Last week, I played first horn on the UNLV production of Carmen, by Georges Bizet. I hadn't played in a real opera before (read: anything besides Gilbert and Sullivan or Offenbach) so it was exciting to be a part of. The pit in our school performance hall was big, but the horns were down and behind a railing, which made for some interesting sight lines to the conductor. We were also dangerously close to flying props, as the first flute learned when a barrel flew offstage and hit her in the head... (She got an ice pack and lived to play another solo, don't worry!) The music in an opera is certainly different than most musical theater shows. The orchestration is richer and fuller; there were four horns as opposed to one or two, other sections were filled out with more players, and the woodwinds were not doubling. The challenge of working with singers who are acting, rather than actors who are singing, is different as well. As an instrumentalist, I was obviously not in control of watching the singer and keeping with his/her tempo fluctuations, but an effective pit player needs to be attentive and realize when they will have to look up. No one wants to resolve before the singer does!!
The book for Carmen has a constant rotation of transpositions, so one of the biggest challenges to playing the opera is keeping up with what key you're in. It changes just about every number, and there isn't a lot of downtime through the three hour show. In terms of chop endurance it isn't terribly difficult, but mental endurance is a different story. There were a couple sweet solos I got to play, and of course it's always fun to play the Habañera!