Very little, I hope. This thread is about opera!

When I was a kid I remember discovering the MGM musicals, and others, but MGM were the biggest. And Kathryn Grayson, Jeannette McDonald, Nelson Eddy, Howard Keel, Ann Blythe, Jane Powell, and others. I always thought they had the voices for opera, but I seem to recall my mother telling me that they had the looks to make it in the movies and made a lot more money. Does that theory work for the rest of you? Did they have the chops for opera if they so choose? I know there were some crossover folks, between stage and film and opera, but I don't know if any in this group named were part of that group. (John Raitt, Alan Jones, Paul Robeson, I know they were up to the rigors of opera.)

SRS