I know what opera singers go through - I'm married to an opera singer - a dramatic soprano. From her, and our friends (singers and musicians) I understand how the industry functions (incredibly political - worse than acting any day of the week). I know the roles of agents and conductors and directors in getting jobs. I know the plots and characters to hundreds of operas, and I know the roles singers prepare within their fach. I know about spinning the sound and apoggia and all that stuff.
The opera industry is going through a lot of change right now. Companies are looking for young and slender these days. There is also much less of an emphasis on the mystique of a singer and more on the reality of who the person is. As companies continue to try to reinvigorate their audiences (re: get a younger audience into the opera house), opera promotion and presentation will increasingly take its cues from the film and pop music industries.
What does this mean to you? It means Birgit Nillsson is out and Anna Netrebko is in, so plan accordingly. All that big poofy high glamour stuff is becoming passe, which is a good thing in terms of your wardrobe. An opera singer still has to look grand and magical, but in a tangiable, touchable way.
Shooting younger singers are somewhat a specialty of mine. For the younger singer, I think a headshot has to project that youth, perhaps a touch of innocence, and convey a sense of 'feet on the ground.'
Perhaps above all, an opera singer headshot has to get across intelligence. Most of the singers I've met are very very smart. They have to be - it is an incredibly demanding profession.