Do you clap when no one's done anything?

[unicorn]

Am I alone in thinking it's a bit silly when the audience claps as the conductor enters the orchestra pit, or when the curtains rise at the start of a play, musical, or opera? I certainly clap after a piece is played, or after a well-sung aria, and so on. But should just showing up for work merit applause? Occasionally, I will applaud as the curtains are raised, when I see an impressive set. But then I'm applauding the set designer(s)/production crew, whose work is on display, rather than the actors or singers, who haven't started working yet. 

[PeterRS]

I have been to quite a few opera performances in my time and never thought about the tradition of applauding the conductor as he enters the orchestra pit. I think it is partly a mark of respect, in just the same way the audience applaud when a conductor walks to the podium in a symphony concert. I always do it, but I think it is also an ideal way of getting the audience to become perfectly quiet before an opera/concert starts. I actually do not like applause after a particularly well sung aria as this slows down the dramatic action. Nor am I a fan of applauding as the curtain rises just because the scenery is particularly impressive. I think applause should wait till the end of each Act. As @unicorn points out, although the designers' work is finished by then, on opening night all on the production team will appear on stage after the singers and take their own applause.

I love two videos of the Richard Strauss opera Der Rosenkavalier, one conducted by Herbert von Karajan and the other by arguably the finest conductor of the 20th century Carlos Kleiber. Both enter the pit to applause but then do not pause: they start the orchestra virtually at the height of the applause. They get straight into the orchestral prelude which, prior to the curtain rising, depicts two of the main characters making passionate love in bed. It concludes with four quick "upthrusts" on the horns - and what that signifies is perfectly obvious! 

On a side note, a dozen years ago I spent three lovely days in Dresden just to attend a Rosenkavalier performance at the renowned Semper Opera. This was mostly destroyed during the war in the massive air raids on Dresden and it took the city 40 years to reconstuct it. It was where Strauss was Music Director for many years and many of his operas were given their premiere, although not Rosenkavalier. The acoustics are superb. Just next to the hotel where we stayed is the glorious Frauenkirche which was aso partially destroyed during the Dresden bombing. The interior is superb. A burst of colour hits you as you enter.

The exterior of the Semper Opera 

The glorious interior of the Dresden Frauenkirche