# Setting the optical size with beamer and fontspec

I am using fontspec to select a font for my beamer presentation. The font I am using has different optical sizes, and fontspec takes full advantage of this. This is great for high resolution print, but for my presentation that is going to be displayed on a low-resolution screen, I would prefer not to use the display size for the title, just the regular optical size everywhere (and maybe even the caption size).

I have the following example:

\documentclass[14pt]{beamer}

\usefonttheme{serif}

\usepackage{polyglossia, fontspec}
\setmainfont[Numbers = {OldStyle, Proportional}]{Minion Pro}

\title{How to set the optical size with beamer and fontspec?}
\author{Ruud v A}

\begin{document}
\begin{frame}
\titlepage
\end{frame}
\end{document}


The trick is to use SizeFeatures together with the OpticalSize option. For example:
\setmainfont[Numbers = {OldStyle, Proportional},

Will use the caption optical size for regular text (with the 14pt option), and the regular optical size for larger text. This works both with LuaLaTeX as well as XeLaTeX.