# How to adjust the Beamer default font size more finely?

I can adjust the default font size for a Beamer presentation using any of these options:

\documentclass[pdf,12pt]{beamer} % very small
\documentclass[pdf,14pt]{beamer} % small
\documentclass[pdf,20pt]{beamer} % very large

Values between 14pt and 20pt give the same result as 12pt, but I think the optimal font size lies somewhere between. How can I adjust the font size to something like 18pt?

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beamer allows for a 17pt font size option... –  Werner Jun 12 '13 at 6:47
Oh. I only tried 16pt and 18pt. 17, such an odd number. I'd still like to know how to choose other sizes. –  Tim N Jun 12 '13 at 6:49