Last week I wrapped up some head shots for a great friend, Liza Malamut. She's working on her DMA at BU, and plays the Sackbut and modern trombone.
Recently she was asked for a headshot to be used for a gig she was offered. This is not an uncommon request. Increasingly, promoters and people hiring musicians want to use a high quality picture of the musicians they are hiring. These will get used on their website, in the printed program, or featured on their promotional materials.
Many people think that headshots are only for actors or singers and instrumentalists just get stuck in the ensemble. Not anymore. A huge part of making it as a successful musician is self promotion. As part of your electronic press kit, you need to have a high quality headshot. If you play multiple primary instruments, you should get a picture that features each instrument. If someone is thinking of hiring you for one part, but you send a picture with another instrument, they may wonder about your skills on the part they're hiring for.
None of us are Dorian Gray. Once we get headshots taken, they will stay the same while we age. We haven't invented the JPEG file that ages on the hard drive in the attic while we retain our youthful looks. So, make sure that you update your headshots every couple of years.