Piano-Opera:Mutually exclusive?

[sphince]

Greetings!
I was recently hired by my country's national orchestra which is collaborating with a well-known cast to put up Puccini's Tosca.Obviously my job was to substitute the orchestra in the singing rehearsals,which I find pretty neat especially for the paycheck.I was given a month and a half to study the score and I would participate for 2 months.
My question is this:Why the keyboard is out of use in all operas/operettas after mozart?

[iansinclair]

It isn't, really -- but it is usually relegated to being just one of the boys or girls in the band, rather than having the continuo type of position it had (actually very often as a harpsichord) in earlier music.  I doubt that one could come up with a single definitive reason, but as composers always seem to like to push the envelope, and as more and more variety became possible with larger, more varied, and better orchestras, they just kind of naturally wanted to use what was available.  That would be my guess, anyway.

Tosca doesn't illustrate this all that well, although it does -- but listen to what Richard Strauss does with his orchestrations, for example.  Or Berlioz -- try the Requiem (IMHO the single greatest piece of music every written -- but that's just me).

There are many examples of pianos used as orchestral instruments -- try the Shostakovich Fifth Symphony, for example.

[richard black]

Some operas have a part for celesta, a few a part for organ (including Tosca, rather famously), and a very few a part for piano - I've played in the pit in Tobias Picker's 'Thérèse Raquin' (reduced orchestration by the composer - can't remember whether the full-orch version includes a piano) and Thomas Adès' 'Powder Her Face'. And keyboard continuo survived until about the 1830s.