How to set font size for \caption* (but not \caption)

Question

I need to change the font size from \caption* to 10pt.However, using \captionsetup the \caption font size changes as well. How can I solve that?

Answer 1

The following minimal example changes the starred \caption of all floats to be different from that of \caption using etoolbox to patch \caption@@@make:

\documentclass[12pt]{article}
\usepackage[paperheight=4in]{geometry}% http://ctan.org/pkg/geometry
\usepackage{caption}% http://ctan.org/pkg/caption
\usepackage{etoolbox}% http://ctan.org/pkg/etoolbox
\captionsetup{font=small}
\makeatletter
\patchcmd{\caption@@@make}% <cmd>
  {\ifcaption@star}% <search>
    {\ifcaption@star\footnotesize}% <replace>
    {}{}% <success><failure>
\makeatother
\begin{document}
\makeatletter
\begin{figure}\caption{A regular figure caption: \f@size{}pt}\end{figure}
\begin{figure}\caption*{A starred figure caption: \f@size{}pt}\end{figure}
\makeatother
\end{document}

\captionsetup sets the caption font to \small in a 12pt base font, which is equivalent to 10.95pt (for \caption). The patch turns \caption*'s font size into \footnotesize, which is equivalent to 10pt.

geometry was used just for this example to reduce the paper size and may not be needed in your application.