Is the oboe an insrument or a backup instrument?

Answer 1

The Oboe is a main instrumenteven thoughit is often overlooked.The best example is that an oboe tunes up the rest of the orchestrathereforeit is very important.

Also....

The idea of "backup instrument" doesn't really apply for orchestral music.

1. There are oboe concerti, where the oboe is the principal instrument.

2. Composers use combinations of instruments to create "colour" in the sound of the music, and you will often find instruments such as the oboe contributing a major part of that colour, especially in slower, more contemplative and "wistful" passages.