less baroque, increasingly stripped down and almost naïve in its simplicity. His latest album marks another episode, perhaps the darkest, in a series of sung chronicles, blues-soaked dirges and timeless ballads that draw from the poet’s seemingly unstoppable stream of memories, dreams and reflections.

Bob Dylan once described himself as ''just a song and dance man''. If the phrase was intended to debunk our veneration of him as the voice of a generation and to imply that he's just an old-fashioned entertainer in the great showbiz tradition, devotees have never believed him and have carried on seeking clues to the meaning of life in his work, campaigning for him to win the Nobel Prize for Literature and generally treating his every utterance as if he's the Oracle.

Creative time travel is very much in vogue. For musicians especially, it appears that death is not so much The End as an opportunity to extend the possibilities of the franchise. Early in 2012, American alt-country type Jay Farrar and My Morning Jacket’s Jim James will release New Multitudes, an (excellent) album of new songs based on some of the thousands of unrecorded lyrics left by Woody Guthrie after his death in 1967. It’s just the latest in a line of high-profile collaborations between the living and the dead.

One of Britain’s most esteemed and influential folk artists, Martin Carthy (b 1941) celebrates his 70th birthday on 21 May. The occasion is being marked by the release of a two-disc career overview, Martin Carthy Essential, and next weekend's celebratory concert at the Southbank Centre, London. Much as he obviously appreciates the gesture, there's an unmistakable sense that this self-effacing man would be just as happy spending the night crammed into a howff, eyeballing his audience from a distance of no more than 10 paces.

A near contemporary of the great jazz photographer Herman Leonard, who died last August, Don Hunstein has amassed a formidable collection of images of some of the most indelible names in music, from Miles Davis and John Coltrane to Johnny Cash, Louis Armstrong and Leonard Bernstein. His work with Bob Dylan in the Sixties, when Hunstein was a staff photographer for Columbia Records and Dylan was the visionary folk singer daring to cross the frontier into rock'n'roll, have become an indivisible part of the myth of the Bard of Minnesota.