Adding a frame footnote in beamerposter creates blank page at beginning

Question

If I use a footnote within a column, that footnote is in an inconvenient place (at the bottom of that column), so I solved that by using the [frame] option, which puts the note at the bottom of the frame (the poster).

Here it is with \footnote{a footnote}:

And here it is with \footnote[frame]{a footnote} which looks as I wish it to, but with the extra blank page at the beginning:

This code produces the above documents:

\documentclass[10pt]{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[orientation=portrait, size=custom, width=80, height=40, scale=2]{beamerposter}

\begin{document}
\begin{frame}{}

\begin{block}{\veryHuge A title for my poster}
    \LARGE By askewchan
\end{block}

\begin{columns}[T]
    \column{.5\linewidth}
        some text in a column
    \column{.5\linewidth}
        %some more text in another\footnote{a footnote} column
        some more text in another\footnote[frame]{a footnote} column
\end{columns}
\end{frame}
\end{document}

Any ideas how to avoid this? I'd rather not manually place them if possible.

Answer 1

Your problem is caused by beamerposter (it changes the footnotesize to something larger than normal).

As far as I can see, you just take it to change the page size. If you do this manually, there is no additional page:

\documentclass[10pt]{beamer}
\geometry{papersize={16cm,8cm}}
\begin{document}
\begin{frame}{}
\begin{block}{\Huge A title for my poster}
    \LARGE By askewchan
\end{block}
\begin{columns}[T,onlytextwidth]
    \column{.5\linewidth}
        some text in a column
    \column{.5\linewidth}
        %some more text in another\footnote{a footnote} column
        some more text in another\footnote[frame]{a footnote} column
\end{columns}
\end{frame}
\end{document}

---

If you really really really want to use the beamerposter package, you can make the footnotesize smaller after loading it, e.g.

\documentclass[10pt]{beamer}
\usepackage[orientation=portrait, size=custom, width=80, height=40, scale=2]{beamerposter}
\renewcommand*{\footnotesize}{\fontsize{10}{12}\selectfont}
\begin{document}
\begin{frame}{}
\begin{block}{A title for my poster}
    \LARGE By askewchan
\end{block}
\begin{columns}[T]
    \column{.5\linewidth}
        some text in a column
    \column{.5\linewidth}
        %some more text in another\footnote{a footnote} column
        some more text in another\footnote[frame]{a footnote} column
\end{columns}
\end{frame}
\end{document}