# Custom font sizes inside section titles

I need to change the size of some text within a section title:

\documentclass{article}
\begin{document}
\section{This text is normal {\Large This text is large}}
\end{document}

This works, however, in some situations, I am using an extra-small font. For example:

\def\Tiny{ \font\Tinyfont = cmr10 at 5pt \relax  \Tinyfont}

When \Tiny is used within the section title, it produces:

Undefined control sequence

• How can I get the \Tiny letters to appear in the section titles
• As the section title text is normally larger than regular text, but \Tiny letters also appear throughout the document, how can I ensure that the Tiny text within the section title is proportionally small (i.e. slightly larger than the \Tiny text within the rest of the document).
• What are you writing!? It's got to be a thesis. It seems like you're popping up every five minutes! :P – qubyte Nov 14 '11 at 13:02
• It is some reference books. Am I asking too many questions? – Village Nov 15 '11 at 1:56
• Not at all! It must be a monster of a project though. – qubyte Nov 15 '11 at 2:15
• To reiterate, I'm not criticising. The whole point of Stack Exchange is the questions, so keep asking. – qubyte Nov 15 '11 at 3:18

You may define a very tiny font just like the standard font commands:

\makeatletter
\newcommand*{\Tiny}{\@setfontsize\Tiny{3pt}{4pt}}
\makeatother

This may be used like \Large or \large. I've used 3pt here, because \tiny is already 5pt at article without size option. So:

\documentclass{article}
\makeatletter
\newcommand*{\Tiny}{\@setfontsize\Tiny{5pt}{6pt}}
\makeatother

\begin{document}
\section{This text is normal {\Tiny This text is very tiny}}
\section{This text is normal {\tiny This text is tiny}}
\end{document}

Would show same font sizes.

BTW: Maybe package relsize would also be interesting for you:

\documentclass{article}
\usepackage{relsize}
\begin{document}
\section{This text is normal {\relsize{-4} This text is very tiny}}
\end{document}

This allows to set sizes not absolute but relative.