Ignoring page numbers in backup slides

Question

I am using the beamer document class in latex to make a presentation. I will have a number of back up slides which are there for offline viewing, reference etc. Beamer has a f

Answer 1

Just insert

\renewcommand{\inserttotalframenumber}{\pageref{lastslide}}

after \begin{document}, and place the marker

\label{lastslide}

on your last slide.

Answer 2

Another possibility - which was recently added to beamer - is to use the appendixframenumber template:

\documentclass[t]{beamer}

\setbeamertemplate{footline}{
  \hfill%
  \usebeamercolor[fg]{page number in head/foot}%
  \usebeamerfont{page number in head/foot}%
  \setbeamertemplate{page number in head/foot}[appendixframenumber]%
  \usebeamertemplate*{page number in head/foot}\kern1em\vskip2pt%
}

\begin{document}

    \begin{frame}
        slide in the main part
        \only<2>{blub}
    \end{frame}

    \appendix
    \section*{Backup}

    \begin{frame}
        \frametitle{backup}
        not counting in the total frame number
    \end{frame}

\end{document}

Answer 3

I have defined two commands to do this:

\newcommand{\beginbackup}{
   \newcounter{framenumbervorappendix}
   \setcounter{framenumbervorappendix}{\value{framenumber}}
}
\newcommand{\backupend}{
   \addtocounter{framenumbervorappendix}{-\value{framenumber}}
   \addtocounter{framenumber}{\value{framenumbervorappendix}} 
}

You can then use \beginbackup and \backupend before and after your backup slide to adjust the number of slides.

For my beamer template I also like to add

\setbeamertemplate{footline}{
  \leavevmode%
  \hbox{%
  \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
    \usebeamerfont{author in head/foot}\insertshortauthor~~(\insertshortinstitute)
  \end{beamercolorbox}%
  \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
    \usebeamerfont{title in head/foot}\insertshorttitle
  \end{beamercolorbox}%
  \begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,right]{date in head/foot}%
    \usebeamerfont{date in head/foot}\insertshortdate{}\hspace*{2em}
    \insertframenumber{} \hspace*{2ex} % hier hat's sich geändert
  \end{beamercolorbox}}%
  \vskip0pt%
}

in the definition of the \beginbackup command to hide to total page number in the backup slides, otherwise you'll get something like "24/18".

Using all this, your slides will be numbered like "x/Y" for all slides before the backup, where Y is the total number of slides before the first backup slide, and the backup slides will continue the numbering of the previous slides.