How to change fonts in beamer equations

For a long time it was really annoying that the default fonts for the beamer template is just not right. I wanted to have the default fonts back for the equations, that look the same as in articles. Then I found this:

http://tex.stackexchange.com/questions/41572/setting-math-fonts-in-beamer

The solution that was working best for me was:

\usefonttheme[onlymath]{serif}